Calling ORDA class functions

You can call data model class functions defined for the ORDA Data Model through your REST requests, so that you can benefit from the exposed API of the targeted 4D application.

Functions are simply called in POST requests on the appropriate ORDA interface, without (). For example, if you have defined a getCity() function in the City dataclass class, you could call it using the following request:

/rest/City/getCity

with data in the body of the POST request: ["Aguada"]

In 4D language, this call is equivalent to, :

$city:=ds.City.getCity("Aguada")

Only functions with the exposed keyword can be directly called from REST requests. See Exposed vs non-exposed functions section.

Function calls

Functions must always be called using REST POST requests (a GET request will receive an error).

Functions are called on the corresponding object on the server datastore.

Class function	Syntax
datastore class	/rest/$catalog/DataStoreClassFunction
dataclass class	/rest/\{dataClass\}/DataClassClassFunction
entitySelection class	/rest/\{dataClass\}/EntitySelectionClassFunction
	/rest/\{dataClass\}/EntitySelectionClassFunction/$entityset/entitySetNumber
	/rest/\{dataClass\}/EntitySelectionClassFunction/$filter
	/rest/\{dataClass\}/EntitySelectionClassFunction/$orderby
entity class	/rest/\{dataClass\}(key)/EntityClassFunction/

/rest/\{dataClass\}/Function can be used to call either a dataclass or an entity selection function (/rest/\{dataClass\} returns all entities of the DataClass as an entity selection). The function is searched in the entity selection class first. If not found, it is searched in the dataclass. In other words, if a function with the same name is defined in both the DataClass class and the EntitySelection class, the dataclass class function will never be executed.

All 4D code called from REST requests must be thread-safe if the project runs in compiled mode, because the REST Server always uses preemptive processes in this case (the Use preemptive process setting value is ignored by the REST Server).

Parameters

You can send parameters to functions defined in ORDA user classes. On the server side, they will be received in the class functions in regular $1, $2, etc. parameters.

The following rules apply:

• Parameters must be passed in the body of the POST request
• Parameters must be enclosed within a collection (JSON format)
• All scalar data types supported in JSON collections can be passed as parameters.
• Entity and entity selection can be passed as parameters. The JSON object must contain specific attributes used by the REST server to assign data to the corresponding ORDA objects: __DATACLASS,__ENTITY, __ENTITIES,__DATASET.

See this example and this example.

Scalar value parameter

Parameter(s) must simply be enclosed in a collection defined in the body. For example, with a dataclass function getCities() receiving text parameters: /rest/City/getCities

Parameters in body: ["Aguada","Paris"]

All JSON data types are supported in parameters, including JSON pointers. Dates can be passed as strings in ISO 8601 date format (e.g. "2020-08-22T22:00:000Z").

Entity parameter

Entities passed in parameters are referenced on the server through their key (i.e. __KEY property). If the key parameter is omitted in a request, a new entity is loaded in memory the server. You can also pass values for any attributes of the entity. These values will automatically be used for the entity handled on the server.

If the request sends modified attribute values for an existing entity on the server, the called ORDA data model function will be automatically executed on the server with modified values. This feature allows you, for example, to check the result of an operation on an entity, after applying all business rules, from the client application. You can then decide to save or not the entity on the server.

Properties	Type	Description
Attributes of the entity	mixed	Optional - Values to modify
__DATACLASS	String	Mandatory - Indicates the Dataclass of the entity
__ENTITY	Boolean	Mandatory - True to indicate to the server that the parameter is an entity
__KEY	mixed (same type as the primary key)	Optional - Primary key of the entity

• If __KEY is not provided, a new entity is created on the server with the given attributes.
• If __KEY is provided, the entity corresponding to__KEY is loaded on the server with the given attributes

See examples for creating or updating entities.

Related entity parameter

Same properties as for an entity parameter. In addition, the related entity must exist and is referenced by __KEY containing its primary key.

See examples for creating or updating entities with related entities.

Entity selection parameter

The entity selection must have been defined beforehand using $method=entityset.

If the request sends a modified entity selection to the server, the called ORDA data model function will be automatically executed on the server with the modified entity selection.

Properties	Type	Description
Attributes of the entity	mixed	Optional - Values to modify
__DATASET	String	Mandatory - entitySetID (UUID) of the entity selection
__ENTITIES	Boolean	Mandatory - True to indicate to the server that the parameter is an entity selection

See example for receiving an entity selection.

Request examples

This database is exposed as a remote datastore on localhost (port 8111):

Using a datastore class function

The US_Cities DataStore class provides an API:

// DataStore class

Class extends DataStoreImplementation

exposed Function getName()
    $0:="US cities and zip codes manager" 

You can then run this request:

POST 127.0.0.1:8111/rest/$catalog/getName

Result

{
"result": "US cities and zip codes manager" 
}

Using a dataclass class function

The Dataclass class City provides an API that returns a city entity from a name passed in parameter:

// City class

Class extends DataClass

exposed Function getCity()
 var $0 : cs.CityEntity
 var $1,$nameParam : text
 $nameParam:=$1
 $0:=This.query("name = :1";$nameParam).first()

You can then run this request:

POST 127.0.0.1:8111/rest/City/getCity

Body of the request: ["Aguada"]

Result

The result is an entity:

{
    "__entityModel": "City",
    "__DATACLASS": "City",
    "__KEY": "1",
    "__TIMESTAMP": "2020-03-09T08:03:19.923Z",
    "__STAMP": 1,
    "ID": 1,
    "name": "Aguada",
    "countyFIPS": 72003,
    "county": {
        "__deferred": {
            "uri": "/rest/County(72003)",
            "__KEY": "72003" 
        }
    },
    "zips": {
        "__deferred": {
            "uri": "/rest/City(1)/zips?$expand=zips" 
        }
    }
}

Using an entity class function

The Entity class CityEntity provides an API:

// CityEntity class

Class extends Entity

exposed Function getPopulation()
    $0:=This.zips.sum("population")

You can then run this request:

POST 127.0.0.1:8111/rest/City(2)/getPopulation

Result

{
    "result": 48814
}

Using an entitySelection class function

The EntitySelection class CitySelection provides an API:

// CitySelection class

Class extends EntitySelection

exposed Function getPopulation()
    $0:=This.zips.sum("population")

You can then run this request:

POST 127.0.0.1:8111/rest/City/getPopulation/?$filter="ID<3"

Result

{
    "result": 87256
}

Using an entitySelection class function and an entitySet

The StudentsSelection class has a getAgeAverage function:

// StudentsSelection Class

Class extends EntitySelection

exposed Function getAgeAverage
 C_LONGINT($sum;$0)
 C_OBJECT($s)

 $sum:=0
 For each ($s;This)
     $sum:=$sum+$s.age()
 End for each 
 $0:=$sum/This.length

Once you have created an entityset, you can run this request:

POST 127.0.0.1:8044/rest/Students/getAgeAverage/$entityset/17E83633FFB54ECDBF947E5C620BB532

Result

{
    "result": 34
}

Using an entitySelection class function and an orderBy

The StudentsSelection class has a getLastSummary function:

// StudentsSelection Class


Class extends EntitySelection

exposed Function getLastSummary
 C_TEXT($0)
 C_OBJECT($last)

 $last:=This.last()
 $0:=$last.firstname+" - "+$last.lastname+" is ... "+String($last.age())

You can then run this request:

POST 127.0.0.1:8044/rest/Students/getLastSummary/$entityset/?$filter="lastname=b@"&$orderby="lastname"

Result

{
    "result": "Wilbert - Bull is ... 21" 
}

Using an entity to be created on the server

The Dataclass class Students has the function pushData() receiving an entity containing data from the client. The checkData() method runs some controls. If they are OK, the entity is saved and returned.

// Students Class

Class extends DataClass

exposed Function pushData
 var $1, $entity, $status, $0 : Object

 $entity:=$1

 $status:=checkData($entity) // $status is an object with a success boolean property

 $0:=$status

 If ($status.success)
     $status:=$entity.save()
     If ($status.success)
         $0:=$entity
     End if 
 End if

You run this request:

POST http://127.0.0.1:8044/rest/Students/pushData

Body of the request:

[{
"__DATACLASS":"Students",
"__ENTITY":true,
"firstname":"Ann",
"lastname":"Brown" 
}]

Since no __KEY is given, a new Students entity is loaded on the server with the attributes received from the client. Because the pushData() function runs a save() action, the new entity is created.

Result

{
    "__entityModel": "Students",
    "__DATACLASS": "Students",
    "__KEY": "55",
    "__TIMESTAMP": "2020-06-16T10:54:41.805Z",
    "__STAMP": 1,
    "ID": 55,
    "firstname": "Ann",
    "lastname": "BROWN",
    "schoolID": null,
    "school": null
}

Using an entity to be updated on the server

Same as above but with a __KEY attribute

You run this request:

POST:http://127.0.0.1:8044/rest/Students/pushData

Body of the request:

[{
"__DATACLASS":"Students",
"__ENTITY":true,
"lastname":"Brownie",
"__KEY":55
}]

Since __KEY is given, the Students entity with primary key 55 is loaded with the lastname value received from the client. Because the function runs a save() action, the entity is updated.

Result

{
    "__entityModel": "Students",
    "__DATACLASS": "Students",
    "__KEY": "55",
    "__TIMESTAMP": "2020-06-16T11:10:21.679Z",
    "__STAMP": 3,
    "ID": 55,
    "firstname": "Ann",
    "lastname": "BROWNIE",
    "schoolID": null,
    "school": null 
}

Creating an entity with a related entity

In this example, we create a new Students entity with the Schools entity having primary key 2.

You run this request:

POST:http://127.0.0.1:8044/rest/Students/pushData

Body of the request:

[{
"__DATACLASS":"Students",
"__ENTITY":true,
"firstname":"John",
"lastname":"Smith",
"school":{"__KEY":2}
}]

Result

{
    "__entityModel": "Students",
    "__DATACLASS": "Students",
    "__KEY": "56",
    "__TIMESTAMP": "2020-06-16T11:16:47.601Z",
    "__STAMP": 1,
    "ID": 56,
    "firstname": "John",
    "lastname": "SMITH",
    "schoolID": 2,
       "school": {
        "__deferred": {
            "uri": "/rest/Schools(2)",
            "__KEY": "2" 
        }
    }
}

Updating an entity with a related entity

In this example, we associate an existing school to a Students entity. The StudentsEntity class has an API:

// StudentsEntity class

Class extends Entity

exposed Function putToSchool()
 var $1, $school , $0, $status : Object

  //$1 is a Schools entity
 $school:=$1
  //Associate the related entity school to the current Students entity
 This.school:=$school

 $status:=This.save()

 $0:=$status

You run this request, called on a Students entity : POST http://127.0.0.1:8044/rest/Students(1)/putToSchool Body of the request:

[{
"__DATACLASS":"Schools",
"__ENTITY":true,
"__KEY":2
}]

Result

{
    "result": {
        "success": true
    }
}

Receiving an entity selection as parameter

In the Students Dataclass class, the setFinalExam() function updates a received entity selection ($1). It actually updates the finalExam attribute with the received value ($2). It returns the primary keys of the updated entities.

// Students class

Class extends DataClass

exposed Function setFinalExam()

    var $1, $es, $student, $status : Object
    var $2, $examResult : Text

    var $keys, $0 : Collection

      //Entity selection
    $es:=$1

    $examResult:=$2

    $keys:=New collection()

      //Loop on the entity selection
    For each ($student;$es)
        $student.finalExam:=$examResult
        $status:=$student.save()
        If ($status.success)
            $keys.push($student.ID)
        End if 
    End for each 

    $0:=$keys

An entity set is first created with this request:

http://127.0.0.1:8044/rest/Students/?$filter="ID<3"&$method=entityset

Then you can run this request:

POST http://127.0.0.1:8044/rest/Students/setFinalExam

Body of the request:

[
{
"__ENTITIES":true,
"__DATASET":"9B9C053A111E4A288E9C1E48965FE671" 
},
"Passed" 
]

Result

The entities with primary keys 1 and 2 have been updated.

{
    "result": [
        1,
        2
    ]
}

Using an entity selection updated on the client

Using the getAgeAverage() function defined above.

var $remoteDS, $newStudent, $students : Object
var $ageAverage : Integer

$remoteDS:=Open datastore(New object("hostname";"127.0.0.1:8044");"students")

// $newStudent is a student entity to procees
$newStudent:=...
$students:=$remoteDS.Students.query("school.name = :1";"Math school")
// We add an entity to the $students entity selection on the client
$students.add($newStudent) 

// We call a function on the StudentsSelection class returning the age average of the students in the entity selection
// The function is executed on the server on the updated $students entity selection which included the student added from the client
$ageAverage:=$students.getAgeAverage()