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QueryableExtensions.FirstAsync Method

Definition

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>)

Asynchronously returns the first element of a sequence.

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

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

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

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

[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1011:ConsiderPassingBaseTypesAsParameters")]
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures")]
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);
static member FirstAsync : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, bool>> * System.Threading.CancellationToken -> System.Threading.Tasks.Task<'Source>

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.

Attributes

Exceptions

source or predicate is null .

No element satisfies the condition in predicate .

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.

Applies to

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

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

source is null .

The source sequence is empty.

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.

Applies to

FirstAsync<TSource>(IQueryable<TSource>)

Asynchronously returns the first element of a sequence.

public static System.Threading.Tasks.Task<TSource> FirstAsync<TSource> (this System.Linq.IQueryable<TSource> source);
static member FirstAsync : System.Linq.IQueryable<'Source> -> System.Threading.Tasks.Task<'Source>
<Extension()>
Public Function FirstAsync(Of TSource) (source As IQueryable(Of TSource)) 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.

Returns

Task<TSource>

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

Exceptions

source is null.

The source sequence is empty.

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.

Applies to

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

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

[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures")]
public static System.Threading.Tasks.Task<TSource> FirstAsync<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,bool>> predicate);
static member FirstAsync : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, bool>> -> System.Threading.Tasks.Task<'Source>
<Extension()>
Public Function FirstAsync(Of TSource) (source As IQueryable(Of TSource), predicate As Expression(Of Func(Of TSource, Boolean))) 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.

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.

Attributes

Exceptions

source or predicate is null .

No element satisfies the condition in predicate .

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.

Applies to