MongoQueryableFirstOrDefaultAsyncTSource Method (IMongoQueryableTSource, CancellationToken)

Returns the first element of a sequence, or a default value if the sequence contains no elements.

Namespace: MongoDB.Driver.Linq
Assembly: MongoDB.Driver (in MongoDB.Driver.dll) Version: 2.9.0+32b058abcdf2c7e8d9dd3a676d207b31897eee2e

Syntax

Copy

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

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

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

Parameters

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

Type Parameters

TSource: The type of the elements of source.

Return Value

Type: TaskTSource
default(TSource) if source is empty; otherwise, the first element in source.

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

FirstOrDefaultAsync Overload

MongoDB.Driver.Linq Namespace