EntityFrameworkQueryableExtensions.FirstOrDefaultAsync Method
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Overloads
| FirstOrDefaultAsync<TSource>(IQueryable<TSource>, CancellationToken) |
Asynchronously returns the first element of a sequence, or a default value if the sequence contains no elements. |
| FirstOrDefaultAsync<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>, CancellationToken) |
Asynchronously returns the first element of a sequence that satisfies a specified condition or a default value if no such element is found. |
FirstOrDefaultAsync<TSource>(IQueryable<TSource>, CancellationToken)
Asynchronously returns the first element of a sequence, or a default value if the sequence contains no elements.
public static System.Threading.Tasks.Task<TSource> FirstOrDefaultAsync<TSource> (this System.Linq.IQueryable<TSource> source, System.Threading.CancellationToken cancellationToken = default);public static System.Threading.Tasks.Task<TSource?> FirstOrDefaultAsync<TSource> (this System.Linq.IQueryable<TSource> source, System.Threading.CancellationToken cancellationToken = default);static member FirstOrDefaultAsync : System.Linq.IQueryable<'Source> * System.Threading.CancellationToken -> System.Threading.Tasks.Task<'Source><Extension()>
Public Function FirstOrDefaultAsync(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 default ( TSource ) if
source is empty; otherwise, the first element in source.
Exceptions
source is null.
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
FirstOrDefaultAsync<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>, CancellationToken)
Asynchronously returns the first element of a sequence that satisfies a specified condition or a default value if no such element is found.
public static System.Threading.Tasks.Task<TSource> FirstOrDefaultAsync<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,bool>> predicate, System.Threading.CancellationToken cancellationToken = default);public static System.Threading.Tasks.Task<TSource?> FirstOrDefaultAsync<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,bool>> predicate, System.Threading.CancellationToken cancellationToken = default);static member FirstOrDefaultAsync : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, bool>> * System.Threading.CancellationToken -> System.Threading.Tasks.Task<'Source><Extension()>
Public Function FirstOrDefaultAsync(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 default ( TSource ) if source
is empty or if no element passes the test specified by predicate, otherwise, the first
element in source that passes the test specified by predicate.
Exceptions
source or predicate is null.
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
Entity Framework