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: 2.15.0+f503bf610759c13f78cff9a3c01e91453185d2ed

Syntax

Copy

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

<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 new CancellationToken()
*)
-> 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