EntityFrameworkQueryableExtensions.FirstAsync Method

Definition

Namespace:

Microsoft.EntityFrameworkCore

Assembly:

Microsoft.EntityFrameworkCore.dll

Package:

Microsoft.EntityFrameworkCore v8.0.0

Overloads

FirstAsync<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>, CancellationToken)	Asynchronously returns the first element of a sequence that satisfies a specified condition.
FirstAsync<TSource>(IQueryable<TSource>, CancellationToken)	Asynchronously returns the first element of a sequence.

FirstAsync<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>, CancellationToken)

Asynchronously returns the first element of a sequence that satisfies a specified condition.

public static System.Threading.Tasks.Task<TSource> FirstAsync<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,bool>> predicate, System.Threading.CancellationToken cancellationToken = default);

static member FirstAsync : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, bool>> * System.Threading.CancellationToken -> System.Threading.Tasks.Task<'Source>

<Extension()>
Public Function FirstAsync(Of TSource) (source As IQueryable(Of TSource), predicate As Expression(Of Func(Of TSource, Boolean)), Optional cancellationToken As CancellationToken = Nothing) As Task(Of TSource)

Type Parameters

TSource

The type of the elements of source.

Parameters

source

IQueryable<TSource>

An IQueryable<T> to return the first element of.

predicate

Expression<Func<TSource,Boolean>>

A function to test each element for a condition.

cancellationToken

CancellationToken

A CancellationToken to observe while waiting for the task to complete.

Returns

Task<TSource>

A task that represents the asynchronous operation. The task result contains the first element in source that passes the test in predicate.

Exceptions

ArgumentNullException

source or predicate is null.

InvalidOperationException

No element satisfies the condition in predicate

-or -

source contains no elements.

OperationCanceledException

If the CancellationToken is canceled.

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 Avoiding DbContext threading issues for more information and examples.

See Querying data with EF Core for more information and examples.

FirstAsync<TSource>(IQueryable<TSource>, CancellationToken)

Asynchronously returns the first element of a sequence.

public static System.Threading.Tasks.Task<TSource> FirstAsync<TSource> (this System.Linq.IQueryable<TSource> source, System.Threading.CancellationToken cancellationToken = default);

static member FirstAsync : System.Linq.IQueryable<'Source> * System.Threading.CancellationToken -> System.Threading.Tasks.Task<'Source>

<Extension()>
Public Function FirstAsync(Of TSource) (source As IQueryable(Of TSource), Optional cancellationToken As CancellationToken = Nothing) As Task(Of TSource)

Type Parameters

TSource

The type of the elements of source.

Parameters

source

IQueryable<TSource>

An IQueryable<T> to return the first element of.

cancellationToken

CancellationToken

A CancellationToken to observe while waiting for the task to complete.

Returns

Task<TSource>

A task that represents the asynchronous operation. The task result contains the first element in source.

Exceptions

ArgumentNullException

source is null.

InvalidOperationException

source contains no elements.

OperationCanceledException

If the CancellationToken is canceled.

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 Avoiding DbContext threading issues for more information and examples.

See Querying data with EF Core for more information and examples.