Queryable.OfType<TResult> Method
Filters the elements of an IQueryable based on a specified type.
Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)
Type Parameters
- TResult
The type to filter the elements of the sequence on.
Parameters
- source
- Type: System.Linq.IQueryable
An IQueryable whose elements to filter.
Return Value
Type: System.Linq.IQueryable<TResult>A collection that contains the elements from source that have type TResult.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable. 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).| Exception | Condition |
|---|---|
| ArgumentNullException | source is null. |
The OfType method generates a MethodCallExpression that represents calling OfType 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 OfType depends on the implementation of the type of the source parameter. The expected behavior is that it filters out any elements in source that are not of type TResult.
The following code example demonstrates how to use OfType to filter out elements that are not of type PropertyInfo from a list of elements of type MemberInfo.
// Create a list of MemberInfo objects.
List<System.Reflection.MemberInfo> members = typeof(String).GetMembers().ToList();
// Return only those items that can be cast to type PropertyInfo.
IQueryable<System.Reflection.PropertyInfo> propertiesOnly =
members.AsQueryable().OfType<System.Reflection.PropertyInfo>();
Console.WriteLine("Members of type 'PropertyInfo' are:");
foreach (System.Reflection.PropertyInfo pi in propertiesOnly)
Console.WriteLine(pi.Name);
/*
This code produces the following output:
Members of type 'PropertyInfo' are:
Chars
Length
*/
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.
