MongoQueryable.FirstOrDefaultAsync(TSource) Method (IMongoQueryable(TSource), Expression(Func(TSource, Boolean)), CancellationToken) (original) (raw)
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: 2.10.0+569905ff5e778c38ea19d9d0392496a83e1704ed
Syntax
public static Task FirstOrDefaultAsync( this IMongoQueryable source, Expression<Func<TSource, bool>> predicate, CancellationToken cancellationToken = null )
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)[] 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