MongoQueryableFirstOrDefaultAsyncTSource Method (IQueryableTSource, CancellationToken) |
Returns the first element of a sequence, or a default value if the sequence contains no elements.
Namespace: MongoDB.Driver.LinqAssembly: MongoDB.Driver (in MongoDB.Driver.dll) Version: 2.1.0
Syntax public static Task<TSource> FirstOrDefaultAsync<TSource>(
this IQueryable<TSource> source,
CancellationToken cancellationToken = null
)
<ExtensionAttribute>
Public Shared Function FirstOrDefaultAsync(Of TSource) (
source As IQueryable(Of TSource),
Optional cancellationToken As CancellationToken = Nothing
) As Task(Of TSource)
[<ExtensionAttribute>]
static member FirstOrDefaultAsync :
source : IQueryable<'TSource> *
?cancellationToken : CancellationToken
(* Defaults:
let _cancellationToken = defaultArg cancellationToken null
*)
-> Task<'TSource>
Parameters
- source
- Type: System.LinqIQueryableTSource
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
IQueryableTSource. 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).
See Also