MongoQueryable.SingleOrDefaultAsync<TSource> Method (IMongoQueryable<TSource>, 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: 2.22.0+75246110ed1247226fcc7f8eb2c54ffab745693e

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.Linq.IMongoQueryable<TSource>
An IMongoQueryable<T> to return the single element of.
cancellationToken (Optional): Type: System.Threading.CancellationToken
The cancellation token.

Type Parameters

TSource: The type of the elements of source.

Return Value

Type: Task<TSource>
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 IMongoQueryable<TSource>. 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