FirstOrNullEntity(IEntityScalarQuery,IPredicateDescription,Action<EntityScalarQueryOperation>,Object) Method

Returns the first element of a sequence that satisfies a specified condition, or the appropriate NullEntity if no such element is found.

Syntax

Visual Basic
C#

'Declaration
 
<ExtensionAttribute()>
Public Overloads Shared Function FirstOrNullEntity( _
   ByVal source As IEntityScalarQuery, _
   ByVal predicateDescription As IPredicateDescription, _
   ByVal userCallback As Action(Of EntityScalarQueryOperation), _
   Optional ByVal userState As Object _
) As EntityScalarQueryOperation

'Usage
 
Dim source As IEntityScalarQuery
Dim predicateDescription As IPredicateDescription
Dim userCallback As Action(Of EntityScalarQueryOperation)
Dim userState As Object
Dim value As EntityScalarQueryOperation
 
value = EntityScalarQueryAsyncExtensions.FirstOrNullEntity(source, predicateDescription, userCallback, userState)

[Extension()]
public static EntityScalarQueryOperation FirstOrNullEntity( 
   IEntityScalarQuery source,
   IPredicateDescription predicateDescription,
   Action<EntityScalarQueryOperation> userCallback,
   object userState
)

Parameters

source
predicateDescription
userCallback
userState

Example

public void AsyncFirstOrNullEntityWithPredicate() {
  var op = _entityManager.Employees.AsScalarAsync().FirstOrNullEntity(e => e.LastName.StartsWith("D"));
  op.Completed += (o, e) => {
    var emp = e.Result;
  };
}

Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

EntityScalarQueryAsyncExtensions Class
EntityScalarQueryAsyncExtensions Members
Overload List