entitySelection.first( )

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4D v18

Description

The entitySelection.first( ) method returns a reference to the entity in the first position of the entity selection.

The result of this method is similar to:

$entity:=$entitySel[0]

There is, however, a difference between both statements when the selection is empty:

 C_OBJECT($entitySel;$entity)

 $entitySel:=ds.Emp.query("lastName = :1";"Nonexistentname") //no matching entity

  //entity selection is then empty

 $entity:=$entitySel.first() //returns Null

 $entity:=$entitySel[0]  //generates an error

Example

 C_OBJECT($entitySelection;$entity)

 $entitySelection:=ds.Emp.query("salary > :1";100000)

 If($entitySelection.length#0)

    $entity:=$entitySelection.first()

 End if