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

Returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.

Syntax

Visual Basic
C#

'Declaration
 
<ExtensionAttribute()>
Public Overloads Shared Function SingleOrDefault( _
   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.SingleOrDefault(source, predicateDescription, userCallback, userState)

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

Parameters

source
predicateDescription
userCallback
userState

Example

public void AsyncSingleOrDefaultWithPredicate() {
   var op = _entityManager.Employees.AsScalarAsync().SingleOrDefault(e => e.Id == 1);
   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