SingleOrDefault(IEntityScalarQuery,IPredicateDescription,CancellationToken) 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. Pass in a System.Threading.CancellationToken to cancel operation.

Syntax

Visual Basic
C#

'Declaration
 
<ExtensionAttribute()>
Public Overloads Shared Function SingleOrDefault( _
   ByVal source As IEntityScalarQuery, _
   ByVal predicateDescription As IPredicateDescription, _
   ByVal cancellationToken As CancellationToken _
) As Task

'Usage
 
Dim source As IEntityScalarQuery
Dim predicateDescription As IPredicateDescription
Dim cancellationToken As CancellationToken
Dim value As Task
 
value = EntityScalarAsyncExtensions.SingleOrDefault(source, predicateDescription, cancellationToken)

[Extension()]
public static Task SingleOrDefault( 
   IEntityScalarQuery source,
   IPredicateDescription predicateDescription,
   CancellationToken cancellationToken
)

Parameters

source
predicateDescription
cancellationToken

Example

public async void AsyncSingleOrDefaultWithPredicate() {
   Employee emp = await _entityManager.Employees.AsScalarAsync().SingleOrDefault(e => e.Id == 1);
 }

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

EntityScalarAsyncExtensions Class
EntityScalarAsyncExtensions Members
Overload List