DbRawSqlQuery<TElement>.SingleOrDefaultAsync Method

 

Asynchronously returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.

Namespace:   System.Data.Entity.Infrastructure
Assembly:  EntityFramework (in EntityFramework.dll)

NameDescription
System_CAPS_pubmethodSingleOrDefaultAsync()

Asynchronously returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.

System_CAPS_pubmethodSingleOrDefaultAsync(CancellationToken)

Asynchronously returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.

System_CAPS_pubmethodSingleOrDefaultAsync(Func<TElement, Boolean>)

Asynchronously returns the only element of the query that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.

System_CAPS_pubmethodSingleOrDefaultAsync(Func<TElement, Boolean>, CancellationToken)

Asynchronously returns the only element of the query that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.


DbRawSqlQuery<TElement>.SingleOrDefaultAsync Method ()

Asynchronously returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.

public Task<TElement> SingleOrDefaultAsync()

Return Value

Type: System.Threading.Tasks.Task<TElement>

A task that represents the asynchronous operation. The task result contains the single element of the query result, or default ( TElement ) if the sequence contains no elements.

Exception Condition
InvalidOperationException

The query result 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.


DbRawSqlQuery<TElement>.SingleOrDefaultAsync Method (CancellationToken)

Asynchronously returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.

public Task<TElement> SingleOrDefaultAsync(
	CancellationToken cancellationToken
)

Parameters

cancellationToken
Type: System.Threading.CancellationToken

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

Return Value

Type: System.Threading.Tasks.Task<TElement>

A task that represents the asynchronous operation. The task result contains the single element of the query result, or default ( TElement ) if the sequence contains no elements.

Exception Condition
InvalidOperationException

The query result 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.


DbRawSqlQuery<TElement>.SingleOrDefaultAsync Method (Func<TElement, Boolean>)

Asynchronously returns the only element of the query that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.

public Task<TElement> SingleOrDefaultAsync(
	Func<TElement, bool> predicate
)

Parameters

predicate
Type: System.Func<TElement, Boolean>

A function to test each element for a condition.

Return Value

Type: System.Threading.Tasks.Task<TElement>

A task that represents the asynchronous operation. The task result contains the single element of the query result that satisfies the condition in predicate, or default ( TElement ) if no such element is found.

Exception Condition
ArgumentNullException

predicate is null .

InvalidOperationException

More than one element satisfies the condition in predicate .

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.


DbRawSqlQuery<TElement>.SingleOrDefaultAsync Method (Func<TElement, Boolean>, CancellationToken)

Asynchronously returns the only element of the query that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.

public Task<TElement> SingleOrDefaultAsync(
	Func<TElement, bool> predicate,
	CancellationToken cancellationToken
)

Parameters

predicate
Type: System.Func<TElement, 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<TElement>

A task that represents the asynchronous operation. The task result contains the single element of the query result that satisfies the condition in predicate, or default ( TElement ) if no such element is found.

Exception Condition
ArgumentNullException

predicate is null .

InvalidOperationException

More than one element satisfies the condition in predicate .

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.