Queryable::LastOrDefault<TSource> Method (IQueryable<TSource>, Expression<Func<TSource, Boolean>>)
Returns the last element of a sequence that satisfies a condition or a default value if no such element is found.
Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)
Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- Type: System.Linq::IQueryable<TSource>
An IQueryable<T> to return an element from.
- predicate
- Type: System.Linq.Expressions::Expression<Func<TSource, Boolean>>
A function to test each element for a condition.
Return Value
Type: TSourcedefault(TSource) if source is empty or if no elements pass the test in the predicate function; otherwise, the last element of source that passes the test in the predicate function.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable<TSource>. When you use instance method syntax to call this method, omit the first parameter.| Exception | Condition |
|---|---|
| ArgumentNullException | source or predicate is nullptr. |
This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T, TResult> types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.
The LastOrDefault<TSource>(IQueryable<TSource>) method generates a MethodCallExpression that represents calling LastOrDefault<TSource>(IQueryable<TSource>) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.
The query behavior that occurs as a result of executing an expression tree that represents calling LastOrDefault<TSource>(IQueryable<TSource>) depends on the implementation of the type of the source parameter. The expected behavior is that it returns the last element in source that satisfies the condition specified by predicate. It returns a default value if there is no such element in source.
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