EntityFrameworkQueryableExtensions.FirstAsync Method
Definition
Important
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Overloads
| 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. |
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
A task that represents the asynchronous operation.
The task result contains the first element in source.
Exceptions
source is null.
source contains no elements.
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.
Applies to
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
A task that represents the asynchronous operation.
The task result contains the first element in source that passes the test in
predicate.
Exceptions
source or predicate is null.
No element satisfies the condition in predicate
-or -
source contains no elements.
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.
