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

Sorts the elements of a sequence in ascending order according to a key.

Namespace:  System.Linq
Assemblies:   System.Linq.Queryable (in System.Linq.Queryable.dll)
  System.Core (in System.Core.dll)

'Declaration
<ExtensionAttribute> _
Public Shared Function OrderBy(Of TSource, TKey) ( _
	source As IQueryable(Of TSource), _
	keySelector As Expression(Of Func(Of TSource, TKey)) _
) As IOrderedQueryable(Of TSource)

Type Parameters

TSource

The type of the elements of source.

TKey

The type of the key returned by the function that is represented by keySelector.

Parameters

source
Type: System.Linq.IQueryable(Of TSource)

A sequence of values to order.

keySelector
Type: System.Linq.Expressions.Expression(Of Func(Of TSource, TKey))

A function to extract a key from an element.

Return Value

Type: System.Linq.IOrderedQueryable(Of TSource)
An IOrderedQueryable(Of T) whose elements are sorted according to a key.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable(Of TSource). 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).

ExceptionCondition
ArgumentNullException

source or keySelector is Nothing.

This method has at least one parameter of type Expression(Of TDelegate) whose type argument is one of the Func(Of T, TResult) types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression(Of TDelegate).

The OrderBy(Of TSource, TKey)(IQueryable(Of TSource), Expression(Of Func(Of TSource, TKey))) method generates a MethodCallExpression that represents calling OrderBy(Of TSource, TKey)(IQueryable(Of TSource), Expression(Of Func(Of TSource, TKey))) itself as a constructed generic method. It then passes the MethodCallExpression to the CreateQuery(Of TElement)(Expression) method of the IQueryProvider represented by the Provider property of the source parameter. The result of calling CreateQuery(Of TElement)(Expression) is cast to type IOrderedQueryable(Of T) and returned.

The query behavior that occurs as a result of executing an expression tree that represents calling OrderBy(Of TSource, TKey)(IQueryable(Of TSource), Expression(Of Func(Of 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(Of TSource, TKey)(IQueryable(Of TSource), Expression(Of Func(Of TSource, TKey))) to sort the elements of a sequence.

    Structure Pet
        Public Name As String 
        Public Age As Integer 
    End Structure 

    Shared Sub OrderByEx1()
        Dim pets() As Pet = {New Pet With {.Name = "Barley", .Age = 8}, _
                             New Pet With {.Name = "Boots", .Age = 4}, _
                             New Pet With {.Name = "Whiskers", .Age = 1}}

        ' Sort the Pet objects in the array by Pet.Age. 
        Dim query As IEnumerable(Of Pet) = _
                    pets.AsQueryable().OrderBy(Function(pet) pet.Age)

        Dim output As New System.Text.StringBuilder
        For Each pet As Pet In query
            output.AppendLine(String.Format("{0} - {1}", pet.Name, pet.Age))
        Next 

        ' Display the output.
        MsgBox(output.ToString())
    End Sub 

    ' This code produces the following output: 

    ' Whiskers - 1 
    ' Boots - 4 
    ' Barley - 8

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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