Queryable.ThenBy<'TSource, 'TKey> Method (IOrderedQueryable<'TSource>, Expression<Func<'TSource, 'TKey>>)
Performs a subsequent ordering of the elements in a sequence in ascending order according to a key.
Assembly: System.Core (in System.Core.dll)
static member ThenBy<'TSource, 'TKey> : source:IOrderedQueryable<'TSource> * keySelector:Expression<Func<'TSource, 'TKey>> -> IOrderedQueryable<'TSource>
Parameters
- source
-
Type:
System.Linq.IOrderedQueryable<'TSource>
An IOrderedQueryable<'T> that contains elements to sort.
- keySelector
-
Type:
System.Linq.Expressions.Expression<Func<'TSource, 'TKey>>
A function to extract a key from each element.
Return Value
Type: System.Linq.IOrderedQueryable<'TSource>An IOrderedQueryable<'T> whose elements are sorted according to a key.
Type Parameters
- TSource
The type of the elements of source.
- TKey
The type of the key returned by the function represented by keySelector.
| Exception | Condition |
|---|---|
| ArgumentNullException | source or keySelector is null. |
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 ThenBy<'TSource, 'TKey>(IOrderedQueryable<'TSource>, Expression<Func<'TSource, 'TKey>>) method generates a MethodCallExpression that represents calling ThenBy<'TSource, 'TKey>(IOrderedQueryable<'TSource>, Expression<Func<'TSource, 'TKey>>) itself as a constructed generic method. It then passes the MethodCallExpression to the CreateQuery<'TElement>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter. The result of calling CreateQuery<'TElement>(Expression) is cast to type IOrderedQueryable<'T> and returned.
The query behavior that occurs as a result of executing an expression tree that represents calling ThenBy<'TSource, 'TKey>(IOrderedQueryable<'TSource>, Expression<Func<'TSource, 'TKey>>) depends on the implementation of the type of the source parameter. The expected behavior is that it performs a secondary sort of the elements of source based on the key obtained by invoking keySelector on each element of source. All previously established sort orders are preserved.
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1