QueryableExtensions::FirstOrDefaultAsync Method
Asynchronously returns the first element of a sequence, or a default value if the sequence contains no elements.
Assembly: EntityFramework (in EntityFramework.dll)
| Name | Description | |
|---|---|---|
  | FirstOrDefaultAsync<TSource>(IQueryable<TSource>^) | Asynchronously returns the first element of a sequence, or a default value if the sequence contains no elements. |
| 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>^>^) | 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>^, 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. |
QueryableExtensions::FirstOrDefaultAsync<TSource> Method (IQueryable<TSource>^)
Asynchronously returns the first element of a sequence, or a default value if the sequence contains no elements.
public: generic<typename TSource> [ExtensionAttribute] static Task<TSource>^ FirstOrDefaultAsync( IQueryable<TSource>^ source )
Parameters
- source
-
Type:
System.Linq::IQueryable<TSource>^
An IQueryable<T> to return the first element of.
Return Value
Type: System.Threading.Tasks::Task<TSource>^A task that represents the asynchronous operation. The task result contains default ( TSource ) if source is empty; otherwise, the first element in source.
Type Parameters
- TSource
The type of the elements of source.
| Exception | Condition |
|---|---|
| ArgumentNullException | source is null . |
| InvalidOperationException | source does not implement IDbAsyncQueryProvider . |
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.
QueryableExtensions::FirstOrDefaultAsync<TSource> Method (IQueryable<TSource>^, CancellationToken)
Asynchronously returns the first element of a sequence, or a default value if the sequence contains no elements.
public: generic<typename TSource> [ExtensionAttribute] static Task<TSource>^ FirstOrDefaultAsync( IQueryable<TSource>^ source, CancellationToken cancellationToken )
Parameters
- source
-
Type:
System.Linq::IQueryable<TSource>^
An IQueryable<T> to return the first element of.
- cancellationToken
-
Type:
System.Threading::CancellationToken
A CancellationToken to observe while waiting for the task to complete.
Return Value
Type: System.Threading.Tasks::Task<TSource>^A task that represents the asynchronous operation. The task result contains default ( TSource ) if source is empty; otherwise, the first element in source.
Type Parameters
- TSource
The type of the elements of source.
| Exception | Condition |
|---|---|
| ArgumentNullException | source is null . |
| InvalidOperationException | source does not implement IDbAsyncQueryProvider . |
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.
QueryableExtensions::FirstOrDefaultAsync<TSource> Method (IQueryable<TSource>^, Expression<Func<TSource, Boolean>^>^)
Asynchronously returns the first element of a sequence that satisfies a specified condition or a default value if no such element is found.
public: generic<typename TSource> [ExtensionAttribute] [SuppressMessageAttribute("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures")] static Task<TSource>^ FirstOrDefaultAsync( IQueryable<TSource>^ source, Expression<Func<TSource, bool>^>^ predicate )
Parameters
- source
-
Type:
System.Linq::IQueryable<TSource>^
An IQueryable<T> to return the first element of.
- predicate
-
Type:
System.Linq.Expressions::Expression<Func<TSource, Boolean>^>^
A function to test each element for a condition.
Return Value
Type: System.Threading.Tasks::Task<TSource>^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.
Type Parameters
- TSource
The type of the elements of source.
| Exception | Condition |
|---|---|
| ArgumentNullException | source or predicate is null . |
| InvalidOperationException | source does not implement IDbAsyncQueryProvider . |
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.
QueryableExtensions::FirstOrDefaultAsync<TSource> Method (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: generic<typename TSource> [ExtensionAttribute] [SuppressMessageAttribute("Microsoft.Design", "CA1011:ConsiderPassingBaseTypesAsParameters")] [SuppressMessageAttribute("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures")] static Task<TSource>^ FirstOrDefaultAsync( IQueryable<TSource>^ source, Expression<Func<TSource, bool>^>^ predicate, CancellationToken cancellationToken )
Parameters
- source
-
Type:
System.Linq::IQueryable<TSource>^
An IQueryable<T> to return the first element of.
- 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<TSource>^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.
Type Parameters
- TSource
The type of the elements of source.
| Exception | Condition |
|---|---|
| ArgumentNullException | source or predicate is null . |
| InvalidOperationException | source does not implement IDbAsyncQueryProvider . |
| InvalidOperationException | source has more than one element. |
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.