MongoQueryableSingleOrDefaultAsyncTSource Method (IMongoQueryableTSource, ExpressionFuncTSource, Boolean, CancellationToken) |
Returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.
Namespace:
MongoDB.Driver.Linq
Assembly:
MongoDB.Driver (in MongoDB.Driver.dll) Version: 2.5.0+57.Branch.master.Sha.6a4e00a2d91090c65a9b11364b9ebfdb9c7da076
Syntax public static Task<TSource> SingleOrDefaultAsync<TSource>(
this IMongoQueryable<TSource> source,
Expression<Func<TSource, bool>> predicate,
CancellationToken cancellationToken = null
)
<ExtensionAttribute>
Public Shared Function SingleOrDefaultAsync(Of TSource) (
source As IMongoQueryable(Of TSource),
predicate As Expression(Of Func(Of TSource, Boolean)),
Optional cancellationToken As CancellationToken = Nothing
) As Task(Of TSource)
[<ExtensionAttribute>]
static member SingleOrDefaultAsync :
source : IMongoQueryable<'TSource> *
predicate : Expression<Func<'TSource, bool>> *
?cancellationToken : CancellationToken
(* Defaults:
let _cancellationToken = defaultArg cancellationToken null
*)
-> Task<'TSource>
Parameters
- source
- Type: MongoDB.Driver.LinqIMongoQueryableTSource
An IMongoQueryableT to return a single element from. - predicate
- Type: System.Linq.ExpressionsExpressionFuncTSource, Boolean
A function to test an element for a condition. - 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 that satisfies the condition in
predicate, or default(
TSource) if no such element is found.
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).
See Also