QueryableExtensions.CountAsync<TSource> Method (IQueryable<TSource>, Expression<Func<TSource, Boolean>>, CancellationToken)

[This page is specific to the Entity Framework version 6. The latest version is available as the 'Entity Framework' NuGet package. For more information about Entity Framework, see msdn.com/data/ef.]

Asynchronously returns the number of elements in a sequence that satisfy a condition.

Namespace:  System.Data.Entity
Assembly:  EntityFramework (in EntityFramework.dll)

Syntax

'Declaration
<SuppressMessageAttribute("Microsoft.Design", "CA1011:ConsiderPassingBaseTypesAsParameters")> _
<SuppressMessageAttribute("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures")> _
<ExtensionAttribute> _
Public Shared Function CountAsync(Of TSource) ( _
    source As IQueryable(Of TSource), _
    predicate As Expression(Of Func(Of TSource, Boolean)), _
    cancellationToken As CancellationToken _
) As Task(Of Integer)
'Usage
Dim source As IQueryable(Of TSource)
Dim predicate As Expression(Of Func(Of TSource, Boolean))
Dim cancellationToken As CancellationToken 
Dim returnValue As Task(Of Integer)

returnValue = source.CountAsync(predicate, _
    cancellationToken)

[SuppressMessageAttribute("Microsoft.Design", "CA1011:ConsiderPassingBaseTypesAsParameters")]
[SuppressMessageAttribute("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures")]
public static Task<int> CountAsync<TSource>(
    this IQueryable<TSource> source,
    Expression<Func<TSource, bool>> predicate,
    CancellationToken cancellationToken
)

[SuppressMessageAttribute(L"Microsoft.Design", L"CA1011:ConsiderPassingBaseTypesAsParameters")]
[SuppressMessageAttribute(L"Microsoft.Design", L"CA1006:DoNotNestGenericTypesInMemberSignatures")]
[ExtensionAttribute]
public:
generic<typename TSource>
static Task<int>^ CountAsync(
    IQueryable<TSource>^ source, 
    Expression<Func<TSource, bool>^>^ predicate, 
    CancellationToken cancellationToken
)

[<SuppressMessageAttribute("Microsoft.Design", "CA1011:ConsiderPassingBaseTypesAsParameters")>]
[<SuppressMessageAttribute("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures")>]
static member CountAsync : 
        source:IQueryable<'TSource> * 
        predicate:Expression<Func<'TSource, bool>> * 
        cancellationToken:CancellationToken -> Task<int> 

JScript does not support generic types and methods.

Type Parameters

• TSource
  The type of the elements of source.

Parameters

• source
  Type: System.Linq.IQueryable<TSource>
  An IQueryable<T> that contains the elements to be counted.

• predicate
  Type: System.Linq.Expressions.Expression<Func<TSource, Boolean>>
  A function to test each element for a condition.

• cancellationToken
  Type: System.Threading.CancellationToken
  A CancellationToken to observe while waiting for the task to complete.

Return Value

Type: System.Threading.Tasks.Task<Int32>
A task that represents the asynchronous operation. The task result contains the number of elements in the sequence that satisfy the condition in the predicate function.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable<TSource>. When you use instance method syntax to call this method, omit the first parameter. For more information, see https://msdn.microsoft.com/en-us/library/bb384936(v=vs.113) or https://msdn.microsoft.com/en-us/library/bb383977(v=vs.113).

Exceptions

Remarks

Multiple active operations on the same context instance are not supported. Use 'await' to ensure that any asynchronous operations have completed before calling another method on this context.

See Also

Reference

QueryableExtensions Class

CountAsync Overload

System.Data.Entity Namespace