Cast(TResult) Method

Queryable.Cast<TResult> Method (IQueryable)


Converts the elements of an IQueryable to the specified type.

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

public static IQueryable<TResult> Cast<TResult>(
	this IQueryable source


Type: System.Linq.IQueryable

The IQueryable that contains the elements to be converted.

Return Value

Type: System.Linq.IQueryable<TResult>

An IQueryable<T> that contains each element of the source sequence converted to the specified type.

Type Parameters


The type to convert the elements of source to.

Exception Condition

source is null.


An element in the sequence cannot be cast to type TResult.

The Cast<TResult>(IQueryable) method generates a MethodCallExpression that represents calling Cast<TResult>(IQueryable) itself as a constructed generic method. It then passes the MethodCallExpression to the CreateQuery(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling Cast<TResult>(IQueryable) depends on the implementation of the type of the source parameter. The expected behavior is that it converts the values in source to type TResult.

The following code example demonstrates how to use Cast<TResult>(IQueryable) to convert objects in a sequence to type String.

// Create a list of objects.
List<object> words =
    new List<object> { "green", "blue", "violet" };

// Cast the objects in the list to type 'string'
// and project the first letter of each string.
IEnumerable<string> query =
    .Select(str => str.Substring(0, 1));

foreach (string s in query)

/*  This code produces the following output:


Universal Windows Platform
Available since 4.5
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1
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