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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: 2.20.0+ee01960089f28ea1b501690df5fc9f6318a70242
Syntax
public static Task<TSource> FirstOrDefaultAsync<TSource>(
	this IMongoQueryable<TSource> source,
	Expression<Func<TSource, bool>> predicate,
	CancellationToken cancellationToken = null
)

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