Queryable.OrderBy<TSource, TKey> Method (IQueryable<TSource>, Expression<Func<TSource, TKey>>)

public static IOrderedQueryable<TSource> OrderBy<TSource, TKey>(
	this IQueryable<TSource> source,
	Expression<Func<TSource, TKey>> keySelector
)

Usage Note

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 OrderBy<TSource, TKey>(IQueryable<TSource>, Expression<Func<TSource, TKey>>) method generates a MethodCallExpression that represents calling OrderBy<TSource, TKey>(IQueryable<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 OrderBy<TSource, TKey>(IQueryable<TSource>, Expression<Func<TSource, TKey>>) depends on the implementation of the type of the source parameter. The expected behavior is that it sorts the elements of source based on the key obtained by invoking keySelector on each element of source.

The following code example demonstrates how to use OrderBy<TSource, TKey>(IQueryable<TSource>, Expression<Func<TSource, TKey>>) to sort the elements of a sequence.

class Pet
{
    public string Name { get; set; }
    public int Age { get; set; }
}

public static void OrderByEx1()
{
    Pet[] pets = { new Pet { Name="Barley", Age=8 },
                   new Pet { Name="Boots", Age=4 },
                   new Pet { Name="Whiskers", Age=1 } };

    // Sort the Pet objects in the array by Pet.Age.
    IEnumerable<Pet> query =
        pets.AsQueryable().OrderBy(pet => pet.Age);

    foreach (Pet pet in query)
        Console.WriteLine("{0} - {1}", pet.Name, pet.Age);
}

/*
    This code produces the following output:

    Whiskers - 1
    Boots - 4
    Barley - 8
*/

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Reference