Version: 20 R7 BETA

Collection

The Collection class manages Collection type variables.

A collection is initialized with the New collection or New shared collection commands.

Example

 var $colVar : Collection //creation of collection type 4D variable
 $colVar:=New collection //initialization of the collection and assignment to the 4D variable

Summary


.at( index : Integer ) : any returns the item at position index, allowing for positive and negative integers
.average( {propertyPath : Text } ) : Real returns the arithmetic mean (average) of defined values in the collection instance
.clear() : Collection removes all elements from the collection instance and returns an empty collection
.combine( col2 : Collection {; index : Integer } ) : Collection inserts col2 elements at the end or at the specified index position in the collection instance and returns the edited collection
.concat( value : any { ;...valueN } ) : Collection returns a new collection containing the elements of the original collection with all elements of the value parameter added to the end
.copy() : Collection .copy( option : Integer ) : Collection .copy( option : Integer ; groupWithCol : Collection ) : Collection .copy( option : Integer ; groupWithObj : Object ) : Collection returns a deep copy of the collection instance
.count( { propertyPath : Text } ) : Real returns the number of non-null elements in the collection
.countValues( value : any {; propertyPath : Text } ) : Real returns the number of times value is found in the collection
.distinct( {options : Integer} ) : Collection .distinct( propertyPath : Text {; options : Integer } ) : Collection returns a collection containing only distinct (different) values from the original collection
.equal( collection2 : Collection {; option : Integer } ) : Boolean recursively compares the contents of the collection and collection2 (deep comparison)
.every( { startFrom : Integer ; } formula : 4D.Function { ;...param : any } ) : Boolean .every( { startFrom : Integer ; } methodName : Text { ;...param : any } ) : Boolean returns true if all elements in the collection successfully passed a test implemented in the provided formula object or methodName method
.extract( propertyPath : Text { ; option : Integer } ) : Collection .extract( propertyPath : Text ; targetPath : Text { ;...propertyPathOrTargetPathN : Text } ) : Collection creates and returns a new collection containing propertyPath values extracted from the original collection of objects
.fill( value : any ) : Collection .fill( value : any ; startFrom : Integer { ; end : Integer } ) : Collection fills the collection with the specified value, optionally from startFrom index to end index, and returns the resulting collection
.filter( formula : 4D.Function { ; ...param : any } ) : Collection .filter( methodName : Text { ; ...param : any } ) : Collection returns a new collection containing all elements of the original collection for which the formula or methodName result is true
.find( { startFrom : Integer ; } formula : 4D.Function { ; ...param : any } ) : any .find( { startFrom : Integer ; } methodName : Text { ; ...param : any } ) : any returns the first value in the collection for which formula or methodName result, applied on each element, returns true
.findIndex( { startFrom : Integer ; } formula : 4D.Function { ; ...param : any } ) : Integer .findIndex( { startFrom : Integer ; } methodName : Text { ; ...param : any } ) : Integer returns the index, in the collection, of the first value for which formula or methodName, applied on each element, returns true
.first() : any returns the first element of the collection
.flat( { depth : Integer } ) : Collection creates a new collection with all sub-collection elements concatenated into it recursively up to the specified depth
.flatMap( formula : 4D.Function { ; ...param : any } ) : Collection .flatMap( methodName : Text { ; ...param : any } ) : Collection creates a new collection based upon the result of the call of the formula 4D function or methodName method on each element of the original collection and flattened by a depth of 1
.includes( toSearch : expression { ; startFrom : Integer } ) : Boolean returns True if the toSearch expression is found among collection elements, otherwise False
.indexOf( toSearch : expression { ; startFrom : Integer } ) : Integer searches the toSearch expression among collection elements and returns the index of the first found occurrence, or -1 if it was not found
.indices( queryString : Text { ; ...value : any } ) : Collection returns indexes, in the original collection, of object collection elements that match the queryString search conditions
.insert( index : Integer ; element : any ) : Collection inserts element at the specified index position in the collection instance and returns the edited collection
.join( delimiter : Text { ; option : Integer } ) : Text converts all elements of the collection to strings and concatenates them using the specified delimiter string as separator
.last() : any returns the last element of the collection
.lastIndexOf( toSearch : expression { ; startFrom : Integer } ) : Integer searches the toSearch expression among collection elements and returns the index of the last occurrence
.length : Integer returns the number of elements in the collection
.map( formula : 4D.Function { ; ...param : any } ) : Collection .map( methodName : Text { ; ...param : any } ) : Collection creates a new collection based upon the result of the call of the formula 4D function or methodName method on each element of the original collection
.max( { propertyPath : Text } ) : any returns the element with the highest value in the collection
.min( { propertyPath : Text } ) : any returns the element with the smallest value in the collection
.multiSort() : Collection .multiSort( colsToSort : Collection ) : Collection .multiSort( formula : 4D.Function ; colsToSort : Collection ) : Collection enables you to carry out a multi-level synchronized sort on a set of collections
.orderBy( ) : Collection .orderBy( pathStrings : Text ) : Collection .orderBy( pathObjects : Collection ) : Collection .orderBy( ascOrDesc : Integer ) : Collection returns a new collection containing all elements of the collection in the specified order
.orderByMethod( formula : 4D.Function { ; ...extraParam : expression } ) : Collection .orderByMethod( methodName : Text { ; ...extraParam : expression } ) : Collection returns a new collection containing all elements of the collection in the order defined through the formula 4D function or methodName method
.pop() : any removes the last element from the collection and returns it as the function result
.push( element : any { ;...elementN } ) : Collection appends one or more element(s) to the end of the collection instance and returns the edited collection
.query( queryString : Text ) : Collection .query( queryString : Text ; ...value : any ) : Collection .query( queryString : Text ; querySettings : Object ) : Collection returns all elements of a collection of objects that match the search conditions
.reduce( formula : 4D.Function { ; initValue : any { ; ...param : expression }} ) : any .reduce( methodName : Text { ; initValue : any { ; ...param : expression }} ) : any applies the formula or methodName callback against an accumulator and each element in the collection (from left to right) to reduce it to a single value
.reduceRight( formula : 4D.Function { ; initValue : any { ; ...param : expression }} ) : any .reduceRight( methodName : Text { ; initValue : any { ; ...param : expression }} ) : any applies the formula or methodName callback against an accumulator and each element in the collection (from right to left) to reduce it to a single value
.remove( index : Integer { ; howMany : Integer } ) : Collection removes one or more element(s) from the specified index position in the collection and returns the edited collection
.resize( size : Integer { ; defaultValue : any } ) : Collection sets the collection length to the specified new size and returns the resized collection
.reverse( ) : Collection returns a deep copy of the collection with all its elements in reverse order
.shift() : any removes the first element of the collection and returns it as the function result
.slice( startFrom : Integer { ; end : Integer } ) : Collection returns a portion of a collection into a new collection
.some( { startFrom : Integer ; } formula : 4D.Function { ; ...param : any } ) : Boolean .some( { startFrom : Integer ; } methodName : Text { ; ...param : any } ) : Boolean returns true if at least one element in the collection successfully passed a test implemented in the provided formula or methodName code
.sort() : Collection .sort( formula : 4D.Function { ; ...extraParam : any } ) : Collection .sort( methodName : Text { ; ...extraParam : any } ) : Collection sorts the elements of the original collection and also returns the sorted collection
.sum( { propertyPath : Text } ) : Real returns the sum for all values in the collection instance
.unshift( value : any { ;...valueN : any } ) : Collection inserts the given value(s) at the beginning of the collection

.at()

History

Release	Changes
20	Added

.at( index : Integer ) : any

Parameter	Type		Description
index	Integer	->	Index of element to return
Result	any	<-	The element at that index

Description

The .at() function returns the item at position index, allowing for positive and negative integers.

Negative integers count back from the last item in the collection.

The function returns Undefined if index is beyond collection limits.

Example

var $col : Collection
$col:=New collection(10; 20; 30; 40; 50)
$element:=$col.at(0) // 10
$element:=$col.at(1) // 20
$element:=$col.at(-1) // 50
$element:=$col.at(-2) // 40
$element:=$col.at(10) // undefined

.average()

History

Release	Changes
v16 R6	Added

.average( {propertyPath : Text } ) : Real

Parameter	Type		Description
propertyPath	Text	->	Object property path to be used for calculation
Result	Real, Undefined	<-	Arithmetic mean (average) of collection values

Description

The .average() function returns the arithmetic mean (average) of defined values in the collection instance.

Only numerical elements are taken into account for the calculation (other element types are ignored).

If the collection contains objects, pass the propertyPath parameter to indicate the object property to take into account.

.average() returns undefined if:

the collection is empty,
the collection does not contain numerical elements,
propertyPath is not found in the collection.

Example 1

 var $col : Collection
 $col:=New collection(10;20;"Monday";True;6)
 $vAvg:=$col.average() //12

Example 2

 var $col : Collection
 $col:=New collection
 $col.push(New object("name";"Smith";"salary";10000))
 $col.push(New object("name";"Wesson";"salary";50000))
 $col.push(New object("name";"Gross";"salary";10500))
 $vAvg:=$col.average("salary") //23500

.clear()

History

Release	Changes
v16 R6	Added

.clear() : Collection

Parameter	Type		Description
Result	Collection	<-	Original collection with all elements removed

Description

The .clear() function removes all elements from the collection instance and returns an empty collection.

Example

var $col : Collection
$col:=New collection(1;2;5)
$col.clear()
$vSize:=$col.length //$vSize=0

.combine()

History

Release	Changes
v16 R6	Added

.combine( col2 : Collection {; index : Integer } ) : Collection

Parameter	Type		Description
col2	Collection	->	Collection to combine
index	Integer	->	Position to which insert elements to combine in collection (default=length+1)
Result	Collection	<-	Original collection containing combined element(s)

Description

The .combine() function inserts col2 elements at the end or at the specified index position in the collection instance and returns the edited collection. Unlike the .insert() function, .combine() adds each value of col2 in the original collection, and not as a single collection element.

By default, col2 elements are added at the end of the orginal collection. You can pass in index the position where you want the col2 elements to be inserted in the collection.

If index > the length of the collection, the actual starting index will be set to the length of the collection.
If index < 0, it is recalculated as index:=index+length (it is considered as the offset from the end of the collection).
If the calculated value is negative, index is set to 0.

Example

var $c; $fruits : Collection
$c:=New collection(1;2;3;4;5;6)
$fruits:=New collection("Orange";"Banana";"Apple";"Grape")
$c.combine($fruits;3) //[1,2,3,"Orange","Banana","Apple","Grape",4,5,6]

.concat()

History

Release	Changes
v16 R6	Added

.concat( value : any { ;...valueN } ) : Collection

Parameter	Type		Description
value	Number, Text, Object, Collection, Date, Time, Boolean, Picture	->	Value(s) to concatenate. If value is a collection, all collection elements are added to the original collection
Result	Collection	<-	New collection with value(s) added to the original collection

Description

The .concat() function returns a new collection containing the elements of the original collection with all elements of the value parameter added to the end.

If value is a collection, all its elements are added as new elements at the end of the original collection. If value is not a collection, it is added itself as a new element.

Example

var $c : Collection
$c:=New collection(1;2;3;4;5)
$fruits:=New collection("Orange";"Banana";"Apple";"Grape")
$fruits.push(New object("Intruder";"Tomato"))
$c2:=$c.concat($fruits) //[1,2,3,4,5,"Orange","Banana","Apple","Grape",{"Intruder":"Tomato"}]
$c2:=$c.concat(6;7;8) //[1,2,3,4,5,6,7,8]

.copy()

History

Release	Changes
18 R3	New ck shared option. New groupWith parameters
v16 R6	Added

.copy() : Collection
.copy( option : Integer ) : Collection
.copy( option : Integer ; groupWithCol : Collection ) : Collection
.copy( option : Integer ; groupWithObj : Object ) : Collection

Parameter	Type		Description
option	Integer	->	`ck resolve pointers`: resolve pointers before copying, `ck shared`: return a shared collection
groupWithCol	Collection	->	Shared collection to be grouped with the resulting collection
groupWithObj	Object	->	Shared object to be grouped with the resulting collection
Result	Collection	<-	Deep copy of the original collection

Description

The .copy() function returns a deep copy of the collection instance.Deep copy means that objects or collections within the original collection are duplicated and do not share any reference with the returned collection.

If passed, the option parameter can contain one of the following constants (or both):

option	Description
`ck resolve pointers`	If the original collection contains pointer type values, by default the copy also contains the pointers. However, you can resolve pointers when copying by passing the `ck resolve pointers` constant. In this case, each pointer present in the collection is evaluated when copying and its dereferenced value is used.
`ck shared`	By default, `copy()` returns a regular (not shared) collection, even if the command is applied to a shared collection. Pass the `ck shared` constant to create a shared collection. In this case, you can use the groupWith parameter to associate the shared collection with another collection or object (see below).

The groupWithCol or groupWithObj parameters allow you to designate a collection or an object with which the resulting collection should be associated.

note

Datastore, dataclass, and entity objects are not copiable. If .copy() is called with them, Null values are returned.

Example 1

We want to copy the $lastnames regular (non shared) collection into the $sharedObject shared object. To do this, we must create a shared copy of the collection ($sharedLastnames).

var $sharedObject : Object
var $lastnames;$sharedLastnames : Collection
var $text : Text

$sharedObject:=New shared object

$text:=Document to text(Get 4D folder(Current resources folder)+"lastnames.txt")
$lastnames:=JSON Parse($text) //$lastnames is a regular collection

$sharedLastnames:=$lastnames.copy(ck shared) //$sharedLastnames is a shared collection

//Now we can put $sharedLastnames into $sharedObject
Use($sharedObject)
    $sharedObject.lastnames:=$sharedLastnames
End use

Example 2

We want to combine $sharedColl1 and $sharedColl2. Since they belong to different shared groups, a direct combination would result in an error. Therefore, we must make a shared copy of $sharedColl1 and designate $sharedColl2 as a shared group for the copy.

var $sharedColl1;$sharedColl2;$copyColl : Collection

$sharedColl1:=New shared collection(New shared object("lastname";"Smith"))
$sharedColl2:=New shared collection(New shared object("lastname";"Brown"))

//$copyColl belongs to the same shared group as $sharedColl2
 $copyColl:=$sharedColl1.copy(ck shared;$sharedColl2)
 Use($sharedColl2)
    $sharedColl2.combine($copyColl)
 End use

Example 3

We have a regular collection ($lastnames) and we want to put it in the Storage of the application. To do this, we must create a shared copy beforehand ($sharedLastnames).

var $lastnames;$sharedLastnames : Collection
var $text : Text

$text:=Document to text(Get 4D folder(Current resources folder)+"lastnames.txt")
$lastnames:=JSON Parse($text) //$lastnames is a regular collection

$sharedLastnames:=$lastnames.copy(ck shared) // shared copy

Use(Storage)
    Storage.lastnames:=$sharedLastnames
End use

Example 4

This example illustrates the use of the ck resolve pointers option:

 var $col : Collection
 var $p : Pointer
 $p:=->$what

 $col:=New collection
 $col.push(New object("alpha";"Hello";"num";1))
 $col.push(New object("beta";"You";"what";$p))

 $col2:=$col.copy()
 $col2[1].beta:="World!"
 ALERT($col[0].alpha+" "+$col2[1].beta) //displays "Hello World!"

 $what:="You!"
 $col3:=$col2.copy(ck resolve pointers)
 ALERT($col3[0].alpha+" "+$col3[1].what) //displays "Hello You!"

.count()

History

Release	Changes
v16 R6	Added

.count( { propertyPath : Text } ) : Real

Parameter	Type		Description
propertyPath	Text	->	Object property path to be used for calculation
Result	Real	<-	Number of elements in the collection

Description

The .count() function returns the number of non-null elements in the collection.

If the collection contains objects, you can pass the propertyPath parameter. In this case, only elements that contain the propertyPath are taken into account.

Example

 var $col : Collection
 var $count1;$count2 : Real
 $col:=New collection(20;30;Null;40)
 $col.push(New object("name";"Smith";"salary";10000))
 $col.push(New object("name";"Wesson";"salary";50000))
 $col.push(New object("name";"Gross";"salary";10500))
 $col.push(New object("lastName";"Henry";"salary";12000))
 $count1:=$col.count() //$count1=7
 $count2:=$col.count("name") //$count2=3

.countValues()

History

Release	Changes
v16 R6	Added

.countValues( value : any {; propertyPath : Text } ) : Real

Parameter	Type		Description
value	Text, Number, Boolean, Date, Object, Collection	->	Value to count
propertyPath	Text	->	Object property path to be used for calculation
Result	Real	<-	Number of occurrences of the value

Description

The .countValues() function returns the number of times value is found in the collection.

You can pass in value:

a scalar value (text, number, boolean, date),
an object or a collection reference.

For an element to be found, the type of value must be equivalent to the type of the element; the method uses the equality operator.

The optional propertyPath parameter allows you to count values inside a collection of objects: pass in propertyPath the path of the property whose values you want to count.

Example 1

 var $col : Collection
 var $vCount : Integer
 $col:=New collection(1;2;5;5;5;3;6;4)
 $vCount:=$col.countValues(5) // $vCount=3

Example 2

 var $col : Collection
 var $vCount : Integer
 $col:=New collection
 $col.push(New object("name";"Smith";"age";5))
 $col.push(New object("name";"Wesson";"age";2))
 $col.push(New object("name";"Jones";"age";3))
 $col.push(New object("name";"Henry";"age";4))
 $col.push(New object("name";"Gross";"age";5))
 $vCount:=$col.countValues(5;"age") //$vCount=2

Example 3

 var $numbers; $letters : Collection
 var $vCount : Integer

 $letters:=New collection("a";"b";"c")
 $numbers:=New collection(1;2;$letters;3;4;5)

 $vCount:=$numbers.countValues($letters) //$vCount=1

.distinct()

History

Release	Changes
20	Support of `ck count values`
v16 R6	Added

.distinct( {options : Integer} ) : Collection
.distinct( propertyPath : Text {; options : Integer } ) : Collection

Parameter	Type		Description
propertyPath	Text	->	Path of attribute whose distinct values you want to get
options	Integer	->	`ck diacritical`, `ck count values`
Result	Collection	<-	New collection with only distinct values

Description

The .distinct() function returns a collection containing only distinct (different) values from the original collection.

The returned collection is automatically sorted. Null values are not returned.

If the collection contains objects, you can pass the propertyPath parameter to indicate the object property whose distinct values you want to get.

In the options parameter, you can pass one or a combination of the following constants:

Constant	Value	Comment
`ck diacritical`	8	Evaluation is case sensitive and differentiates accented characters. By default if omitted, a non-diacritical evaluation is performed
`ck count values`	32	Return the count of elements for every distinct value. When this option is passed, `.distinct()` returns a collection of objects containing a pair of `{"value":value;"count":count}` attributes.

Examples

 var $c; $c2; $c3 : Collection
 $c:=New collection
 $c.push("a";"b";"c";"A";"B";"c";"b";"b")
 $c.push(New object("size";1))
 $c.push(New object("size";3))
 $c.push(New object("size";1))
 $c2:=$c.distinct() //$c2=["a","b","c",{"size":1},{"size":3},{"size":1}]
 $c2:=$c.distinct(ck diacritical) //$c2=["a","A","b","B","c",{"size":1},{"size":3},{"size":1}]
 $c2:=$c.distinct("size") //$c2=[1,3]
 $c3:=$c.distinct("size";ck count values) //$c3=[{value:1,count:2},{value:3,count:1}]

.equal()

History

Release	Changes
v16 R6	Added

.equal( collection2 : Collection {; option : Integer } ) : Boolean

Parameter	Type		Description
collection2	Collection	->	Collection to compare
option	Integer	->	`ck diacritical`: diacritical evaluation ("A" # "a" for example)
Result	Boolean	<-	True if collections are identical, false otherwise

Description

The .equal() function recursively compares the contents of the collection and collection2 (deep comparison)and returns true if they are identical.

Notes

The .equal() function only checks equality for string, boolean, number, and null type elements in the collections. It does not check equality for native objects.
Elements with null values are not equal to Undefined elements.

By default, a non-diacritical evaluation is performed. If you want the evaluation to be case sensitive or to differentiate accented characters, pass the ck diacritical constant in the option parameter.

tip

A recursive comparison of collections can be time-consuming if the collection is large and deep. If you only want to compare two collection references, you may consider using the = comparison operator for collection references.

Example

 var $c; $c2 : Collection
 var $b : Boolean

 $c:=New collection(New object("a";1;"b";"orange");2;3)
 $c2:=New collection(New object("a";1;"b";"orange");2;3;4)
 $b:=$c.equal($c2) // false

 $c:=New collection(New object("1";"a";"b";"orange");2;3)
 $c2:=New collection(New object("a";1;"b";"orange");2;3)
 $b:=$c.equal($c2) // false

 $c:=New collection(New object("a";1;"b";"orange");2;3)
 $c2:=New collection(New object("a";1;"b";"ORange");2;3)
 $b:=$c.equal($c2) // true

 $c:=New collection(New object("a";1;"b";"orange");2;3)
 $c2:=New collection(New object("a";1;"b";"ORange");2;3)
 $b:=$c.equal($c2;ck diacritical) //false

.every()

History

Release	Changes
19 R6	Support of formula
v16 R6	Added

.every( { startFrom : Integer ; } formula : 4D.Function { ;...param : any } ) : Boolean
.every( { startFrom : Integer ; } methodName : Text { ;...param : any } ) : Boolean

Parameter	Type		Description
startFrom	Integer	->	Index to start the test at
formula	4D.Function	->	Formula object
methodName	Text	->	Name of a method
param	any	->	Parameter(s) to pass to formula or methodName
Result	Boolean	<-	True if all elements successfully passed the test

Description

The .every() function returns true if all elements in the collection successfully passed a test implemented in the provided formula object or methodName method.

You designate the callback to be executed to evaluate collection elements using either:

formula (recommended syntax), a Formula object that can encapsulate any executable expressions, including functions and project methods;
or methodName, the name of a project method (text).

The callback is called with the parameter(s) passed in param (optional). The callback can perform any test, with or without the parameter(s) and must return true for every element fulfilling the test. It receives an Object in first parameter ($1).

The callback receives the following parameters:

in $1.value: element value to be evaluated
in $2: param
in $N...: paramN...

It can set the following parameter(s):

(mandatory if you used a method) $1.result (Boolean): true if the element value evaluation is successful, false otherwise.
$1.stop (Boolean, optional): true to stop the method callback. The returned value is the last calculated.

In all cases, at the point when the .every() function encounters the first collection element evaluated to false, it stops calling the callback and returns false.

By default, .every() tests the whole collection. Optionally, you can pass in startFrom the index of the element from which to start the test.

If startFrom >= the collection's length, false is returned, which means the collection is not tested.
If startFrom < 0, it is considered as the offset from the end of the collection ( startFrom:=startFrom+length).
If startFrom = 0, the whole collection is searched (default).

Example 1

var $c : Collection  
var $b : Boolean
var $f : 4D.Function

$f:=Formula($1.value>0)
$c:=New collection
$c.push(5;3;1;4;6;2)
$b:=$c.every($f) //returns true
$c.push(-1)
$b:=$c.every($f) //returns false

Example 2

This example tests that all elements of a collection are of the real type:

var $c : Collection
var $b : Boolean
var $f : 4D.Function

$f:=Formula(Value type($1.value)=$2
$c:=New collection
$c.push(5;3;1;4;6;2)
$b:=$c.every($f;Is real) //$b=true
$c:=$c.push(New object("name";"Cleveland";"zc";35049))
$c:=$c.push(New object("name";"Blountsville";"zc";35031))
$b:=$c.every($f;Is real) //$b=false

.extract()

History

Release	Changes
v16 R6	Added

.extract( propertyPath : Text { ; option : Integer } ) : Collection
.extract( propertyPath : Text ; targetPath : Text { ;...propertyPathOrTargetPathN : Text } ) : Collection

Parameter	Type		Description
propertyPath	Text	->	Object property path whose values must be extracted to the new collection
targetpath	Text	->	Target property path or property name
option	Integer	->	`ck keep null`: include null properties in the returned collection (ignored by default). Parameter ignored if targetPath passed.
Result	Collection	<-	New collection containing extracted values

Description

The .extract() function creates and returns a new collection containing propertyPath values extracted from the original collection of objects.

The contents of the returned collection depends on the targetPath parameter:

If the targetPath parameter is omitted, .extract() populates the new collection with the propertyPath values of the original collection.

By default, elements for which propertyPath is null or undefined are ignored in the resulting collection. You can pass the ck keep null constant in the option parameter to include these values as null elements in the returned collection.
If one or more targetPath parameter(s) are passed (corresponding to one or more propertyPath parameter(s)), .extract() populates the new collection with the propertyPath properties and each element of the new collection is an object with targetPath properties filled with the matching propertyPath properties. Null values are kept (option parameter is ignored with this syntax).

Example 1

var $c : Collection
$c:=New collection
$c.push(New object("name";"Cleveland"))
$c.push(New object("zip";5321))
$c.push(New object("name";"Blountsville"))
$c.push(42)
$c2:=$c.extract("name") // $c2=[Cleveland,Blountsville]
$c2:=$c.extract("name";ck keep null) //$c2=[Cleveland,null,Blountsville,null]

Example 2

var $c : Collection
$c:=New collection
$c.push(New object("zc";35060))
$c.push(New object("name";Null;"zc";35049))
$c.push(New object("name";"Cleveland";"zc";35049))
$c.push(New object("name";"Blountsville";"zc";35031))
$c.push(New object("name";"Adger";"zc";35006))
$c.push(New object("name";"Clanton";"zc";35046))
$c.push(New object("name";"Clanton";"zc";35045))
$c2:=$c.extract("name";"City") //$c2=[{City:null},{City:Cleveland},{City:Blountsville},{City:Adger},{City:Clanton},{City:Clanton}]
$c2:=$c.extract("name";"City";"zc";"Zip") //$c2=[{Zip:35060},{City:null,Zip:35049},{City:Cleveland,Zip:35049},{City:Blountsville,Zip:35031},{City:Adger,Zip:35006},{City:Clanton,Zip:35046},{City:Clanton,Zip:35045}]

.fill()

History

Release	Changes
v16 R6	Added

.fill( value : any ) : Collection
.fill( value : any ; startFrom : Integer { ; end : Integer } ) : Collection

Parameter	Type		Description
value	number, Text, Collection, Object, Date, Boolean	->	Filling value
startFrom	Integer	->	Start index (included)
end	Integer	->	End index (not included)
Result	collection	<-	Original collection with filled values

Description

The .fill() function fills the collection with the specified value, optionally from startFrom index to end index, and returns the resulting collection.

If the startFrom parameter is omitted, value is set to all collection elements (startFrom=0).
If the startFrom parameter is passed and end omitted, value is set to collection elements starting at startFrom to the last element of the collection (end=length).
If both the startFrom parameter and end are passed, value is set to collection elements starting at startFrom to the element end.

In case of inconsistency, the following rules apply:

If startFrom < 0, it is recalculated as startFrom:=startFrom+length (it is considered as the offset from the end of the collection). If the calculated value is negative, startFrom is set to 0.
If end < 0 , it is recalculated as end:=end+length.
If end < startFrom (passed or calculated values), the method does nothing.

Example

 var $c : Collection
 $c:=New collection(1;2;3;"Lemon";Null;"";4;5)
 $c.fill("2") // $c:=[2,2,2,2,2,2,2,2]
 $c.fill("Hello";5) // $c=[2,2,2,2,2,Hello,Hello,Hello]
 $c.fill(0;1;5) // $c=[2,0,0,0,0,Hello,Hello,Hello]
 $c.fill("world";1;-5) //-5+8=3 -> $c=[2,"world","world",0,0,Hello,Hello,Hello]

.filter()

History

Release	Changes
19 R6	Support of formula
v16 R6	Added

.filter( formula : 4D.Function { ; ...param : any } ) : Collection
.filter( methodName : Text { ; ...param : any } ) : Collection

Parameter	Type		Description
formula	4D.Function	->	Formula object
methodName	Text	->	Name of a method
param	any	->	Parameter(s) to pass to formula or methodName
Result	Collection	<-	New collection containing filtered elements (shallow copy)

Description

The .filter() function returns a new collection containing all elements of the original collection for which the formula or methodName result is true. This function returns a shallow copy, which means that objects or collections in both collections share the same reference. If the original collection is a shared collection, the returned collection is also a shared collection.

You designate the callback to be executed to filter collection elements using either:

formula (recommended syntax), a Formula object that can encapsulate any executable expressions, including functions and project methods;
or methodName, the name of a project method (text).

The callback is called with the parameter(s) passed in param (optional) and an object in first parameter ($1). The callback can perform any test, with or without the parameter(s) and must return true for each element fulfilling the condition and thus, to push to the new collection.

The callback receives the following parameters:

in $1.value: element value to be evaluated
in $2: param
in $N...: paramN...

It can set the following parameter(s):

$1.result (Boolean): true if the element value matches the filter condition and must be kept, false otherwise.
$1.stop (Boolean, optional): true to stop the method callback. The returned value is the last calculated.

note

When using methodName as callback, and if the method does not return any value, .filter() will look at the property $1.result that you must set to true for each element fulfilling the condition.

Example 1

You want to get the collection of text elements whose length is smaller than 6:

var $col;$colNew : Collection
$col:=New collection("hello";"world";"red horse";66;"tim";"san jose";"miami")
$colNew:=$col.filter(Formula((Value type($1.value)=Is text) && (Length($1.value)<$2)); 6)
  //$colNew=["hello","world","tim","miami"]

Example 2

You want to filter elements according to their value type:

 var $c;$c2;$c3 : Collection
 var $f : 4D.Function

 $f:=Formula(OB Get type($1;"value")=$2)
 $c:=New collection(5;3;1;4;6;2)
 $c.push(New object("name";"Cleveland";"zc";35049))
 $c.push(New object("name";"Blountsville";"zc";35031))
 $c2:=$c.filter($f;Is real) // $c2=[5,3,1,4,6,2]
 $c3:=$c.filter($f;Is object)
  // $c3=[{name:Cleveland,zc:35049},{name:Blountsville,zc:35031}]

.find()

History

Release	Changes
19 R6	Support of formula
v16 R6	Added

.find( { startFrom : Integer ; } formula : 4D.Function { ; ...param : any } ) : any
.find( { startFrom : Integer ; } methodName : Text { ; ...param : any } ) : any

Parameter	Type		Description
startFrom	Integer	->	Index to start the search at
formula	4D.Function	->	Formula object
methodName	Text	->	Name of a method
param	any	->	Parameter(s) to pass to formula or methodName
Result	any	<-	First value found, or Undefined if not found

Description

The .find() function returns the first value in the collection for which formula or methodName result, applied on each element, returns true.

You designate the callback to be executed to evaluate collection elements using either:

formula (recommended syntax), a Formula object that can encapsulate any executable expressions, including functions and project methods;
or methodName, the name of a project method (text).

The callback is called with the parameter(s) passed in param (optional). The callback can perform any test, with or without the parameter(s) and must return true for the first element fulfilling the condition. It receives an Object in first parameter ($1).

The callback receives the following parameters:

in $1.value: element value to be evaluated
in $2: param
in $N...: paramN...

It can set the following parameter(s):

(mandatory if you used a method) $1.result (Boolean): true if the element value matches the search condition, false otherwise.
$1.stop (Boolean, optional): true to stop the method callback. The returned value is the last calculated.

By default, .find() searches in the whole collection. Optionally, you can pass in startFrom the index of element from which to start the search.

If startFrom >= the collection's length, -1 is returned, which means the collection is not searched.
If startFrom < 0, it is considered as the offset from the end of the collection (startFrom:=startFrom+length). Note: Even if startFrom is negative, the collection is still searched from left to right.
If startFrom = 0, the whole collection is searched (default).

Example 1

You want to get the first text element with a length smaller than 5:

var $col : Collection
$col:=New collection("hello";"world";4;"red horse";"tim";"san jose")
$value:=$col.find(Formula((Value type($1.value)=Is text) && (Length($1.value)<$2)); 5) //$value="tim"

Example 2

You want to find a city name within a collection:

var $c : Collection
var $c2 : Object
$c:=New collection
$c.push(New object("name"; "Cleveland"; "zc"; 35049))
$c.push(New object("name"; "Blountsville"; "zc"; 35031))
$c.push(New object("name"; "Adger"; "zc"; 35006))
$c.push(New object("name"; "Clanton"; "zc"; 35046))
$c.push(New object("name"; "Clanton"; "zc"; 35045))

$c2:=$c.find(Formula($1.value.name=$2); "Clanton")  //$c2={name:Clanton,zc:35046}

.findIndex()

History

Release	Changes
19 R6	Support of formula
v16 R6	Added

.findIndex( { startFrom : Integer ; } formula : 4D.Function { ; ...param : any } ) : Integer
.findIndex( { startFrom : Integer ; } methodName : Text { ; ...param : any } ) : Integer

Parameter	Type		Description
startFrom	Integer	->	Index to start the search at
formula	4D.Function	->	Formula object
methodName	Text	->	Name of a method
param	any	->	Parameter(s) to pass to formula or methodName
Result	Integer	<-	Index of first value found, or -1 if not found

Description

The .findIndex() function returns the index, in the collection, of the first value for which formula or methodName, applied on each element, returns true.

You designate the callback to be executed to evaluate collection elements using either:

formula (recommended syntax), a Formula object that can encapsulate any executable expressions, including functions and project methods;
methodName, the name of a project method (text).

The callback receives the following parameters:

in $1.value: element value to be evaluated
in $2: param
in $N...: paramN...

It can set the following parameter(s):

(mandatory if you used a method) $1.result (Boolean): true if the element value matches the search condition, false otherwise.
$1.stop (Boolean, optional): true to stop the method callback. The returned value is the last calculated.

By default, .findIndex() searches in the whole collection. Optionally, you can pass in startFrom the index of element from which to start the search.

If startFrom >= the collection's length, -1 is returned, which means the collection is not searched.
If startFrom < 0, it is considered as the offset from the end of the collection (startFrom:=startFrom+length). Note: Even if startFrom is negative, the collection is still searched from left to right.
If startFrom = 0, the whole collection is searched (default).

Example

You want to find the position of the first city name within a collection:

var $c : Collection
var $val2;$val3 : Integer
$c:=New collection
$c.push(New object("name";"Cleveland";"zc";35049))
$c.push(New object("name";"Blountsville";"zc";35031))
$c.push(New object("name";"Adger";"zc";35006))
$c.push(New object("name";"Clanton";"zc";35046))
$c.push(New object("name";"Clanton";"zc";35045))
$val2:=$c.findIndex(Formula($1.value.name=$2);"Clanton") // $val2=3
$val3:=$c.findIndex($val2+1;Formula($1.value.name=$2);"Clanton") //$val3=4

.first()

History

Release	Changes
20	Added

.first() : any

Parameter	Type		Description
Result	any	<-	First element of collection

Description

The .first() function returns the first element of the collection.

The function returns Undefined if the collection is empty.

Example

var $col; $emptyCol : Collection
var $first : Variant
$col:=New collection(10; 20; 30; "hello"; 50)
$first:=$col.first() // 10

$emptyCol:=New collection() //empty
// $first:=$emptyCol[0] //would return error
$first:=$emptyCol.first() // returns Undefined

.flat()

History

Release	Changes
20	Added

.flat( { depth : Integer } ) : Collection

Parameter	Type		Description
depth	Integer	->	How deep a nested collection structure should be flattened. Default=1
Result	Collection	<-	Flattened collection

Description

The .flat() function creates a new collection with all sub-collection elements concatenated into it recursively up to the specified depth.

By default, if the depth parameter is omitted, only the first level of the nested collection structure will be flattened.

Example

$col:=New collection(1; 2; New collection(3; 4))
$col.flat()
// [1, 2, 3, 4]

$col:=New collection(1; 2; New collection(3; 4; New collection(5; 6)))
$col.flat()
// [1, 2, 3, 4, [5, 6]]

$col:=New collection(1; 2; New collection(3; 4; New collection(5; 6)))
$col.flat(2)
// [1, 2, 3, 4, 5, 6]

$col:=New collection(1; 2; New collection(3; 4; 5; 6; New collection(7; 8; New collection(9; 10))))
$col.flat(MAXLONG)
// [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

.flatMap()

History

Release	Changes
20	Added

.flatMap( formula : 4D.Function { ; ...param : any } ) : Collection
.flatMap( methodName : Text { ; ...param : any } ) : Collection

Parameter	Type		Description
formula	4D.Function	->	Formula object
methodName	Text	->	Name of a method
param	any	->	Parameter(s) to pass to formula or methodName
Result	Collection	<-	Collection of transformed values and flattened by a depth of 1

Description

The .flatMap() function creates a new collection based upon the result of the call of the formula 4D function or methodName method on each element of the original collection and flattened by a depth of 1. Optionally, you can pass parameters to formula or methodName using the param parameter(s).

This function is identical to a map() call followed by a flat() call of depth 1.

You designate the callback to be executed to evaluate collection elements using either:

formula (recommended syntax), a Formula object that can encapsulate any executable expressions, including functions and project methods;
or methodName, the name of a project method (text).

The callback is called with the parameter(s) passed in param (optional). The callback can perform any operation, with or without the parameter(s) and must return new transformed value to add to the resulting collection. It receives an Object in first parameter ($1).

The callback receives the following parameters:

in $1.value: element value to be evaluated
in $2: param
in $N...: paramN...

It can set the following parameter(s):

(mandatory if you used a method) $1.result (any type): new transformed value to add to the resulting collection
$1.stop (Boolean, optional): true to stop the method callback. The returned value is the last calculated.

Example 1

var $col ; $result : Collection
$col:=New collection(1; 2; 3; 4)

$result:=$col.map(Formula(New collection($1.value*2))
 // [[2],[4],[6],[8]]

$result:=$col.flatMap(Formula(New collection($1.value*2))
// [2,4,6,8]

Example 2

var $col; $result : Collection
$col:=New collection("Hello how"; ""; "are you ?")

$result:=$col.map(Formula(Split string($1.value; " ")))
// [["Hello", "how"], [], ["are", "you", "?"]]

$result:=$col.flatMap(Formula(Split string($1.value; " ")))
// ["Hello", "how", "are", "you", "?"]

Example 3

You want to compute the percentage of each value in the collection to the total:

var $c; $c2 : Collection
var $f : 4D.Function
$c:=New collection(1; 4; 9; 10; 20)
$f:=Formula(New collection($1.value;Round(($1.value/$2)*100; 2)))
$c2:=$c.flatMap($f; $c.sum())
  //$c2=[1, 2.27, 4, 9.09,9, 20.45,10, 22.73, 20, 45.45]

.includes()

History

Release	Changes
20	Added

.includes( toSearch : expression { ; startFrom : Integer } ) : Boolean

Parameter	Type		Description
toSearch	expression	->	Expression to search in the collection
startFrom	Integer	->	Index to start the search at
Result	Boolean	<-	True if toSearch is found in the collection

Description

The .includes() function returns True if the toSearch expression is found among collection elements, otherwise False.

In toSearch, pass the expression to find in the collection. You can pass:

a scalar value (text, number, boolean, date),
the null value,
an object or a collection reference.

toSearch must match exactly the element to find (the same rules as for the equality operator of the data type are applied).

Optionally, you can pass the index of collection from which to start the search in startFrom.

If startFrom >= collection's length, False is returned, which means the collection is not searched.
If startFrom < 0, it is considered as the offset from the end of the collection (startFrom:=startFrom+length). Note that even if startFrom is negative, the collection is still searched from left to right.
If startFrom = 0, the whole collection is searched (default).

Example

 var $col : Collection
 var $in : Boolean
 var $obj : Object
 $obj:=New object("value"; 10)
 $col:=New collection(1;2;"Henry";5;3;"Albert";6;4;"Alan";5;$obj)
 $in:=$col.includes(3) //True
 $in:=$col.includes(5;6) //True
 $in:=$col.includes("al@") //True
 $in:=$col.includes("Hello") //False
 $in:=$col.includes($obj)  //True
 $in:=$col.includes(New object("value"; 10)) //False

.indexOf()

History

Release	Changes
v16 R6	Added

.indexOf( toSearch : expression { ; startFrom : Integer } ) : Integer

Parameter	Type		Description
toSearch	expression	->	Expression to search in the collection
startFrom	Integer	->	Index to start the search at
Result	Integer	<-	Index of the first occurrence of toSearch in the collection, -1 if not found

Description

The .indexOf() function searches the toSearch expression among collection elements and returns the index of the first found occurrence, or -1 if it was not found.

In toSearch, pass the expression to find in the collection. You can pass:

a scalar value (text, number, boolean, date),
the null value,
an object or a collection reference.

toSearch must match exactly the element to find (the same rules as for the equality operator of the data type are applied).

Optionally, you can pass the index of collection from which to start the search in startFrom.

If startFrom >= the collection's length, -1 is returned, which means the collection is not searched.
If startFrom < 0, it is considered as the offset from the end of the collection (startFrom:=startFrom+length). Note: Even if startFrom is negative, the collection is still searched from left to right.
If startFrom = 0, the whole collection is searched (default).

Example

 var $col : Collection
 var $i : Integer
 $col:=New collection(1;2;"Henry";5;3;"Albert";6;4;"Alan";5)
 $i:=$col.indexOf(3) //$i=4
 $i:=$col.indexOf(5;5) //$i=9
 $i:=$col.indexOf("al@") //$i=5
 $i:=$col.indexOf("Hello") //$i=-1

.indices()

History

Release	Changes
v16 R6	Added

.indices( queryString : Text { ; ...value : any } ) : Collection

Parameter	Type		Description
queryString	Text	->	Search criteria
value	any	->	Value(s) to compare when using placeholder(s)
Result	Collection	<-	Element index(es) matching queryString in the collection

Description

The .indices() function works exactly the same as the .query() function but returns indexes, in the original collection, of object collection elements that match the queryString search conditions, and not elements themselves. Indexes are returned in ascending order.

The queryString parameter uses the following syntax:

propertyPath comparator value {logicalOperator propertyPath comparator value}

For a detailed description of the queryString and value parameters, please refer to the dataClass.query() function.

Example

 var $c; $icol : Collection
 $c:=New collection
 $c.push(New object("name";"Cleveland";"zc";35049))
 $c.push(New object("name";"Blountsville";"zc";35031))

 $c.push(New object("name";"Adger";"zc";35006))
 $c.push(New object("name";"Clanton";"zc";35046))
 $c.push(New object("name";"Clanton";"zc";35045))
 $icol:=$c.indices("name = :1";"Cleveland") // $icol=[0]
 $icol:=$c.indices("zc > 35040") // $icol=[0,3,4]

.insert()

History

Release	Changes
v16 R6	Added

.insert( index : Integer ; element : any ) : Collection

Parameter	Type		Description
index	Integer	->	Where to insert the element
element	any	->	Element to insert in the collection
Result	Collection	<-	Original collection containing inserted element

Description

The .insert() function inserts element at the specified index position in the collection instance and returns the edited collection.

In index, pass the position where you want the element to be inserted in the collection.

If index > the length of the collection, actual starting index will be set to the length of the collection.
If index <0, it is recalculated as index:=index+length (it is considered as the offset from the end of the collection).
If the calculated value is negative, index is set to 0.

Any type of element accepted by a collection can be inserted, even another collection.

Example

 var $col : Collection
 $col:=New collection("a";"b";"c";"d") //$col=["a","b","c","d"]
 $col.insert(2;"X") //$col=["a","b","X","c","d"]
 $col.insert(-2;"Y") //$col=["a","b","X","Y","c","d"]
 $col.insert(-10;"Hi") //$col=["Hi","a","b","X","Y","c","d"]

.join()

History

Release	Changes
v16 R6	Added

.join( delimiter : Text { ; option : Integer } ) : Text

Parameter	Type		Description
delimiter	Text	->	Separator to use between elements
option	Integer	->	`ck ignore null or empty`: ignore null and empty strings in the result
Result	Text	<-	String containing all elements of the collection, separated by delimiter

Description

The .join() function converts all elements of the collection to strings and concatenates them using the specified delimiter string as separator.The function returns the resulting string.

By default, null or empty elements of the collection are returned in the resulting string. Pass the ck ignore null or empty constant in the option parameter if you want to remove them from the resulting string.

Example

 var $c : Collection
 var $t1;$t2 : Text
 $c:=New collection(1;2;3;"Paris";Null;"";4;5)
 $t1:=$c.join("|") //1|2|3|Paris|null||4|5
 $t2:=$c.join("|";ck ignore null or empty) //1|2|3|Paris|4|5

.last()

History

Release	Changes
20	Added

.last() : any

Parameter	Type		Description
Result	any	<-	Last element of collection

Description

The .last() function returns the last element of the collection.

The function returns Undefined if the collection is empty.

Example

var $col; $emptyCol : Collection
var $last : Variant
$col:=New collection(10; 20; 30; "hello"; 50)
$last:=$col.last() // 50

$emptyCol:=New collection() //empty
// $last:=$emptyCol[$emptyCol.length-1] //returns an error
$last:=$emptyCol.last() // returns Undefined

.lastIndexOf()

History

Release	Changes
v16 R6	Added

.lastIndexOf( toSearch : expression { ; startFrom : Integer } ) : Integer

Parameter	Type		Description
toSearch	expression	->	The element that is to be searched for within the collection
startFrom	Integer	->	Index to start the search at
Result	Integer	<-	Index of last occurrence of toSearch in the collection, -1 if not found

Description

The .lastIndexOf() function searches the toSearch expression among collection elements and returns the index of the last occurrence, or -1 if it was not found.

In toSearch, pass the expression to find in the collection. You can pass:

a scalar value (text, number, boolean, date),
the null value,
an object or a collection reference.

toSearch must match exactly the element to find (the same rules as for the equality operator are applied).

Optionally, you can pass the index of collection from which to start a reverse search in startFrom.

If startFrom >= the collection's length minus one (coll.length-1), the whole collection is searched (default).
If startFrom < 0, it is recalculated as startFrom:=startFrom+length (it is considered as the offset from the end of the collection). If the calculated value is negative, -1 is returned (the collection is not searched). Note: Even if startFrom is negative, the collection is still searched from right to left.
If startFrom = 0, -1 is returned, which means the collection is not searched.

Example

 var $col : Collection
 var $pos1;$pos2;$pos3;$pos4;$pos5 : Integer
 $col:=Split string("a,b,c,d,e,f,g,h,i,j,e,k,e";",") //$col.length=13
 $pos1:=$col.lastIndexOf("e") //returns 12
 $pos2:=$col.lastIndexOf("e";6) //returns 4
 $pos3:=$col.lastIndexOf("e";15) //returns 12
 $pos4:=$col.lastIndexOf("e";-2) //returns 10
 $pos5:=$col.lastIndexOf("x") //returns -1

.length

History

Release	Changes
v16 R5	Added

.length : Integer

Description

The .length property returns the number of elements in the collection.

The .length property is initialized when the collection is created. Adding or removing elements updates the length, if necessary. This property is read-only (you cannot use it to set the size of the collection).

Example

 var $col : Collection //$col.length initialized to 0
 $col:=New collection("one";"two";"three") //$col.length updated to 3
 $col[4]:="five" //$col.length updated to 5
 $vSize:=$col.remove(0;3).length //$vSize=2

.map()

History

Release	Changes
19 R6	Support of formula
v16 R6	Added

.map( formula : 4D.Function { ; ...param : any } ) : Collection
.map( methodName : Text { ; ...param : any } ) : Collection

Parameter	Type		Description
formula	4D.Function	->	Formula object
methodName	Text	->	Name of a method
param	any	->	Parameter(s) to pass to formula or methodName
Result	Collection	<-	Collection of transformed values

Description

The .map() function creates a new collection based upon the result of the call of the formula 4D function or methodName method on each element of the original collection. Optionally, you can pass parameters to formula or methodName using the param parameter(s). .map() always returns a collection with the same size as the original collection, except if $1.stop was used (see below).

You designate the callback to be executed to evaluate collection elements using either:

formula (recommended syntax), a Formula object that can encapsulate any executable expressions, including functions and project methods;
or methodName, the name of a project method (text).

The callback receives the following parameters:

in $1.value: element value to be evaluated
in $2: param
in $N...: paramN...

It can set the following parameter(s):

(mandatory if you used a method) $1.result (any type): new transformed value to add to the resulting collection
$1.stop (Boolean, optional): true to stop the method callback. The returned value is the last calculated.

Example

var $c; $c2 : Collection
$c:=New collection(1; 4; 9; 10; 20)
$c2:=$c.map(Formula(Round(($1.value/$2)*100; 2)); $c.sum())
  //$c2=[2.27,9.09,20.45,22.73,45.45]

.max()

History

Release	Changes
v16 R6	Added

.max( { propertyPath : Text } ) : any

Parameter	Type		Description
propertyPath	Text	->	Object property path to be used for evaluation
Result	Boolean, Text, Number, Collection, Object, Date	<-	Maximum value in the collection

Description

The .max() function returns the element with the highest value in the collection (the last element of the collection as it would be sorted in ascending order using the .sort() function).

If the collection contains different types of values, the .max() function will return the maximum value within the last element type in the type list order (see .sort() description).

If the collection contains objects, pass the propertyPath parameter to indicate the object property whose maximum value you want to get.

If the collection is empty, .max() returns Undefined.

Example

 var $col : Collection
 $col:=New collection(200;150;55)
 $col.push(New object("name";"Smith";"salary";10000))
 $col.push(New object("name";"Wesson";"salary";50000))
 $col.push(New object("name";"Alabama";"salary";10500))
 $max:=$col.max() //{name:Alabama,salary:10500}
 $maxSal:=$col.max("salary") //50000
 $maxName:=$col.max("name") //"Wesson"

.min()

History

Release	Changes
v16 R6	Added

.min( { propertyPath : Text } ) : any

Parameter	Type		Description
propertyPath	Text	->	Object property path to be used for evaluation
Result	Boolean, Text, Number, Collection, Object, Date	<-	Minimum value in the collection

Description

The .min() function returns the element with the smallest value in the collection (the first element of the collection as it would be sorted in ascending order using the .sort() function).

If the collection contains different types of values, the .min() function will return the minimum value within the first element type in the type list order (see .sort() description).

If the collection contains objects, pass the propertyPath parameter to indicate the object property whose minimum value you want to get.

If the collection is empty, .min() returns Undefined.

Example

 var $col : Collection
 $col:=New collection(200;150;55)
 $col.push(New object("name";"Smith";"salary";10000))
 $col.push(New object("name";"Wesson";"salary";50000))
 $col.push(New object("name";"Alabama";"salary";10500))
 $min:=$col.min() //55
 $minSal:=$col.min("salary") //10000
 $minName:=$col.min("name") //"Alabama"

.multiSort()

History

Release	Changes
20 R3	Added

.multiSort() : Collection
.multiSort( colsToSort : Collection ) : Collection
.multiSort( formula : 4D.Function ; colsToSort : Collection ) : Collection

Parameter	Type		Description
formula	4D.Function	->	Formula object
colsToSort	Collection	->	Collection of collections and/or objects with {`collection`:colToSort;`order`:`ck ascending` or `ck descending`} properties
Result	Collection	<-	Original collection sorted

Description

The .multiSort() function enables you to carry out a multi-level synchronized sort on a set of collections.

If .multiSort() is called with no parameters, the function has the same effect as the .sort() function: the collection is sorted (only scalar values) in ascending order by default, according to their type. If the collection contains values of different types, they are first grouped by type and sorted afterwards. Types are returned in the following order:

null
booleans
strings
numbers
objects
collections
dates

Single-level synchronized sort

To sort several collections synchronously, just pass in colsToSort a collection of collections to sort. You can pass an unlimited number of collections. The original collection will be sorted in ascending order and all colsToSort collections will be sorted in a synchronized manner.

note

All colsToSort collections must have the same number of elements, otherwise an error is returned.

If you want to sort the collections in some other order than ascending, you must supply a formula (Formula object that defines the sort order. The return value should be a boolean that indicates the relative order of the two elements: True if $1.value is less than $1.value2, False if $1.value is greater than $1.value2. You can provide additional parameters to the formula if necessary.

The formula receives the following parameters:

$1 (object), where:
- $1.value (any type): first element value to be compared
- $1.value2 (any type): second element value to be compared
$2...$N (any type): extra parameters

Multi-level synchronized sort

Defining a multi-level synchronized sort requires that you pass an object containing {collection:colToSort;order:ck ascending or ck descending} properties instead of the colToSort itself for every collection to use as sub-level.

The sort levels are determined by the order in which the collections are passed in the colsToSort parameter: the position of a collection/order object in the syntax determines its sort level.

note

The .multiSort() function uses a stable sort algorithm.

Example 1

A simple synchronized sort of collections with different value types:

var $col;$col2;$col3 : Collection
$col:=["A"; "C"; "B"]
$col2:=[1; 2; 3]
$col3:=[["Jim"; "Philip"; "Maria"]; ["blue"; "green"]; ["11"; 22; "33"]]

$col.multiSort([$col2; $col3])
//$col=["A","B","C"]
//$col2=[1,3,2]
//$col3[0]=["Jim","Philip","Maria"]
//$col3[1]=["11",22,"33"]
//$col3[2]=["blue","green"]

Example 2

You want to sort three synchronized collections: city, country, and continent. You want an ascending sort of the first and the third collections, and synchronization for the second collection:

var $city : Collection
var $country : Collection
var $continent : Collection

$city:=["Paris"; "Lyon"; "Rabat"; "Eching"; "San Diego"]
$country:=["France"; "France"; "Morocco"; "Germany"; "US"]
$continent:=["Europe"; "Europe"; "Africa"; "Europe"; "America"]

$continent.multiSort([$country; {collection: $city; order: ck ascending}])
//$continent=["Africa","America","Europe","Europe","Europe"]
//$country=["Morocco","US","France","France","Germany"]
//$city=["Rabat","San Diego","Lyon","Paris","Eching"]

Example 3

You can also synchronize collections of objects.

var $name : Collection
var $address : Collection
$name:=[]
$name.push({firstname: "John"; lastname: "Smith"})
$name.push({firstname: "Alain"; lastname: "Martin"})
$name.push({firstname: "Jane"; lastname: "Doe"})
$name.push({firstname: "John"; lastname: "Doe"})
$address:=[]
$address.push({city: "Paris"; country: "France"})
$address.push({city: "Lyon"; country: "France"})
$address.push({city: "Eching"; country: "Germany"})
$address.push({city: "Berlin"; country: "Germany"})

$name.multiSort(Formula($1.value.firstname<$1.value2.firstname); [$address])
//"Alain Martin","Jane Doe","John Smith","John Doe"
//"Lyon France","Eching Germany","Paris France","Berlin Germany"

.orderBy()

History

Release	Changes
v16 R6	Added

.orderBy( ) : Collection
.orderBy( pathStrings : Text ) : Collection
.orderBy( pathObjects : Collection ) : Collection
.orderBy( ascOrDesc : Integer ) : Collection

Parameter	Type		Description
pathStrings	Text	->	Property path(s) on which to order the collection
pathObjects	Collection	->	Collection of criteria objects
ascOrDesc	Integer	->	`ck ascending` or `ck descending` (scalar values)
Result	Collection	<-	Ordered copy of the collection (shallow copy)

Description

The .orderBy() function returns a new collection containing all elements of the collection in the specified order.

This function returns a shallow copy, which means that objects or collections in both collections share the same reference. If the original collection is a shared collection, the returned collection is also a shared collection.

If you pass no parameter, the function orders scalar values in the collection in ascending order (other element types such as objects or collections are returned with an internal order). You can modify this automatic order by passing the ck ascending or ck descending constants in the ascOrDesc parameter (see below).

You can also pass a criteria parameter to define how the collection elements must be sorted. Three syntaxes are supported for this parameter:

pathStrings : Text (formula). Syntax: propertyPath1 {desc or asc}, propertyPath2 {desc or asc},... (default order: asc). pathStrings contains a formula made of 1 to x property paths and (optionally) sort orders, separated by commas. The order in which the properties are passed determines the sorting priority of the collection elements. By default, properties are sorted in ascending order. You can set the sort order of a property in the criteria string, separated from the property path by a single space: pass "asc" to sort in ascending order or "desc" in descending order.
pathObjects : Collection. You can add as many objects in the pathObjects collection as necessary. By default, properties are sorted in ascending order ("descending" is false). Each element of the collection contains an object structured in the following way:

{
    "propertyPath": string,

    "descending": boolean

}

ascOrDesc : Integer. You pass one of the following constants from the Objects and collections theme:

Constant Type Value Comment
ck ascending Longint 0 Elements are ordered in ascending order (default)
ck descending Longint 1 Elements are ordered in descending order

This syntax orders scalar values in the collection only (other element types such as objects or collections are returned unordered).

If the collection contains elements of different types, they are first grouped by type and sorted afterwards. Types are returned in the following order:

null
booleans
strings
numbers
objects
collections
dates

Example 1

Ordering a collection of numbers in ascending and descending order:

 var $c; $c2; $c3 : Collection
 $c:=New collection
 For($vCounter;1;10)
    $c.push(Random)
 End for
 $c2:=$c.orderBy(ck ascending)
 $c3:=$c.orderBy(ck descending)

Example 2

Ordering a collection of objects based on a text formula with property names:

 var $c; $c2 : Collection
 $c:=New collection
 For($vCounter;1;10)
    $c.push(New object("id";$vCounter;"value";Random))
 End for
 $c2:=$c.orderBy("value desc")
 $c2:=$c.orderBy("value desc, id")
 $c2:=$c.orderBy("value desc, id asc")

Ordering a collection of objects with a property path:

 var $c; $c2 : Collection
 $c:=New collection
 $c.push(New object("name";"Cleveland";"phones";New object("p1";"01";"p2";"02")))
 $c.push(New object("name";"Blountsville";"phones";New object("p1";"00";"p2";"03")))

 $c2:=$c.orderBy("phones.p1 asc")

Example 3

Ordering a collection of objects using a collection of criteria objects:

 var $crit; $c; $c2 : COllection
 $crit:=New collection
 $c:=New collection
 For($vCounter;1;10)
    $c.push(New object("id";$vCounter;"value";Random))
 End for
 $crit.push(New object("propertyPath";"value";"descending";True))
 $crit.push(New object("propertyPath";"id";"descending";False))
 $c2:=$c.orderBy($crit)

Ordering with a property path:

 var $crit; $c; $c2 : Collection
 $c:=New collection
 $c.push(New object("name";"Cleveland";"phones";New object("p1";"01";"p2";"02")))
 $c.push(New object("name";"Blountsville";"phones";New object("p1";"00";"p2";"03")))
 $crit:=New collection(New object("propertyPath";"phones.p2";"descending";True))
 $c2:=$c.orderBy($crit)

.orderByMethod()

History

Release	Changes
19 R6	Support of formula
v16 R6	Added

.orderByMethod( formula : 4D.Function { ; ...extraParam : expression } ) : Collection
.orderByMethod( methodName : Text { ; ...extraParam : expression } ) : Collection

Parameter	Type		Description
formula	4D.Function	->	Formula object
methodName	Text	->	Name of a method
extraParam	any	->	Parameter(s) to pass
Result	Collection	<-	Sorted copy of the collection (shallow copy)

Description

The .orderByMethod() function returns a new collection containing all elements of the collection in the order defined through the formula 4D function or methodName method.

You designate the callback to be executed to evaluate collection elements using either:

formula (recommended syntax), a Formula object that can encapsulate any executable expressions, including functions and project methods;
or methodName, the name of a project method (text).

In the callback, pass some code that compares two values and returns true if the first value is lower than the second value. You can provide extraParam parameters to the callback if necessary.

The callback receives the following parameters:

$1 (object), where:
- $1.value (any type): first element value to be compared
- $1.value2 (any type): second element value to be compared
- $2...$N (any type): extra parameters

If you used a method, it must set the following parameter:

$1.result (boolean): true if $1.value < $1.value2, false otherwise

Example 1

You want to sort a collection of strings in numerical order rather than alphabetical order:

 var $c; $c2; $c3 : Collection
 $c:=New collection
 $c.push("33";"4";"1111";"222")
 $c2:=$c.orderBy() //$c2=["1111","222","33","4"], alphabetical order
 $c3:=$c.orderByMethod(Formula(Num($1.value)<Num($1.value2))) // $c3=["4","33","222","1111"]

Example 2

You want to sort a collection of strings on their length:

 var $fruits; $c2 : Collection
 $fruits:=New collection("Orange";"Apple";"Grape";"pear";"Banana";"fig";"Blackberry";"Passion fruit")
 $c2:=$fruits.orderByMethod(Formula(Length(String($1.value))>Length(String($1.value2))))
  //$c2=[Passion fruit,Blackberry,Orange,Banana,Apple,Grape,pear,fig]

Example 3

You want to sort a collection by character code or language:

var $strings1; $strings2 : Collection
$strings1:=New collection("Alpha";"Charlie";"alpha";"bravo";"Bravo";"charlie")

//using the character code:
$strings2:=$strings1.orderByMethod(Function(sortCollection);sk character codes)
// result : ["Alpha","Bravo","Charlie","alpha","bravo","charlie"]

//using the language:
$strings2:=$strings1.orderByMethod(Function(sortCollection);sk strict)
// result : ["alpha","Alpha","bravo","Bravo","charlie","Charlie"]

The sortCollection method:

var $1 : Object
var $2: Integer // sort option

$1.result:=(Compare strings($1.value;$1.value2;$2)<0)

.pop()

History

Release	Changes
v16 R6	Added

.pop() : any

Parameter	Type		Description
Result	any	<-	Last element of collection

Description

The .pop() function removes the last element from the collection and returns it as the function result.

When applied to an empty collection, .pop() returns undefined.

Example

.pop(), used in conjunction with .push(), can be used to implement a first-in, last-out stack feature:

 var $stack : Collection
 $stack:=New collection //$stack=[]
 $stack.push(1;2) //$stack=[1,2]
 $stack.pop() //$stack=[1]  Returns 2
 $stack.push(New collection(4;5)) //$stack=[[1,[4,5]]
 $stack.pop() //$stack=[1]  Returns [4,5]
 $stack.pop() //$stack=[]  Returns 1

.push()

History

Release	Changes
v16 R6	Added

.push( element : any { ;...elementN } ) : Collection

Parameter	Type		Description
element	any	->	Element(s) to add to the collection
Result	Collection	<-	Original collection containing added elements

Description

The .push() function appends one or more element(s) to the end of the collection instance and returns the edited collection.

Example 1

 var $col : Collection
 $col:=New collection(1;2) //$col=[1,2]
 $col.push(3) //$col=[1,2,3]
 $col.push(6;New object("firstname";"John";"lastname";"Smith"))
  //$col=[1,2,3,6,{firstname:John,lastname:Smith}

Example 2

You want to sort the resulting collection:

 var $col; $sortedCol : Collection
 $col:=New collection(5;3;9) //$col=[5,3,9]
 $sortedCol:=$col.push(7;50).sort()
  //$col=[5,3,9,7,50]
  //$sortedCol=[3,5,7,9,50]

.query()

History

Release	Changes
20 R6	Support of queries using object or collection references
17 R5	Support of querySettings
v16 R6	Added

.query( queryString : Text ) : Collection
.query( queryString : Text ; ...value : any ) : Collection
.query( queryString : Text ; querySettings : Object ) : Collection

Parameter	Type		Description
queryString	Text	->	Search criteria
value	any	->	Value(s) to compare when using placeholder(s)
querySettings	Object	->	Query options: parameters, attributes
Result	Collection	<-	Element(s) matching queryString in the collection

Description

The .query() function returns all elements of a collection of objects that match the search conditions defined by queryString and (optionally) value or querySettings. If the original collection is a shared collection, the returned collection is also a shared collection.

An empty collection is returned if the collection in which the query is executed does not contain the searched value.

queryString parameter

The queryString parameter uses the following syntax:

propertyPath comparator value {logicalOperator propertyPath comparator value}

where:

propertyPath: path of property on which you want to execute the query. This parameter can be a simple name (for example "country") or any valid attribute path (for example "country.name".) In case of an attribute path whose type is Collection, [] notation is used to handle all the occurences (for example children[].age).
comparator: symbol that compares propertyPath and value. The following symbols are supported:

Comparison	Symbol(s)	Comment
Equal to	=, ==	Gets matching data, supports the wildcard (@), neither case-sensitive nor diacritic.
	===, IS	Gets matching data, considers the @ as a standard character, neither case-sensitive nor diacritic
Not equal to	#, !=	Supports the wildcard (@). Equivalent to "Not condition applied on a statement" (see below).
	!==, IS NOT	Considers the @ as a standard character
Not condition applied on a statement	NOT	Parenthesis are mandatory when NOT is used before a statement containing several operators. Equivalent to "Not equal to" (see below).
Less than	<
Greater than	>
Less than or equal to	<=
Greater than or equal to	>=
Included in	IN	Gets data equal to at least one of the values in a collection or in a set of values, supports the wildcard (@)

value: the value to compare to the current value of the property of each element in the collection. It can be any constant value expression matching the element's data type property or a placeholder. When using a constant value, the following rules must be respected:
- text type constant can be passed with or without simple quotes (see Using quotes below). To query a string within a string (a "contains" query), use the wildcard symbol (@) in value to isolate the string to be searched for as shown in this example: "@Smith@". The following keywords are forbidden for text constants: true, false.
- boolean type constants: true or false (case sensitive).
- numeric type constants: decimals are separated by a '.' (period).
- date type constants: "YYYY-MM-DD" format
- null constant: using the "null" keyword will find null and undefined properties.
- in case of a query with an IN comparator, value must be a collection, or values matching the type of the attribute path between [ ] separated by commas (for strings, " characters must be escaped with \).
logicalOperator: used to join multiple conditions in the query (optional). You can use one of the following logical operators (either the name or the symbol can be used):

Conjunction	Symbol(s)
AND	&, &&, and
OR	\|,\|\|, or

Using quotes

When you use quotes within queries, you must use single quotes ' ' inside the query and double quotes " " to enclose the whole query, otherwise an error is returned. For example:

"employee.name = 'smith' AND employee.firstname = 'john'"

Using parenthesis

You can use parentheses in the query to give priority to the calculation. For example, you can organize a query as follows:

"(employee.age >= 30 OR employee.age <= 65) AND (employee.salary <= 10000 OR employee.status = 'Manager')"

Using placeholders

4D allows you to use placeholders for propertyPath and value arguments within the queryString parameter. A placeholder is a parameter that you insert in query strings and that is replaced by another value when the query string is evaluated. The value of placeholders is evaluated once at the beginning of the query; it is not evaluated for each element.

Two types of placeholders can be used: indexed placeholders and named placeholders.

Indexed placeholders: parameters are inserted as :paramIndex (for example ":1", ":2"...) in queryString and their corresponding values are provided by the sequence of value parameter(s). You can use up to 128 value parameters.

Example:

$c:=$myCol.query(":1=:2";"city";"Chicago")

Named placeholders: parameters are inserted as :paramName (for example ":myparam") and their values are provided in the "attributes" and/or "parameters" objects in the querySettings parameter.

Example:

$o.attributes:={att:"city"}
$o.parameters:={name:"Chicago")
$c:=$myCol.query(":att=:name";$o)

You can mix all argument kinds in queryString. A queryString can contain, for propertyPath and value parameters:

direct values (no placeholders),
indexed placeholders and/or named placeholders.

Using placeholders in queries is recommended for the following reasons:

It prevents malicious code insertion: if you directly use user-filled variables within the query string, a user could modifiy the query conditions by entering additional query arguments. For example, imagine a query string like:

 $vquery:="status = 'public' & name = "+myname //user enters their name
 $result:=$col.query($vquery)

This query seems secured since non-public data are filtered. However, if the user enters in the myname area something like "smith OR status='private', the query string would be modified at the interpretation step and could return private data.

When using placeholders, overriding security conditions is not possible:

 $result:=$col.query("status='public' & name=:1";myname)

In this case if the user enters smith OR status='private' in the myname area, it will not be interpreted in the query string, but only passed as a value. Looking for a person named "smith OR status='private'" will just fail.

It prevents having to worry about formatting or character issues, especially when handling propertyPath or value parameters that might contain non-alphanumeric characters such as ".", "['...
It allows the use of variables or expressions in query arguments. Examples:

$result:=$col.query("address.city = :1 & name =:2";$city;$myVar+"@")
$result2:=$col.query("company.name = :1";"John's Pizzas")

Looking for null values

When you look for null values, you cannot use the placeholder syntax because the query engine considers null as an unexpected comparison value. For example, if you execute the following query:

$vSingles:=$colPersons.query("spouse = :1";Null) // will NOT work

You will not get the expected result because the null value will be evaluated by 4D as an error resulting from the parameter evaluation (for example, an attribute coming from another query). For these kinds of queries, you must use the direct query syntax:

$vSingles:=$colPersons.query("spouse = null") //correct syntax

Object or collection reference as value

You can query a collection using an object reference or a collection reference as the value parameter to compare. The query will match objects in the collection that refer (point to) the same instance of object or collection.

The following comparators are supported:

Comparison	Symbol(s)
Equal to	=, ==
Not equal to	#, !=

To build a query with an object or a collection reference, you must use the querySettings parameter syntax. Example with an object reference:

var $o1:={a: 1}
var $o2:={a: 1} //same object but another reference
var $o3:=$o1 //same object and reference

var $col; $colResult : Collection

$col:=[{o: $o1}; {o: $o2}; {o: $o3}]
$colResult:=$col.query("o = :v"; {parameters: {v: $o3}})
	//$colResult.length=2
	//$colResult[0].o=$o1 is true
	//$colResult[1].o=$o1 is true

Example with a collection reference:

$c1:=[1; 2; 3]
$c2:=[1; 2; 3] //same collection but another reference
$c3:=$c1 //same collection and reference

$col:=[{c: $c1}; {c: $c2}; {c: $c3}]
$col2:=$col.query("c = :v"; {parameters: {v: $c3}})
	//$col2.length=2
	//$col2[0].c=$c1 is true
	//$col2[1].c=$c1 is true

querySettings parameter

In the querySettings parameter, you can pass an object containing query placeholders as objects. The following properties are supported:

Property

Type

Description

parameters

Object

Named placeholders for values used in the queryString. Values are expressed as property / value pairs, where property is the placeholder name inserted for a value in the queryString (":placeholder") and value is the value to compare. You can mix indexed placeholders (values directly passed in value parameters) and named placeholder values in the same query.

attributes

Object

Named placeholders for attribute paths used in the queryString. Attributes are expressed as property / value pairs, where property is the placeholder name inserted for an attribute path in the queryString (":placeholder"), and value can be a string or a collection of strings. Each value is a path that can designate a property in an object of the collection

Type	Description
String	attributePath expressed using the dot notation, e.g. "name" or "user.address.zipCode"
Collection of strings	Each string of the collection represents a level of attributePath, e.g. ["name"] or ["user","address","zipCode"]. Using a collection allows querying on attributes with names that are not compliant with dot notation, e.g. ["4Dv17.1","en/fr"]

You can mix indexed placeholders (values directly passed in value parameters) and named placeholder values in the same query.

Example 1

 var $c; $c2; $c3 : Collection
 $c:=New collection
 $c.push(New object("name";"Cleveland";"zc";35049))
 $c.push(New object("name";"Blountsville";"zc";35031))
 $c.push(New object("name";"Adger";"zc";35006))
 $c.push(New object("name";"Clanton";"zc";35046))
 $c.push(New object("name";"Clanton";"zc";35045))
 $c2:=$c.query("name = :1";"Cleveland") //$c2=[{name:Cleveland,zc:35049}]
 $c3:=$c.query("zc > 35040") //$c3=[{name:Cleveland,zc:35049},{name:Clanton,zc:35046},{name:Clanton,zc:35045}]

Example 2

 var $c : Collection
 $c:=New collection
 $c.push(New object("name";"Smith";"dateHired";!22-05-2002!;"age";45))
 $c.push(New object("name";"Wesson";"dateHired";!30-11-2017!))
 $c.push(New object("name";"Winch";"dateHired";!16-05-2018!;"age";36))

 $c.push(New object("name";"Sterling";"dateHired";!10-5-1999!;"age";Null))
 $c.push(New object("name";"Mark";"dateHired";!01-01-2002!))

This example returns persons whose name contains "in":

 $col:=$c.query("name = :1";"@in@")
  //$col=[{name:Winch...},{name:Sterling...}]

This example returns persons whose name does not begin with a string from a variable (entered by the user, for example):

 $col:=$c.query("name # :1";$aString+"@")
  //if $astring="W"
  //$col=[{name:Smith...},{name:Sterling...},{name:Mark...}]

This example returns persons whose age is not known (property set to null or undefined):

 $col:=$c.query("age=null") //placeholders not allowed with "null"
  //$col=[{name:Wesson...},{name:Sterling...},{name:Mark...}]

This example returns persons hired more than 90 days ago:

 $col:=$c.query("dateHired < :1";(Current date-90))
  //$col=[{name:Smith...},{name:Sterling...},{name:Mark...}] if today is 01/10/2018

Example 3

Queries with dates:

$entitySelection:=ds.Employee.query("birthDate > :1";"1970-01-01")
$entitySelection:=ds.Employee.query("birthDate <= :1";Current date-10950)

info

More examples of queries can be found in the dataClass.query() page.

.reduce()

History

Release	Changes
19 R6	Support of formula
v16 R6	Added

.reduce( formula : 4D.Function { ; initValue : any { ; ...param : expression }} ) : any
.reduce( methodName : Text { ; initValue : any { ; ...param : expression }} ) : any

Parameter	Type		Description
formula	4D.Function	->	Formula object
methodName	Text	->	Name of a method
initValue	Text, Number, Object, Collection, Date, Boolean	->	Value to use as the first argument to the first call of formula or methodName
param	expression	->	Parameter(s) to pass
Result	Text, Number, Object, Collection, Date, Boolean	<-	Result of the accumulator value

Description

The .reduce() function applies the formula or methodName callback against an accumulator and each element in the collection (from left to right) to reduce it to a single value.

You designate the callback to be executed to evaluate collection elements using either:

formula (recommended syntax), a Formula object that can encapsulate any executable expressions, including functions and project methods;
or methodName, the name of a project method (text).

The callback takes each collection element and performs any desired operation to accumulate the result into $1.accumulator, which is returned in $1.value.

You can pass the value to initialize the accumulator in initValue. If omitted, $1.accumulator starts with Undefined.

The callback receives the following parameters:

in $1.value: element value to be processed
in $2: param
in $N...: paramN...

The callback sets the following parameter(s):

$1.accumulator: value to be modified by the function and which is initialized by initValue.
$1.stop (boolean, optional): true to stop the method callback. The returned value is the last calculated.

Example 1

var $c : Collection
$c:=New collection(5;3;5;1;3;4;4;6;2;2)
$r:=$c.reduce(Formula($1.accumulator*=$1.value); 1)  //returns 86400

Example 2

This example allows reducing several collection elements to a single one:

 var $c;$r : Collection
 $c:=New collection
 $c.push(New collection(0;1))
 $c.push(New collection(2;3))
 $c.push(New collection(4;5))
 $c.push(New collection(6;7))
 $r:=$c.reduce(Formula(Flatten)) //$r=[0,1,2,3,4,5,6,7]

With the following Flatten method:

 If($1.accumulator=Null)
    $1.accumulator:=New collection
 End if
 $1.accumulator.combine($1.value)

.reduceRight()

History

Release	Changes
20	Added

.reduceRight( formula : 4D.Function { ; initValue : any { ; ...param : expression }} ) : any
.reduceRight( methodName : Text { ; initValue : any { ; ...param : expression }} ) : any

Parameter	Type		Description
formula	4D.Function	->	Formula object
methodName	Text	->	Name of a method
initValue	Text, Number, Object, Collection, Date, Boolean	->	Value to use as the first argument to the first call of formula or methodName
param	expression	->	Parameter(s) to pass
Result	Text, Number, Object, Collection, Date, Boolean	<-	Result of the accumulator value

Description

The .reduceRight() function applies the formula or methodName callback against an accumulator and each element in the collection (from right to left) to reduce it to a single value.

You designate the callback to be executed to evaluate collection elements using either:

formula (recommended syntax), a Formula object that can encapsulate any executable expressions, including functions and project methods;
or methodName, the name of a project method (text).

The callback takes each collection element and performs any desired operation to accumulate the result into $1.accumulator, which is returned in $1.value.

You can pass the value to initialize the accumulator in initValue. If omitted, $1.accumulator starts with Undefined.

The callback receives the following parameters:

in $1.value: element value to be processed
in $2: param
in $N...: paramN...

The callback sets the following parameter(s):

$1.accumulator: value to be modified by the function and which is initialized by initValue.
$1.stop (boolean, optional): true to stop the method callback. The returned value is the last calculated.

Example 1

var $c : Collection
$c:=New collection(5;3;5;1;3;4;4;6;2;2)
$r:=$c.reduceRight(Formula($1.accumulator*=$1.value); 1)  //returns 86400

Example 2

This example allows reducing several collection elements to a single one:

 var $c;$r : Collection
 $c:=New collection
 $c.push(New collection(0;1))
 $c.push(New collection(2;3))
 $c.push(New collection(4;5))
 $c.push(New collection(6;7))
 $r:=$c.reduceRight(Formula(Flatten)) //$r=[6,7,4,5,2,3,0,1]

With the following Flatten method:

	//Flatten project method
 If($1.accumulator=Null)
    $1.accumulator:=New collection
 End if
 $1.accumulator.combine($1.value)

.remove()

History

Release	Changes
v16 R6	Added

.remove( index : Integer { ; howMany : Integer } ) : Collection

Parameter	Type		Description
index	Integer	->	Element at which to start removal
howMany	Integer	->	Number of elements to remove, or 1 element if omitted
Result	Collection	<-	Modified collection without removed element(s)

Description

The .remove() function removes one or more element(s) from the specified index position in the collection and returns the edited collection.

In index, pass the position where you want the element to be removed from the collection.

If index < 0, it is recalculated as index:=index+length (it is considered as the offset from the end of the collection).
If the calculated value < 0, index is set to 0.
If the calculated value > the length of the collection, index is set to the length.

In howMany, pass the number of elements to remove from index. If howMany is not specified, then one element is removed.

If you try to remove an element from an empty collection, the method does nothing (no error is generated).

Example

 var $col : Collection
 $col:=New collection("a";"b";"c";"d";"e";"f";"g";"h")
 $col.remove(3) // $col=["a","b","c","e","f","g","h"]
 $col.remove(3;2) // $col=["a","b","c","g","h"]
 $col.remove(-8;1) // $col=["b","c","g","h"]
 $col.remove(-3;1) // $col=["b","g","h"]

.resize()

History

Release	Changes
v16 R6	Added

.resize( size : Integer { ; defaultValue : any } ) : Collection

Parameter	Type		Description
size	Integer	->	New size of the collection
defaultValue	Number, Text, Object, Collection, Date, Boolean	->	Default value to fill new elements
Result	Collection	<-	Resized original collection

Description

The .resize() function sets the collection length to the specified new size and returns the resized collection.

If size < collection length, exceeding elements are removed from the collection.
If size > collection length, the collection length is increased to size.

By default, new elements are filled will null values. You can specify the value to fill in added elements using the defaultValue parameter.

Example

 var $c : Collection
 $c:=New collection
 $c.resize(10) // $c=[null,null,null,null,null,null,null,null,null,null]

 $c:=New collection
 $c.resize(10;0) // $c=[0,0,0,0,0,0,0,0,0,0]

 $c:=New collection(1;2;3;4;5)
 $c.resize(10;New object("name";"X")) //$c=[1,2,3,4,5,{name:X},{name:X},{name:X},{name:X},{name:X}]

 $c:=New collection(1;2;3;4;5)
 $c.resize(2) //$c=[1,2]

.reverse()

History

Release	Changes
v16 R6	Added

.reverse( ) : Collection

Parameter	Type		Description
Result	Collection	<-	Inverted copy of the collection

Description

The .reverse() function returns a deep copy of the collection with all its elements in reverse order. If the original collection is a shared collection, the returned collection is also a shared collection.

Example

 var $c; $c2 : Collection
 $c:=New collection(1;3;5;2;4;6)
 $c2:=$c.reverse() //$c2=[6,4,2,5,3,1]

.shift()

History

Release	Changes
v16 R6	Added

.shift() : any

Parameter	Type		Description
Result	any	<-	First element of collection

Description

The .shift() function removes the first element of the collection and returns it as the function result.

If the collection is empty, this method does nothing.

Example

 var $c : Collection
 var $val : Variant
 $c:=New collection(1;2;4;5;6;7;8)
 $val:=$c.shift()
  // $val=1
  // $c=[2,4,5,6,7,8]

.slice()

History

Release	Changes
v16 R6	Added

.slice( startFrom : Integer { ; end : Integer } ) : Collection

Parameter	Type		Description
startFrom	Integer	->	Start index (included)
end	Integer	->	End index (not included)
Result	Collection	<-	New collection containing sliced elements (shallow copy)

Description

The .slice() function returns a portion of a collection into a new collection, selected from startFrom index to end index (end not included). This function returns a shallow copy of the collection. If the original collection is a shared collection, the returned collection is also a shared collection.

The returned collection contains the element specified by startFrom and all subsequent elements up to, but not including, the element specified by end. If only the startFrom parameter is specified, the returned collection contains all elements from startFrom to the last element of the original collection.

If startFrom < 0, it is recalculated as startFrom:=startFrom+length (it is considered as the offset from the end of the collection).
If the calculated value < 0, startFrom is set to 0.
If end < 0 , it is recalculated as end:=end+length.
If end < startFrom (passed or calculated values), the method does nothing.

Example

 var $c; $nc : Collection
 $c:=New collection(1;2;3;4;5)
 $nc:=$c.slice(0;3) //$nc=[1,2,3]
 $nc:=$c.slice(3) //$nc=[4,5]
 $nc:=$c.slice(1;-1) //$nc=[2,3,4]
 $nc:=$c.slice(-3;-2) //$nc=[3]

.some()

History

Release	Changes
19 R6	Support of formula
v16 R6	Added

.some( { startFrom : Integer ; } formula : 4D.Function { ; ...param : any } ) : Boolean
.some( { startFrom : Integer ; } methodName : Text { ; ...param : any } ) : Boolean

Parameter	Type		Description

Description

The .some() function returns true if at least one element in the collection successfully passed a test implemented in the provided formula or methodName code.

You designate the 4D code (callback) to be executed to evaluate collection elements using either:

formula (recommended syntax), a Formula object that can encapsulate any executable expressions, including functions and project methods;
or methodName, the name of a project method (text).

The callback receives the following parameters:

in $1.value: element value to be processed
in $2: param
in $N...: paramN...

It can set the following parameter(s):

(mandatory if you used a method) $1.result (boolean): true if the element value evaluation is successful, false otherwise.
$1.stop (boolean, optional): true to stop the method callback. The returned value is the last calculated.

In any case, at the point where .some() function encounters the first collection element returning true, it stops calling the callback and returns true.

By default, .some() tests the whole collection. Optionally, you can pass the index of an element from which to start the test in startFrom.

If startFrom >= the collection's length, False is returned, which means the collection is not tested.
If startFrom < 0, it is considered as the offset from the end of the collection.
If startFrom = 0, the whole collection is searched (default).

Example

You want to know if at least one collection value is >0.

 var $c : Collection
 var $b : Boolean
 $c:=New collection
 $c.push(-5;-3;-1;-4;-6;-2)
 $b:=$c.some(Formula($1.value>0)) // $b=false
 $c.push(1)
 $b:=$c.some(Formula($1.value>0)) // $b=true

 $c:=New collection
 $c.push(1;-5;-3;-1;-4;-6;-2)
 $b:=$c.some(Formula($1.value>0)) //$b=true
 $b:=$c.some(1;Formula($1.value>0)) //$b=false

.sort()

History

Release	Changes
19 R6	Support of formula
v16 R6	Added

.sort() : Collection
.sort( formula : 4D.Function { ; ...extraParam : any } ) : Collection
.sort( methodName : Text { ; ...extraParam : any } ) : Collection

Parameter	Type		Description
formula	4D.Function	->	Formula object
methodName	Text	->	Name of a method
extraParam	any	->	Parameter(s) for the method
Result	Collection	<-	Original collection sorted

Description

The .sort() function sorts the elements of the original collection and also returns the sorted collection .

If .sort() is called with no parameters, only scalar values (number, text, date, booleans) are sorted. Elements are sorted by default in ascending order, according to their type. If the collection contains elements of different types, they are first grouped by type and sorted afterwards. Types are returned in the following order:

null
booleans
strings
numbers
objects
collections
dates

If you want to sort the collection elements in some other order or sort any type of element, you must supply in formula (Formula object) or methodName (Text) a callback that defines the sort order. The return value should be a boolean that indicates the relative order of the two elements: True if $1.value is less than $1.value2, False if $1.value is greater than $1.value2. You can provide additional parameters to the callback if necessary.

The callback receives the following parameters:

$1 (object), where:
- $1.value (any type): first element value to be compared
- $1.value2 (any type): second element value to be compared
$2...$N (any type): extra parameters

If you used a method, you must set the folllowing parameter:

$1.result (boolean): true if $1.value < $1.value2, false otherwise.

Example 1

 var $col; $col2 : Collection
 $col:=New collection("Tom";5;"Mary";3;"Henry";1;"Jane";4;"Artie";6;"Chip";2)
 $col2:=$col.sort() // $col2=["Artie","Chip","Henry","Jane","Mary","Tom",1,2,3,4,5,6]
  // $col=["Artie","Chip","Henry","Jane","Mary","Tom",1,2,3,4,5,6]

Example 2

 var $col; $col2 : Collection
 $col:=New collection(10;20)
 $col2:=$col.push(5;3;1;4;6;2).sort() //$col2=[1,2,3,4,5,6,10,20]

Example 3

var $col; $col2; $col3 : Collection
$col:=New collection(33;4;66;1111;222)
$col2:=$col.sort() //numerical sort: [4,33,66,222,1111]
$col3:=$col.sort(Formula(String($1.value)<String($1.value2))) //alphabetical sort: [1111,222,33,4,66]

.sum()

History

Release	Changes
v16 R6	Added

.sum( { propertyPath : Text } ) : Real

Parameter	Type		Description
propertyPath	Text	->	Object property path to be used for calculation
Result	Real	<-	Sum of collection values

Description

The .sum() function returns the sum for all values in the collection instance.

Only numerical elements are taken into account for the calculation (other element types are ignored).

If the collection contains objects, pass the propertyPath parameter to indicate the object property to take into account.

.sum() returns 0 if:

the collection is empty,
the collection does not contain numerical elements,
propertyPath is not found in the collection.

Example 1

 var $col : Collection
 var $vSum : Real
 $col:=New collection(10;20;"Monday";True;2)
 $vSum:=$col.sum() //32

Example 2

 var $col : Collection
 var $vSum : Real
 $col:=New collection
 $col.push(New object("name";"Smith";"salary";10000))
 $col.push(New object("name";"Wesson";"salary";50000))
 $col.push(New object("name";"Gross";"salary";10500,5))
 $vSum:=$col.sum("salary") //$vSum=70500,5

.unshift()

History

Release	Changes
v16 R6	Added

.unshift( value : any { ;...valueN : any } ) : Collection

Parameter	Type		Description
value	Text, Number, Object, Collection, Date	->	Value(s) to insert at the beginning of the collection
Result	Real	<-	Collection containing added element(s)

Description

The .unshift() function inserts the given value(s) at the beginning of the collection and returns the modified collection.

If several values are passed, they are inserted all at once, which means that they appear in the resulting collection in the same order as in the argument list.

Example

 var $c : Collection
 $c:=New collection(1;2)
 $c.unshift(4) // $c=[4,1,2]
 $c.unshift(5) //$c=[5,4,1,2]
 $c.unshift(6;7) // $c=[6,7,5,4,1,2]

Constant	Type	Value	Comment
ck ascending	Longint	0	Elements are ordered in ascending order (default)
ck descending	Longint	1	Elements are ordered in descending order

Example​

Summary​

.at()​

Description​

Example​

.average()​

Description​

Example 1​

Example 2​

.clear()​

Description​

Example​

.combine()​

Description​

Example​

.concat()​

Description​

Example​

.copy()​

Description​

Example 1​

Example 2​

Example 3​

Example 4​

.count()​

Description​

Example​

.countValues()​

Description​

Example 1​

Example 2​

Example 3​

.distinct()​

Description​

Examples​

.equal()​

Description​

Example​

.every()​

Description​

Example 1​

Example 2​

.extract()​

Description​

Example 1​

Example 2​

.fill()​

Description​

Example​

.filter()​

Description​

Example 1​

Example 2​

.find()​

Description​

Example 1​

Example 2​

.findIndex()​

Description​

Example​

.first()​

Description​

Example​

.flat()​

Description​

Example​

.flatMap()​

Description​

Example 1​

Example 2​

Example 3​

.includes()​

Description​

Example​

.indexOf()​

Description​

Example​

.indices()​

Description​

Example​

Example

Summary

.at()

Description

Example

.average()

Description

Example 1

Example 2

.clear()

Description

Example

.combine()

Description

Example

.concat()

Description

Example

.copy()

Description

Example 1

Example 2

Example 3

Example 4

.count()

Description

Example

.countValues()

Description

Example 1

Example 2

Example 3

.distinct()

Description

Examples

.equal()

Description

Example

.every()

Description

Example 1

Example 2

.extract()

Description

Example 1

Example 2

.fill()

Description

Example

.filter()

Description

Example 1

Example 2

.find()

Description

Example 1

Example 2

.findIndex()

Description

Example

.first()

Description

Example

.flat()

Description

Example

.flatMap()

Description

Example 1

Example 2

Example 3

.includes()

Description

Example

.indexOf()

Description

Example

.indices()

Description

Example