Queryable.AsQueryable<TElement> Method (IEnumerable<TElement>)

May 11, 2014

Converts a generic IEnumerable<T> to a generic IQueryable<T>.

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)

public static IQueryable<TElement> AsQueryable<TElement>(
	this IEnumerable<TElement> source
)

Type Parameters

TElement

The type of the elements of source.

Parameters

source
Type: System.Collections.Generic.IEnumerable<TElement>
A sequence to convert.

Return Value

Type: System.Linq.IQueryable<TElement>
An IQueryable<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<TElement>. When you use instance method syntax to call this method, omit the first parameter.

ExceptionCondition
ArgumentNullException

source is null.

If the type of source implements IQueryable<T>, AsQueryable<TElement>(IEnumerable<TElement>) returns it directly. Otherwise, it returns an IQueryable<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<TElement>(IEnumerable<TElement>) to convert an IEnumerable<T> to an IQueryable<T>.


List<int> grades = new List<int> { 78, 92, 100, 37, 81 };

// Convert the List to an IQueryable<int>.
IQueryable<int> iqueryable = grades.AsQueryable();

// Get the Expression property of the IQueryable object.
System.Linq.Expressions.Expression expressionTree =
    iqueryable.Expression;

outputBlock.Text += "The NodeType of the expression tree is: "
    + expressionTree.NodeType.ToString() + "\n";
outputBlock.Text += "The Type of the expression tree is: "
    + expressionTree.Type.Name + "\n";

/*
    This code produces the following output:

    The NodeType of the expression tree is: Constant
    The Type of the expression tree is: EnumerableQuery`1
*/


Windows Phone OS

Supported in: 8.1, 8.0, 7.1

Windows Phone

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