Add Relation using condition¶
This API request adds related objects to the existing collection. Child objects to add to the relation are defined through a whereClause condition.
Backendless.Data.of( "TABLE-NAME" ).addRelation(
parentObject,
relationColumnName,
whereClause )
.then( function( count ) {
})
.catch( function( error ) {
});
Backendless.Data.of( DataTypeX ).addRelation(
parentObject,
relationColumnName,
whereClause )
.then( function( count ) {
})
.catch( function( error ) {
});
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. |
parentObject |
The object which will receive related children for relatedColumnName . When this argument is a plain JS object(for the "Untyped Objects" approach), it must contain the "objectId" property. |
relationColumnName |
Name of the column identifying the relation. Objects identified by the whereClause argument will be added as related objects for the column in parentObject . The column name may optionally include table name separated by the colon character (see the note below): |
Important
If the column does not exist in the parent table at the time when the API is called, the value of the "relationColumnName
" argument must include the name of the child table separated by colon and the cardinality notation. The cardinality is expressed as ":1
" for one-to-one relations and ":n
" for one-to-many relations. For example, the value of "myOrder:Order:1
" will create a one-to-one relation column "myOrder
" in the parent table. The column will point to the Order
child table. Likewise, the value of "myOrder:Order:n
" will create a one-to-many relation column "myOrder
" pointing to the Order
table.
Argument | Description |
---|---|
whereClause |
A where clause condition identifying objects in the child table which will be added as related objects to the parent object. |
Return Value¶
Number of child objects added to the relation.
Example¶
The following request adds objects from the Users
table to the related property/column the Person
object. Child objects added to the relation must match the provided query. The query is specified in the whereClause
argument:
name='Joe' or name = 'Frank'.
As a result of the operation, all User objects where the name
property is either Joe
or Frank
will be added to the relation. The relation column is created if it does not exist. This is done because the column name argument contains the child table qualifier, defined as ":Users:n"
right after the column name.
var parentObject { objectId:"41230622-DC4D-204F-FF5A-F893A0324800" };
Backendless.Data.of( "Person" ).addRelation( parentObject,
"users:Users:n",
"name = \"Joe\" or name = \"Frank\"" )
.then( function( count ) {
console.log( "related objects have been added" );
})
.catch( function( error ) {
console.log( "server reported an error - " + error.message );
});
Person personObject = // personObject retrieval is out of scope in this example
Backendless.Data.of( Person.class ).addRelation( personObject,
"users:Users:n",
"name = \"Joe\" or name = \"Frank\"",
new AsyncCallback<Integer>()
{
@Override
public void handleResponse( Integer response )
{
Log.i( "MYAPP", "related objects have been added");
}
@Override
public void handleFault( BackendlessFault fault )
{
Log.e( "MYAPP", "server reported an error - " + fault.getMessage() );
}
} );