Delete Objects from relation

The API removes specific objects from a relationship with their parent.

Using Untyped ObjectsCustom Class/Function

Backendless.Data.of("TABLE-NAME").deleteRelation(parent, relationColumnName, childrenArray): Promise<string>;

Backendless.Data.of(DataTypeX).deleteRelation(parent, relationColumnName, childrenArray): Promise<string>;

where:

Argument	Description
TABLE-NAME	Name of the table where the parent object is stored.
DataTypeX	Reference to a JS function/class identifying the table. Name of the table must match the name of the function.
parent	The object for which the relation with the specified children will be deleted. This property expects the objectId value of the string or number type. When this argument is a plain JS object(for the "Untyped Objects" approach), it must contain the "objectId" property whose value must be a string or a number. Refer to the Data Import topic to learn more about the objectId value as the number.
relationColumnName	name of the column identifying the relation. Relation between the parent object and the objects from the childrenArray array for the  column in parentObject will be deleted.
childrenArray	An array of child objects for which the relation with parentObject will be deleted.

Return Value

Number of child objects for which the relationship has been deleted.

Example

The example below deletes a relation between an object from the Person table and its children. The child objects are referenced explicitly in the API call (see the object IDs in the collection as "XXXXX-XXXXX-XXXXX-XXXXX" and "ZZZZ-ZZZZ-ZZZZZ-ZZZZZ"``).The relation column is address.

Using Untyped ObjectsCustom Class/Function

var parentObject = { objectId:"41230622-DC4D-204F-FF5A-F893A0324800"};
var childObject1 = { objectId:"XXXX-XXXX-XXXX-XXXXX" };
var childObject2 = { objectId:"ZZZZ-ZZZZ-ZZZZZ-ZZZZZ" };
var children = [ childObject1, childObject2 ];

Backendless.Data.of( "Person" ).deleteRelation( parentObject, "address", children )
 .then( function( count ) {
    console.log( "relation has been deleted" );
  })
 .catch( function( error ) {
    console.log( "server reported an error - " + error.message );
  });

function Person {
  // properties of Person defined here
}

function Address {
  // properties of Address defined here
}

var personObject = // personObject retrieval is out of scope in this example
var addressObject1 = // addressObject retrieval is out of scope in this example
var addressObject2 = // addressObject retrieval is out of scope in this example
var addressCollection = [ addressObject1, addressObject2 ];

Backendless.Data.of( Person ).deleteRelation( personObject, "address", addressCollection )
  .then( function( count ) {
     console.log( "relation has been deleted");
   })
  .catch( function( error ) {
     console.log( "server reported an error - " + error.message );
   });

Codeless Reference

where:

Argument	Description
table name	Name of the table where which contains the parent object as identified by parent object.
parent object	Id of the object for which the relation will be deleted.
relation name	Name of the column which identifies the relation within the parent table (identified as table name).
children	Represents a list containing unique identifiers(objectIds) of the children objects relations that must be deleted from the data table.
return result	When this box is checked, the operation returns the number of removed child objects relations.

Returns the number of removed child objects relations.

Consider the first object with one-to-many relations(skills column) in the parent data table called employees:

By clicking the record (1:N Relations) in the skills column of the parent data table presented above, you get redirected to the child data table called uniqueSkills, where you can see the related children objects:

Suppose you want to remove two relations. The following example demonstrates the removal of the Objective-C and Javascript relations from the parent object:

The objectId values for each relation are:

1. Objective-C: "4E205196-59B0-45A6-BACB-303A66BEFF22"

2. Javascript: "D08FA6A7-4534-4B43-AF06-BC4CBFE54C60"

After the operation runs, the Objective-C and Javascript relations get deleted.