Queryable.AsQueryable(Of TElement) Method (IEnumerable(Of TElement))

Converts a generic IEnumerable(Of T) to a generic IQueryable(Of T).

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

'Declaration
<ExtensionAttribute> _
Public Shared Function AsQueryable(Of TElement) ( _
	source As IEnumerable(Of TElement) _
) As IQueryable(Of TElement)

Type Parameters

TElement

The type of the elements of source.

Parameters

source
Type: System.Collections.Generic.IEnumerable(Of TElement)

A sequence to convert.

Return Value

Type: System.Linq.IQueryable(Of TElement)
An IQueryable(Of T) that represents the input sequence.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable(Of TElement). 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 is Nothing.

If the type of source implements IQueryable(Of T), AsQueryable(Of TElement)(IEnumerable(Of TElement)) returns it directly. Otherwise, it returns an IQueryable(Of T) that executes queries by calling the equivalent query operator methods in Enumerable instead of those in Queryable.

The following code example demonstrates how to use AsQueryable(Of TElement)(IEnumerable(Of TElement)) to convert an IEnumerable(Of T) to an IQueryable(Of T).

        Dim grades As New List(Of Integer)(New Integer() {78, 92, 100, 37, 81})

        ' Convert the List to an IQueryable<int>. 
        Dim iqueryable As IQueryable(Of Integer) = grades.AsQueryable()

        ' Get the Expression property of the IQueryable object. 
        Dim expressionTree As System.Linq.Expressions.Expression = _
            iqueryable.Expression

        MsgBox("The NodeType of the expression tree is: " _
            & expressionTree.NodeType.ToString())
        MsgBox("The Type of the expression tree is: " _
            & expressionTree.Type.Name)

        ' This code produces the following output: 
        
        ' The NodeType of the expression tree is: Constant 
        ' The Type of the expression tree is: EnumerableQuery`1

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
Was this page helpful?
(1500 characters remaining)
Thank you for your feedback
Show:
© 2015 Microsoft