MongoQueryableSingleOrDefaultAsyncTSource Method (IMongoQueryableTSource, CancellationToken)

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: MongoDB.Driver.Linq
Assembly: MongoDB.Driver (in MongoDB.Driver.dll) Version: 2.21.0+5a9c3311e158910b88195f290e6d4b1b2715d2b2

Syntax

Copy

public static Task<TSource> SingleOrDefaultAsync<TSource>(
	this IMongoQueryable<TSource> source,
	CancellationToken cancellationToken = null
)

<ExtensionAttribute>
Public Shared Function SingleOrDefaultAsync(Of TSource) ( 
	source As IMongoQueryable(Of TSource),
	Optional cancellationToken As CancellationToken = Nothing
) As Task(Of TSource)

[<ExtensionAttribute>]
static member SingleOrDefaultAsync : 
        source : IMongoQueryable<'TSource> * 
        ?cancellationToken : CancellationToken 
(* Defaults:
        let _cancellationToken = defaultArg cancellationToken null
*)
-> Task<'TSource>

Parameters

source: Type: MongoDB.Driver.LinqIMongoQueryableTSource
An IMongoQueryableT to return the single element of.
cancellationToken (Optional): Type: System.ThreadingCancellationToken
The cancellation token.

Type Parameters

TSource: The type of the elements of source.

Return Value

Type: TaskTSource
The single element of the input sequence, or default(TSource) if the sequence contains no elements.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IMongoQueryableTSource. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

Reference

MongoQueryable Class

SingleOrDefaultAsync Overload

MongoDB.Driver.Linq Namespace