IAsyncCursorSourceExtensionsSingleOrDefaultAsyncTDocument Method

Returns the only document of a cursor returned by a cursor source, or a default value if the cursor contains no documents. This method throws an exception if the cursor contains more than one document.

Namespace: MongoDB.Driver
Assembly: MongoDB.Driver.Core (in MongoDB.Driver.Core.dll) Version: 2.16.0+eeafbea0921243a5868b81984e1083a07c1f75bc

Syntax

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public static Task<TDocument> SingleOrDefaultAsync<TDocument>(
	this IAsyncCursorSource<TDocument> source,
	CancellationToken cancellationToken = default
)

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

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

Parameters

source: Type: MongoDB.DriverIAsyncCursorSourceTDocument
The source.
cancellationToken (Optional): Type: System.ThreadingCancellationToken
The cancellation token.

Type Parameters

TDocument: The type of the document.

Return Value

Type: TaskTDocument
A Task whose result is the only document of a cursor, or a default value if the cursor contains no documents.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IAsyncCursorSourceTDocument. 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

IAsyncCursorSourceExtensions Class