MongoQueryableFirstOrDefaultAsyncTSource Method (IMongoQueryableTSource, ExpressionFuncTSource, Boolean, CancellationToken) |
Returns the first element of a sequence that satisfies a specified condition or a default value if no such element is found.
Namespace:
MongoDB.Driver.Linq
Assembly:
MongoDB.Driver (in MongoDB.Driver.dll) Version: 2.7.3+Branch.v2.7.x.Sha.2f1f2be13a23b8520cb9c2ee8439c022f9a03efe
Syntax public static Task<TSource> FirstOrDefaultAsync<TSource>(
this IMongoQueryable<TSource> source,
Expression<Func<TSource, bool>> predicate,
CancellationToken cancellationToken = null
)
<ExtensionAttribute>
Public Shared Function FirstOrDefaultAsync(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 FirstOrDefaultAsync :
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 an element from. - predicate
- Type: System.Linq.ExpressionsExpressionFuncTSource, Boolean
A function to test each 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
default(
TSource) if
source is empty or if no element passes the test specified by
predicate; otherwise, the first element in
source that passes the test specified by
predicate.
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