Version: 19

Entity

An entity is an instance of a Dataclass, like a record of the table matching the dataclass in its associated datastore. It contains the same attributes as the dataclass as well as the data values and specific properties and functions.

Summary


.attributeName : any stores the attribute value for the entity
.clone() : 4D.Entity creates in memory a new entity referencing the same record as the original entity
.diff( entityToCompare : 4D.Entity { ; attributesToCompare : Collection } ) : Collection compares the contents of two entities and returns their differences
.drop( {mode : Integer} ) : Object deletes the data contained in the entity from the datastore
.first(): 4D.Entity returns a reference to the entity in first position of the entity selection which the entity belongs to
.fromObject( filler : Object ) fills an entity with the filler content
.getDataClass() : 4D.DataClass returns the dataclass of the entity
.getKey( { mode : Integer } ) : Text .getKey( { mode : Integer } ) : Integer returns the primary key value of the entity
.getSelection(): 4D.EntitySelection returns the entity selection which the entity belongs to
.getStamp() : Integer returns the current value of the stamp of the entity
.indexOf( { entitySelection : 4D.EntitySelection } ) : Integer returns the position of the entity in an entity selection
.isNew() : Boolean returns True if the entity to which it is applied has just been created and has not yet been saved in the datastore
.last() : 4D.Entity returns a reference to the entity in last position of the entity selection which the entity belongs to
.lock( { mode : Integer } ) : Object puts a pessimistic lock on the record referenced by the entity
.next() : 4D.Entity returns a reference to the next entity in the entity selection which the entity belongs to
.previous() : 4D.Entity returns a reference to the previous entity in the entity selection which the entity belongs to
.reload() : Object reloads the content of the entity in memory
.save( { mode : Integer } ) : Object saves the changes made to the entity
.toObject() : Object .toObject( filterString : Text { ; options : Integer} ) : Object .toObject( filterCol : Collection { ; options : Integer } ) : Object returns an object which has been built from the entity
.touched() : Boolean tests whether or not an entity attribute has been modified since the entity was loaded into memory or saved
.touchedAttributes() : Collection returns the names of the attributes that have been modified since the entity was loaded into memory
.unlock() : Object removes the pessimistic lock on the record matching the entity

.attributeName

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.attributeName : any

Description

Any dataclass attribute is available as a property of an entity, which stores the attribute value for the entity.

Dataclass attributes can also be reached using the alternate syntax with [ ].

The attribute value type depends on the attribute kind (relation or storage):

If attributeName kind is storage: .attributeName returns a value of the same type as attributeName.
If attributeName kind is relatedEntity: .attributeName returns the related entity. Values of the related entity are directly available through cascading properties, for example "myEntity.employer.employees[0].lastname".
If attributeName kind is relatedEntities: .attributeName returns a new entity selection of related entities. Duplications are removed (an unordered entity selection is returned).

Example

 var $myEntity : cs.EmployeeEntity
 $myEntity:=ds.Employee.new() //Create a new entity
 $myEntity.name:="Dupont" // assign 'Dupont' to the 'name' attribute
 $myEntity.firstname:="John" //assign 'John' to the 'firstname' attribute
 $myEntity.save() //save the entity

.clone()

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.clone() : 4D.Entity

Parameter	Type		Description
Result	4D.Entity	<-	New entity referencing the record

Description

The .clone() function creates in memory a new entity referencing the same record as the original entity. This function allows you to update entities separately.

Keep in mind that any modifications done to entities will be saved in the referenced record only when the .save( ) function is executed.

This function can only be used with entities already saved in the database. It cannot be called on a newly created entity (for which .isNew() returns True).

Example

 var $emp; $empCloned : cs.EmployeeEntity
 $emp:=ds.Employee.get(672)
 $empCloned:=$emp.clone()

 $emp.lastName:="Smith" //Updates done on $emp are not done on $empCloned

.diff()

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.diff( entityToCompare : 4D.Entity { ; attributesToCompare : Collection } ) : Collection

Parameter	Type		Description
entityToCompare	4D.Entity	->	Entity to be compared with the original entity
attributesToCompare	Collection	->	Name of attributes to be compared
Result	Collection	<-	Differences between the entities

Description

The .diff() function compares the contents of two entities and returns their differences.

In entityToCompare, pass the entity to be compared to the original entity.

In attributesToCompare, you can designate specific attributes to compare. If provided, the comparison is done only on the specified attributes. If not provided, all differences between the entities are returned.

The differences are returned as a collection of objects whose properties are:

Property name	Type	Description
attributeName	String	Name of the attribute
value	any - Depends on attribute type	Value of the attribute in the entity
otherValue	any - Depends on attribute type	Value of the attribute in entityToCompare

Only attributes with different values are included in the collection. If no differences are found, .diff() returns an empty collection.

The function applies for properties whose kind is storage or relatedEntity. In case a related entity has been updated (meaning the foreign key), the name of the related entity and its primary key name are returned as attributeName properties (value and otherValue are empty for the related entity name).

If one of the compared entities is Null, an error is raised.

Example 1

 var $diff1; $diff2 : Collection
 employee:=ds.Employee.query("ID=1001").first()
 $clone:=employee.clone()

 employee.firstName:="MARIE"
 employee.lastName:="SOPHIE"
 employee.salary:=500
 $diff1:=$clone.diff(employee) // All differences are returned
 $diff2:=$clone.diff(employee;New collection"firstName";"lastName"))
  // Only differences on firstName and lastName are returned

$diff1:

[
    {
        "attributeName": "firstName",
        "value": "Natasha",
        "otherValue": "MARIE"
    },
    {
        "attributeName": "lastName",
        "value": "Locke",
        "otherValue": "SOPHIE"
    },
    {
        "attributeName": "salary",
        "value": 66600,
        "otherValue": 500
    }
]
$diff2:

[
    {
        "attributeName": "firstName",
        "value": "Natasha",
        "otherValue": "MARIE"
    },
    {
        "attributeName": "lastName",
        "value": "Locke",
        "otherValue": "SOPHIE"
    }
]

Example 2

 var vCompareResult1; vCompareResult2; vCompareResult3; $attributesToInspect : Collection
 vCompareResult1:=New collection
 vCompareResult2:=New collection
 vCompareResult3:=New collection
 $attributesToInspect:=New collection

 $e1:=ds.Employee.get(636)
 $e2:=ds.Employee.get(636)

 $e1.firstName:=$e1.firstName+" update"
 $e1.lastName:=$e1.lastName+" update"

 $c:=ds.Company.get(117)
 $e1.employer:=$c
 $e2.salary:=100

 $attributesToInspect.push("firstName")
 $attributesToInspect.push("lastName")

 vCompareResult1:=$e1.diff($e2)
 vCompareResult2:=$e1.diff($e2;$attributesToInspect)
 vCompareResult3:=$e1.diff($e2;$e1.touchedAttributes())

vCompareResult1 (all differences are returned):

[
    {
        "attributeName": "firstName",
        "value": "Karla update",
        "otherValue": "Karla"
    },
    {
        "attributeName": "lastName",
        "value": "Marrero update",
        "otherValue": "Marrero"
    },
    {
        "attributeName": "salary",
        "value": 33500,
        "otherValue": 100
    },
    {
        "attributeName": "employerID",
        "value": 117,
        "otherValue": 118
    },
  {
        "attributeName": "employer",
        "value": "[object Entity]",// Entity 117 from Company
        "otherValue": "[object Entity]"// Entity 118 from Company
    }
]

vCompareResult2 (only differences on $attributesToInspect are returned)

[
    {
        "attributeName": "firstName",
        "value": "Karla update",
        "otherValue": "Karla"
    },
    {
        "attributeName": "lastName",
        "value": "Marrero update",
        "otherValue": "Marrero"
    }
]

vCompareResult3 (only differences on $e1 touched attributes are returned)

[
    {
        "attributeName": "firstName",
        "value": "Karla update",
        "otherValue": "Karla"
    },
    {
        "attributeName": "lastName",
        "value": "Marrero update",
        "otherValue": "Marrero"
    },
    {
        "attributeName": "employerID",
        "value": 117,
        "otherValue": 118
    },
     {
        "attributeName": "employer",
        "value": "[object Entity]",// Entity 117 from Company
        "otherValue": "[object Entity]"// Entity 118 from Company

    }
]

.drop()

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.drop( {mode : Integer} ) : Object

Parameter	Type		Description
mode	Integer	->	`dk force drop if stamp changed`: Forces the drop even if the stamp has changed
Result	Object	<-	Result of drop operation

Description

The .drop() function deletes the data contained in the entity from the datastore, from the table related to its Dataclass. Note that the entity remains in memory.

In a multi-user or multi-process application, the .drop() function is executed under an "optimistic lock" mechanism, wherein an internal locking stamp is automatically incremented each time the record is saved.

By default, if the mode parameter is omitted, the function will return an error (see below) if the same entity was modified (i.e. the stamp has changed) by another process or user in the meantime.

Otherwise, you can pass the dk force drop if stamp changed option in the mode parameter: in this case, the entity is dropped even if the stamp has changed (and the primary key is still the same).

Result

The object returned by .drop( ) contains the following properties:

Property		Type	Description
success		boolean	true if the drop action is successful, false otherwise.
			Available only in case of error:
status(*)		number	Error code, see below
statusText(*)		text	Description of the error, see below
			Available only in case of pessimistic lock error:
LockKindText		text	"Locked by record"
lockInfo		object	Information about the lock origin
	task_id	number	Process id
	user_name	text	Session user name on the machine
	user4d_alias	text	User alias if defined by `SET USER ALIAS`, otherwise user name in the 4D directory
	host_name	text	Machine name
	task_name	text	Process name
	client_version	text
			Available only in case of serious error (serious error can be trying to duplicate a primary key, disk full...):
errors		collection of objects
	message	text	Error message
	component signature	text	internal component signature (e.g. "dmbg" stands for the database component)
	errCode	number	Error code

(*) The following values can be returned in the status and statusText properties of Result object in case of error:

Constant	Value	Comment
`dk status entity does not exist anymore`	5	The entity no longer exists in the data. This error can occur in the following cases: the entity has been dropped (the stamp has changed and the memory space is now free) the entity has been dropped and replaced by another one with another primary key (the stamp has changed and a new entity now uses the memory space). When using entity.drop( ), this error can be returned when dk force drop if stamp changed option is used. When using entity.lock( ), this error can be returned when dk reload if stamp changed option is used Associated statusText: "Entity does not exist anymore"
`dk status locked`	3	The entity is locked by a pessimistic lock. Associated statusText: "Already locked"
`dk status serious error`	4	A serious error is a low-level database error (e.g. duplicated key), a hardware error, etc. Associated statusText: "Other error"
`dk status stamp has changed`	2	The internal stamp value of the entity does not match the one of the entity stored in the data (optimistic lock). with `.save( )`: error only if the `dk auto merge` option is not used with `.drop( )`: error only if the `dk force drop if stamp changed` option is not used with `.lock( )`: error only if the `dk reload if stamp changed` option is not used Associated statusText: "Stamp has changed"

Example 1

Example without dk force drop if stamp changed option:

 var $employees : cs.EmployeeSelection
 var $employee : cs.EmployeeEntity
 var $status : Object
 $employees:=ds.Employee.query("lastName=:1";"Smith")
 $employee:=$employees.first()
 $status:=$employee.drop()
 Case of
    :($status.success)
       ALERT("You have dropped "+$employee.firstName+" "+$employee.lastName) //The dropped entity remains in memory
    :($status.status=dk status stamp has changed)
       ALERT($status.statusText)
 End case

Example 2

Example with dk force drop if stamp changed option:

 var $employees : cs.EmployeeSelection
 var $employee : cs.EmployeeEntity
 var $status : Object
 $employees:=ds.Employee.query("lastName=:1";"Smith")
 $employee:=$employees.first()
 $status:=$employee.drop(dk force drop if stamp changed)
 Case of
    :($status.success)
       ALERT("You have dropped "+$employee.firstName+" "+$employee.lastName) //The dropped entity remains in memory
    :($status.status=dk status entity does not exist anymore)
       ALERT($status.statusText)
 End case

.first()

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.first(): 4D.Entity

Parameter	Type		Description
Result	4D.Entity	<-	Reference to first entity of an entity selection (Null if not found)

Description

The .first() function returns a reference to the entity in first position of the entity selection which the entity belongs to.

If the entity does not belong to any existing entity selection (i.e. .getSelection( ) returns Null), the function returns a Null value.

Example

 var $employees : cs.EmployeeSelection
 var $employee; $firstEmployee : cs.EmployeeEntity
 $employees:=ds.Employee.query("lastName = :1";"H@") //This entity selection contains 3 entities
 $employee:=$employees[2]
 $firstEmployee:=$employee.first() //$firstEmployee is the first entity of the $employees entity selection

.fromObject()

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.fromObject( filler : Object )

Parameter	Type		Description
filler	Object	->	Object from which to fill the entity

Description

The .fromObject() function fills an entity with the filler content.

This function modifies the original entity.

The mapping between the object and the entity is done on the attribute names:

If a property of the object does not exist in the dataclass, it is ignored.
Data types must be equivalent. If there is a type mismatch between the object and dataclass, 4D tries to convert the data whenever possible (see Converting data types), otherwise the attribute is left untouched.
The primary key can be given as is or with a "__KEY" property (filled with the primary key value). If it does not already exist in the dataclass, the entity is created with the given value when .save() is called. If the primary key is not given, the entity is created and the primary key value is assigned with respect to database rules. The auto-increment is only computed if the primary key is null.

filler can handle a related entity under the following conditions:

filler contains the foreign key itself, or
filler contains a property object with the same name as the related entity, containing a single property named "__KEY".
if the related entity does not exist, it is ignored.

Example

With the following $o object:

{
    "firstName": "Mary",
    "lastName": "Smith",
    "salary": 36500,
    "birthDate": "1958-10-27T00:00:00.000Z",
    "woman": true,
    "managerID": 411,// relatedEntity given with PK
    "employerID": 20 // relatedEntity given with PK
}

The following code will create an entity with manager and employer related entities.

 var $o : Object
 var $entity : cs.EmpEntity
 $entity:=ds.Emp.new()
 $entity.fromObject($o)
 $entity.save()

You could also use a related entity given as an object:

{
    "firstName": "Marie",
    "lastName": "Lechat",
    "salary": 68400,
    "birthDate": "1971-09-03T00:00:00.000Z",
    "woman": false,
    "employer": {// relatedEntity given as an object
        "__KEY": "21"
    },
    "manager": {// relatedEntity given as an object
        "__KEY": "411"
    }
}

.getDataClass()

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.getDataClass() : 4D.DataClass

Parameter	Type		Description
Result	4D.DataClass	<-	DataClass object to which the entity belongs

Description

The .getDataClass() function returns the dataclass of the entity. This function is useful when writing generic code.

Example

The following generic code duplicates any entity:

  //duplicate_entity method
  //duplicate_entity($entity)

 #DECLARE($entity : 4D.Entity)  
 var $entityNew : 4D.Entity
 var $status : Object

 $entityNew:=$entity.getDataClass().new() //create a new entity in the parent dataclass
 $entityNew.fromObject($entity.toObject()) //get all attributes
 $entityNew[$entity.getDataClass().getInfo().primaryKey]:=Null //reset the primary key
 $status:=$entityNew.save() //save the duplicated entity

.getKey()

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.getKey( { mode : Integer } ) : Text
.getKey( { mode : Integer } ) : Integer

Parameter	Type		Description
mode	Integer	->	`dk key as string`: primary key is returned as a string, no matter the primary key type
Result	Text	<-	Value of the text primary key of the entity
Result	Integer	<-	Value of the numeric primary key of the entity

Description

The .getKey() function returns the primary key value of the entity.

Primary keys can be numbers (Integer) or strings. You can "force" the returned primary key value to be a string, no matter the actual primary key type, by passing the dk key as string option in the mode parameter.

Example

 var $employees : cs.EmployeeSelection
 var $employee : cs.EmployeeEntity
 $employees:=ds.Employee.query("lastName=:1";"Smith")
 $employee:=$employees[0]
 ALERT("The primary key is "+$employee.getKey(dk key as string))

.getSelection()

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.getSelection(): 4D.EntitySelection

Parameter	Type		Description
Result	4D.EntitySelection	<-	Entity selection to which the entity belongs (Null if not found)

Description

The .getSelection() function returns the entity selection which the entity belongs to.

If the entity does not belong to an entity selection, the function returns Null.

Example

 var $emp : cs.EmployeeEntity
 var $employees; $employees2 : cs.EmployeeSelection
 $emp:=ds.Employee.get(672) // This entity does not belong to any entity selection
 $employees:=$emp.getSelection() // $employees is Null

 $employees2:=ds.Employee.query("lastName=:1";"Smith") //This entity selection contains 6 entities
 $emp:=$employees2[0]  // This entity belongs to an entity selection

 ALERT("The entity selection contains "+String($emp.getSelection().length)+" entities")

.getStamp()

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.getStamp() : Integer

Parameter	Type		Description
Result	Integer	<-	Stamp of the entity (0 if entity has just been created)

Description

The .getStamp() function returns the current value of the stamp of the entity.

The internal stamp is automatically incremented by 4D each time the entity is saved. It manages concurrent user access and modifications to the same entities (see Entity locking).

For a new entity (never saved), the function returns 0. To know if an entity has just been created, it is recommended to use .isNew().

Example

 var $entity : cs.EmployeeEntity
 var $stamp : Integer

 $entity:=ds.Employee.new()
 $entity.lastname:="Smith"
 $entity.save()
 $stamp:=$entity.getStamp() //$stamp=1

 $entity.lastname:="Wesson"
 $entity.save()
 $stamp:=$entity.getStamp() //$stamp=2

.indexOf()

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.indexOf( { entitySelection : 4D.EntitySelection } ) : Integer

Parameter	Type		Description
entitySelection	4D.EntitySelection	->	Position of the entity is given according to this entity selection
Result	Integer	<-	Position of the entity in an entity selection

Description

The .indexOf() function returns the position of the entity in an entity selection.

By default if the entitySelection parameter is omitted, the function returns the entity's position within its own entity selection. Otherwise, it returns the position of the entity within the specified entitySelection.

The resulting value is included between 0 and the length of the entity selection -1.

If the entity does not have an entity selection or does not belong to entitySelection, the function returns -1.
If entitySelection is Null or does not belong to the same dataclass as the entity, an error is raised.

Example

 var $employees : cs.EmployeeSelection
 var $employee : cs.EmployeeEntity
 $employees:=ds.Employee.query("lastName = :1";"H@") //This entity selection contains 3 entities
 $employee:=$employees[1] //This entity belongs to an entity selection
 ALERT("The index of the entity in its own entity selection is "+String($employee.indexOf())) //1

 $employee:=ds.Employee.get(725) //This entity does not belong to an entity selection
 ALERT("The index of the entity is "+String($employee.indexOf())) // -1

.isNew()

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.isNew() : Boolean

Parameter	Type		Description
Result	Boolean	<-	True if entity has just been created and not yet saved. Otherwise, False.

Description

The .isNew() function returns True if the entity to which it is applied has just been created and has not yet been saved in the datastore. Otherwise, it returns False.

Example

 var $emp : cs.EmployeeEntity

 $emp:=ds.Employee.new()

 If($emp.isNew())
    ALERT("This is a new entity")
 End if

.last()

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.last() : 4D.Entity

Parameter	Type		Description
Result	4D.Entity	<-	Reference to last entity of an entity selection (Null if not found)

Description

The .last() function returns a reference to the entity in last position of the entity selection which the entity belongs to.

If the entity does not belong to any existing entity selection (i.e. .getSelection( ) returns Null), the function returns a Null value.

Example

 var $employees : cs.EmployeeSelection
 var $employee; $lastEmployee : cs.EmployeeEntity
 $employees:=ds.Employee.query("lastName = :1";"H@") //This entity selection contains 3 entities
 $employee:=$employees[0]
 $lastEmployee:=$employee.last() //$lastEmployee is the last entity of the $employees entity selection

.lock()

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.lock( { mode : Integer } ) : Object

Parameter	Type		Description
mode	Integer	->	`dk reload if stamp changed`: Reload before locking if stamp changed
Result	Object	<-	Result of lock operation

Description

The .lock() function puts a pessimistic lock on the record referenced by the entity. The lock is set for a record and all the references of the entity in the current process.

Other processes will see this record as locked (the result.success property will contain False if they try to lock the same entity using this function). Only functions executed in the "locking" session are allowed to edit and save the attributes of the entity. The entity can be loaded as read-only by other sessions, but they will not be able to enter and save values.

A locked record is unlocked:

when the unlock() function is called on a matching entity in the same process
automatically, when it is no longer referenced by any entities in memory. For example, if the lock is put only on one local reference of an entity, the entity is unlocked when the function ends. As long as there are references to the entity in memory, the record remains locked.

By default, if the mode parameter is omitted, the function will return an error (see below) if the same entity was modified (i.e. the stamp has changed) by another process or user in the meantime.

Otherwise, you can pass the dk reload if stamp changed option in the mode parameter: in this case, no error is returned and the entity is reloaded when the stamp has changed (if the entity still exists and the primary key is still the same).

Result

The object returned by .lock( ) contains the following properties:

Property		Type	Description
success		boolean	true if the lock action is successful (or if the entity is already locked in the current process), false otherwise.
			Available only if `dk reload if stamp changed` option is used:
wasReloaded		boolean	true if the entity was reloaded with success, false otherwise.
			Available only in case of error:
status(*)		number	Error code, see below
statusText(*)		text	Description of the error, see below
			Available only in case of pessimistic lock error:
lockKindText		text	"Locked by record"
lockInfo		object	Information about the lock origin
	task_id	number	Process ID
	user_name	text	Session user name on the machine
	user4d_alias	text	Name or alias of the 4D user
	user4d_id	number	User id in the 4D database directory
	host_name	text	Machine name
	task_name	text	Process name
	client_version	text
			Available only in case of serious error (primary key already exists, disk full...):
errors		collection of objects
	message	text	Error message
	component signature	text	internal component signature (e.g. "dmbg" stands for the database component)
	errCode	number	Error code

(*) The following values can be returned in the status and statusText properties of the Result object in case of error:

Constant	Value	Comment
`dk status entity does not exist anymore`	5	The entity no longer exists in the data. This error can occur in the following cases: the entity has been dropped (the stamp has changed and the memory space is now free) the entity has been dropped and replaced by another one with another primary key (the stamp has changed and a new entity now uses the memory space). When using `.drop( )`, this error can be returned when dk force drop if stamp changed option is used. When using `.lock( )`, this error can be returned when `dk reload if stamp changed` option is used Associated statusText: "Entity does not exist anymore"
`dk status locked`	3	The entity is locked by a pessimistic lock.Associated statusText: "Already locked"
`dk status serious error`	4	A serious error is a low-level database error (e.g. duplicated key), a hardware error, etc.Associated statusText: "Other error"
`dk status stamp has changed`	2	The internal stamp value of the entity does not match the one of the entity stored in the data (optimistic lock). with `.save( )`: error only if the `dk auto merge` option is not used with `.drop( )`: error only if the `dk force drop if stamp changed` option is not used with `.lock( )`: error only if the `dk reload if stamp changed` option is not used Associated statusText: "Stamp has changed"

Example 1

Example with error:

 var $employee : cs.EmployeeEntity
 var $status : Object
 $employee:=ds.Employee.get(716)
 $status:=$employee.lock()
 Case of
    :($status.success)
       ALERT("You have locked "+$employee.firstName+" "+$employee.lastName)
    :($status.status=dk status stamp has changed)
       ALERT($status.statusText)
 End case

Example 2

Example with dk reload if stamp changed option:

 var $employee : cs.EmployeeEntity
 var $status : Object
 $employee:=ds.Employee.get(717)
 $status:=$employee.lock(dk reload if stamp changed)
 Case of
    :($status.success)
       ALERT("You have locked "+$employee.firstName+" "+$employee.lastName)
    :($status.status=dk status entity does not exist anymore)
       ALERT($status.statusText)
 End case

.next()

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.next() : 4D.Entity

Parameter	Type		Description
Result	4D.Entity	<-	Reference to next entity in the entity selection (Null if not found)

Description

The .next() function returns a reference to the next entity in the entity selection which the entity belongs to.

If the entity does not belong to any existing entity selection (i.e. .getSelection() returns Null), the function returns a Null value.

If there is no valid next entity in the entity selection (i.e. you are on the last entity of the selection), the function returns Null. If the next entity has been dropped, the function returns the next valid entity (and eventually Null).

Example

 var $employees : cs.EmployeeSelection
 var $employee; $nextEmployee : cs.EmployeeEntity
 $employees:=ds.Employee.query("lastName = :1";"H@") //This entity selection contains 3 entities
 $employee:=$employees[0]
 $nextEmployee:=$employee.next() //$nextEmployee is the second entity of the $employees entity selection

.previous()

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.previous() : 4D.Entity

Parameter	Type		Description
Result	4D.Entity	<-	Reference to previous entity in the entity selection (Null if not found)

Description

The .previous() function returns a reference to the previous entity in the entity selection which the entity belongs to.

If the entity does not belong to any existing entity selection (i.e. .getSelection() returns Null), the function returns a Null value.

If there is no valid previous entity in the entity selection (i.e. you are on the first entity of the selection), the function returns Null. If the previous entity has been dropped, the function returns the previous valid entity (and eventually Null).

Example

 var $employees : cs.EmployeeSelection
 var $employee; $previousEmployee : cs.EmployeeEntity
 $employees:=ds.Employee.query("lastName = :1";"H@") //This entity selection contains 3 entities
 $employee:=$employees[1]
 $previousEmployee:=$employee.previous() //$previousEmployee is the first entity of the $employees entity selection

.reload()

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.reload() : Object

Parameter	Type		Description
Result	Object	<-	Status object

Description

The .reload() function reloads the content of the entity in memory, according to information stored in the table related to the dataclass in the datastore. The reload is done only if the entity still exists with the same primary key.

Result

The object returned by .reload( ) contains the following properties:

Property	Type	Description
success	boolean	True if the reload action is successful, False otherwise.Available only in case of error:
status(*)	number	Error code, see below
statusText(*)	text	Description of the error, see below

(*) The following values can be returned in the status and statusText properties of Result object in case of error:

Constant	Value	Comment
`dk status entity does not exist anymore`	5	The entity no longer exists in the data. This error can occur in the following cases: the entity has been dropped (the stamp has changed and the memory space is now free) the entity has been dropped and replaced by another one with another primary key (the stamp has changed and a new entity now uses the memory space). When using `.drop( )`, this error can be returned when `dk force drop if stamp changed` option is used. When using `.lock( )`, this error can be returned when `dk reload if stamp changed` option is used Associated statusText: "Entity does not exist anymore"
`dk status serious error`	4	A serious error is a low-level database error (e.g. duplicated key), a hardware error, etc. Associated statusText: "Other error"

Example

 var $employee : cs.EmployeeEntity
 var $employees : cs.EmployeeSelection
 var $result : Object

 $employees:=ds.Employee.query("lastName=:1";"Hollis")
 $employee:=$employees[0]
 $employee.firstName:="Mary"
 $result:=$employee.reload()
 Case of
    :($result.success)
       ALERT("Reload has been done")
    :($result.status=dk status entity does not exist anymore)
       ALERT("The entity has been dropped")
 End case

.save()

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.save( { mode : Integer } ) : Object

Parameter	Type		Description
mode	Integer	->	`dk auto merge`: Enables the automatic merge mode
Result	Object	<-	Result of save operation

Description

The .save() function saves the changes made to the entity in the table related to its dataClass. You must call this method after creating or modifying an entity if you want to save the changes made to it.

The save operation is executed only if at least one entity attribute has been "touched" (see the .touched() and .touchedAttributes() functions). Otherwise, the function does nothing (the trigger is not called).

In a multi-user or multi-process application, the .save() function is executed under an "optimistic lock" mechanism, wherein an internal locking stamp is automatically incremented each time the record is saved.

By default, if the mode parameter is omitted, the method will return an error (see below) whenever the same entity has been modified by another process or user in the meantime, no matter the modified attribute(s).

Otherwise, you can pass the dk auto merge option in the mode parameter: when the automatic merge mode is enabled, a modification done concurrently by another process/user on the same entity but on a different attribute will not result in an error. The resulting data saved in the entity will be the combination (the "merge") of all non-concurrent modifications (if modifications were applied to the same attribute, the save fails and an error is returned, even with the auto merge mode).

The automatic merge mode is not available for attributes of Picture, Object, and Text type when stored outside of the record. Concurrent changes in these attributes will result in a dk status stamp has changed error.

Result

The object returned by .save() contains the following properties:

Property		Type	Description
success		boolean	True if the save action is successful, False otherwise.
			Available only if `dk auto merge` option is used:
autoMerged		boolean	True if an auto merge was done, False otherwise.
			Available only in case of error:
status		number	Error code, see below
statusText		text	Description of the error, see below
			Available only in case of pessimistic lock error:
lockKindText		text	"Locked by record"
lockInfo		object	Information about the lock origin
	task_id	number	Process id
	user_name	text	Session user name on the machine
	user4d_alias	text	User alias if defined by `SET USER ALIAS`, otherwise user name in the 4D directory
	host_name	text	Machine name
	task_name	text	Process name
	client_version	text
			Available only in case of serious error (serious error - can be trying to duplicate a primary key, disk full...):
errors		collection of objects
	message	text	Error message
	componentSignature	text	Internal component signature (e.g. "dmbg" stands for the database component)
	errCode	number	Error code

status and statusText

The following values can be returned in the status and statusText properties of Result object in case of error:

Constant	Value	Comment
`dk status automerge failed`	6	(Only if the `dk auto merge` option is used) The automatic merge option failed when saving the entity.Associated statusText: "Auto merge failed"
`dk status entity does not exist anymore`	5	The entity no longer exists in the data. This error can occur in the following cases: the entity has been dropped (the stamp has changed and the memory space is now free) the entity has been dropped and replaced by another one with another primary key (the stamp has changed and a new entity now uses the memory space). When using `.drop( )`, this error can be returned when `dk force drop if stamp changed` option is used. When using `.lock( )`, this error can be returned when `dk reload if stamp changed` option is used Associated statusText: "Entity doesnot exist anymore"
`dk status locked`	3	The entity is locked by a pessimistic lock.Associated statusText: "Already locked"
`dk status serious error`	4	A serious error is a low-level database error (e.g. duplicated key), a hardware error, etc.Associated statusText: "Other error"
`dk status stamp has changed`	2	The internal stamp value of the entity does not match the one of the entity stored in the data (optimistic lock). with `.save( )`: error only if the `dk auto merge` option is not used with `.drop( )`: error only if the `dk force drop if stamp changed` option is not used with `.lock( )`: error only if the `dk reload if stamp changed` option is not used Associated statusText: "Stamp has changed"

Example 1

Creating a new entity:

 var $status : Object
 var $employee : cs.EmployeeEntity
 $employee:=ds.Employee.new()
 $employee.firstName:="Mary"
 $employee.lastName:="Smith"
 $status:=$employee.save()
 If($status.success)
    ALERT("Employee created")
 End if

Example 2

Updating an entity without dk auto merge option:

 var $status : Object
 var $employee : cs.EmployeeEntity
 var $employees : cs.EmployeeSelection
 $employees:=ds.Employee.query("lastName=:1";"Smith")
 $employee:=$employees.first()
 $employee.lastName:="Mac Arthur"
 $status:=$employee.save()
 Case of
    :($status.success)
       ALERT("Employee updated")
    :($status.status=dk status stamp has changed)
       ALERT($status.statusText)
 End case

Example 3

Updating an entity with dk auto merge option:

 var $status : Object

 var $employee : cs.EmployeeEntity
 var $employees : cs.EmployeeSelection

 $employees:=ds.Employee.query("lastName=:1";"Smith")
 $employee:=$employees.first()
 $employee.lastName:="Mac Arthur"
 $status:=$employee.save(dk auto merge)
 Case of
    :($status.success)
       ALERT("Employee updated")
    :($status.status=dk status automerge failed)
       ALERT($status.statusText)
 End case

.toObject()

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.toObject() : Object
.toObject( filterString : Text { ; options : Integer} ) : Object
.toObject( filterCol : Collection { ; options : Integer } ) : Object

Parameter	Type		Description
filterString	Text	->	Attribute(s) to extract (comma-separated string)
filterCol	Collection	->	Collection of attribute(s) to extract
options	Integer	->	`dk with primary key`: adds the _KEY property; `dk with stamp`: adds the _STAMP property
Result	Object	<-	Object built from the entity

Description

The .toObject() function returns an object which has been built from the entity. Property names in the object match attribute names of the entity.

If no filter is specified, or if the filterString parameter contains an empty string or "*", the returned object will contain:

all storage entity attributes
attributes of the relatedEntity kind: you get a property with the same name as the related entity (name of the many-to-one link). Attribute is extracted with the simple form.
attributes of the relatedEntities kind: attribute is not returned.

In the first parameter, you pass the entity attribute(s) to extract. You can pass:

filterString: a string with property paths separated with commas: "propertyPath1, propertyPath2, ...", or
filterCol: a collection of strings: ["propertyPath1","propertyPath2";...]

If a filter is specified for attributes of the relatedEntity kind:

propertyPath = "relatedEntity" -> it is extracted with simple form: an object with property __KEY (primary key).
propertyPath = "relatedEntity.*" -> all the properties are extracted
propertyPath = "relatedEntity.propertyName1; relatedEntity.propertyName2; ..." -> only those properties are extracted

If a filter is specified for attributes of the relatedEntities kind:

propertyPath = "relatedEntities.*" -> all the properties are extracted
propertyPath = "relatedEntities.propertyName1; relatedEntities.propertyName2; ..." -> only those properties are extracted

In the options parameter, you can pass the dk with primary key and/ordk with stamp selector(s) to add the entity's primary keys and/or stamps in extracted objects.

Example 1

The following structure will be used throughout all examples of this section:

Without filter parameter:

employeeObject:=employeeSelected.toObject()

Returns:

{
    "ID": 413,
    "firstName": "Greg",
    "lastName": "Wahl",
    "salary": 0,
    "birthDate": "1963-02-01T00:00:00.000Z",
    "woman": false,
    "managerID": 412,
    "employerID": 20,
    "photo": "[object Picture]",
    "extra": null,
    "employer": { // relatedEntity extracted with simple form
        "__KEY": 20
    },
    "manager": {
        "__KEY": 412
    }
}

Example 2

Extracting the primary key and the stamp:

employeeObject:=employeeSelected.toObject("";dk with primary key+dk with stamp)

Returns:

{
    "__KEY": 413,
   "__STAMP": 1,
    "ID": 413,
    "firstName": "Greg",
    "lastName": "Wahl",
    "salary": 0,
    "birthDate": "1963-02-01T00:00:00.000Z",
    "woman": false,
    "managerID": 412,
    "employerID": 20,
    "photo": "[object Picture]",
    "extra": null,
    "employer": {
        "__KEY": 20
    },
    "manager": {
        "__KEY": 412
    }
}

Example 3

Expanding all the properties of relatedEntities:

employeeObject:=employeeSelected.toObject("directReports.*")

{
    "directReports": [
        {
            "ID": 418,
            "firstName": "Lorena",
            "lastName": "Boothe",
            "salary": 44800,
            "birthDate": "1970-10-02T00:00:00.000Z",
            "woman": true,
            "managerID": 413,
            "employerID": 20,
            "photo": "[object Picture]",
            "extra": null,
            "employer": {
                "__KEY": 20
            },
            "manager": {
                "__KEY": 413
            }
        },
        {
            "ID": 419,
            "firstName": "Drew",
            "lastName": "Caudill",
            "salary": 41000,
            "birthDate": "2030-01-12T00:00:00.000Z",
            "woman": false,
            "managerID": 413,
            "employerID": 20,
            "photo": "[object Picture]",
            "extra": null,
            "employer": {
                "__KEY": 20
            },
            "manager": {
                "__KEY": 413
            }
        },
        {
            "ID": 420,
            "firstName": "Nathan",
            "lastName": "Gomes",
            "salary": 46300,
            "birthDate": "2010-05-29T00:00:00.000Z",
            "woman": false,
            "managerID": 413,
            "employerID": 20,
            "photo": "[object Picture]",
            "extra": null,
            "employer": {
                "__KEY": 20
            },
            "manager": {
                "__KEY": 413
            }
        }
    ]
}

Example 4

Extracting some properties of relatedEntities:

 employeeObject:=employeeSelected.toObject("firstName, directReports.lastName")

Returns:

{
    "firstName": "Greg",
    "directReports": [
        {
            "lastName": "Boothe"
        },
        {
            "lastName": "Caudill"
        },
        {
            "lastName": "Gomes"
        }
    ]
}

Example 5

Extracting a relatedEntity with simple form:

 $coll:=New collection("firstName";"employer")
 employeeObject:=employeeSelected.toObject($coll)

Returns:

{
    "firstName": "Greg",
    "employer": {
        "__KEY": 20
    }
}

Example 6

Extracting all the properties of a relatedEntity:

 employeeObject:=employeeSelected.toObject("employer.*")

Returns:

{
    "employer": {
        "ID": 20,
        "name": "India Astral Secretary",
        "creationDate": "1984-08-25T00:00:00.000Z",
        "revenues": 12000000,
        "extra": null
    }
}

Example 7

Extracting some properties of a relatedEntity:

 $col:=New collection
 $col.push("employer.name")
 $col.push("employer.revenues")
 employeeObject:=employeeSelected.toObject($col)

Returns:

{
    "employer": {
        "name": "India Astral Secretary",
        "revenues": 12000000
    }
}

.touched( )

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.touched() : Boolean

Parameter	Type		Description
Result	Boolean	<-	True if at least one entity attribute has been modified and not yet saved, else False

Description

The .touched() function tests whether or not an entity attribute has been modified since the entity was loaded into memory or saved.

If an attribute has been modified or calculated, the function returns True, else it returns False. You can use this function to determine if you need to save the entity.

This function returns False for a new entity that has just been created (with .new( )). Note however that if you use a function which calculates an attribute of the entity, the .touched() function will then return True. For example, if you call .getKey() to calculate the primary key, .touched() returns True.

Example

In this example, we check to see if it is necessary to save the entity:

 var $emp : cs.EmployeeEntity
 $emp:=ds.Employee.get(672)
 $emp.firstName:=$emp.firstName //Even if updated with the same value, the attribute is marked as touched

 If($emp.touched()) //if at least one of the attributes has been changed
    $emp.save()
 End if // otherwise, no need to save the entity

.touchedAttributes( )

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.touchedAttributes() : Collection

Parameter	Type		Description
Result	Collection	<-	Names of touched attributes, or empty collection

Description

The .touchedAttributes() function returns the names of the attributes that have been modified since the entity was loaded into memory.

This applies for attributes of the kind storage or relatedEntity.

In the case of a related entity having been touched (i.e., the foreign key), the name of the related entity and its primary key's name are returned.

If no entity attribute has been touched, the method returns an empty collection.

Example 1

 var $touchedAttributes : Collection
 var $emp : cs.EmployeeEntity

 $touchedAttributes:=New collection
 $emp:=ds.Employee.get(725)
 $emp.firstName:=$emp.firstName //Even if updated with the same value, the attribute is marked as touched
 $emp.lastName:="Martin"
 $touchedAttributes:=$emp.touchedAttributes()
  //$touchedAttributes: ["firstName","lastName"]

Example 2

 var $touchedAttributes : Collection
 var $emp : cs.EmployeeEntity
 var $company : cs.CompanyEntity

 $touchedAttributes:=New collection

 $emp:=ds.Employee.get(672)
 $emp.firstName:=$emp.firstName
 $emp.lastName:="Martin"

 $company:=ds.Company.get(121)
 $emp.employer:=$company

 $touchedAttributes:=$emp.touchedAttributes()

  //collection $touchedAttributes: ["firstName","lastName","employer","employerID"]

In this case:

firstName and lastName have a storage kind
employer has a relatedEntity kind
employerID is the foreign key of the employer related entity

.unlock()

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.unlock() : Object

Parameter	Type		Description
Result	Object	<-	Status object

Description

The .unlock() function removes the pessimistic lock on the record matching the entity in the datastore and table related to its dataclass.

For more information, please refer to Entity locking section.

A record is automatically unlocked when it is no longer referenced by any entities in the locking process (for example: if the lock is put only on one local reference of an entity, the entity and thus the record is unlocked when the process ends).

When a record is locked, it must be unlocked from the locking process and on the entity reference which put the lock. For example:

 $e1:=ds.Emp.all()[0]
 $e2:=ds.Emp.all()[0]
 $res:=$e1.lock() //$res.success=true
 $res:=$e2.unlock() //$res.success=false
 $res:=$e1.unlock() //$res.success=true

Result

The object returned by .unlock() contains the following property:

Property	Type	Description
success	Boolean	True if the unlock action is successful, False otherwise. If the unlock is done on a dropped entity, on a non locked record, or on a record locked by another process or entity, success is False.

Example

 var $employee : cs.EmployeeEntity
 var $status : Object

 $employee:=ds.Employee.get(725)
 $status:=$employee.lock()
 ... //processing
 $status:=$employee.unlock()
 If($status.success)
    ALERT("The entity is now unlocked")
 End if

Summary​

.attributeName​

Description​

Example​

.clone()​

Description​

Example​

.diff()​

Description​

Example 1​

Example 2​

.drop()​

Description​

Example 1​

Example 2​

.first()​

Description​

Example​

.fromObject()​

Description​

Example​

.getDataClass()​

Description​

Example​

.getKey()​

Description​

Example​

.getSelection()​

Description​

Example​

.getStamp()​

Description​

Example​

.indexOf()​

Description​

Example​

.isNew()​

Description​

Example​

.last()​

Description​

Example​

.lock()​

Description​

Example 1​

Example 2​

.next()​

Description​

Example​

.previous()​

Description​

Example​

.reload()​

Description​

Example​

.save()​

Description​

status and statusText​

Example 1​

Example 2​

Example 3​

.toObject()​

Description​

Example 1​

Example 2​

Example 3​

Example 4​

Example 5​

Example 6​

Example 7​

.touched( )​

Description​

Example​

.touchedAttributes( )​

Description​

Example 1​

Example 2​

.unlock()​

Description​

Example​

Summary

.attributeName

Description

Example

.clone()

Description

Example

.diff()

Description

Example 1

Example 2

.drop()

Description

Example 1

Example 2

.first()

Description

Example

.fromObject()

Description

Example

.getDataClass()

Description

Example

.getKey()

Description

Example

.getSelection()

Description

Example

.getStamp()

Description

Example

.indexOf()

Description

Example

.isNew()

Description

Example

.last()

Description

Example

.lock()

Description

Example 1

Example 2

.next()

Description

Example

.previous()

Description

Example

.reload()

Description

Example

.save()

Description

status and statusText

Example 1

Example 2

Example 3

.toObject()

Description

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

Example 7

.touched( )

Description

Example

.touchedAttributes( )

Description

Example 1

Example 2

.unlock()

Description

Example