Queryable.OfType<(Of <(TResult>)>) Method

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Filters the elements of an IQueryable based on a specified type.

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


<ExtensionAttribute> _
Public Shared Function OfType(Of TResult) ( _
    source As IQueryable _
) As IQueryable(Of TResult)
public static IQueryable<TResult> OfType<TResult>(
    this IQueryable source

Type Parameters

  • TResult
    The type to filter the elements of the sequence on.


Return Value

Type: System.Linq..::.IQueryable<(Of <(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.


Exception Condition

source is nullNothingnullptra null reference (Nothing in Visual Basic).


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.
      Dim members As List(Of System.Reflection.MemberInfo) = GetType(String).GetMembers().ToList()

      ' Return only those items that can be cast to type PropertyInfo.
      Dim propertiesOnly As IQueryable(Of System.Reflection.PropertyInfo) = _
              members.AsQueryable().OfType(Of System.Reflection.PropertyInfo)()

      Dim output As New System.Text.StringBuilder
      output.AppendLine("Members of type 'PropertyInfo' are:")
      For Each pi As System.Reflection.PropertyInfo In propertiesOnly

      ' Display the output.
      outputBlock.Text &= output.ToString() & vbCrLf

      ' This code produces the following output:

      ' Members of type 'PropertyInfo' are:
      ' Chars
      ' Length
         // 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 =

         outputBlock.Text += "Members of type 'PropertyInfo' are:" + "\n";
         foreach (System.Reflection.PropertyInfo pi in propertiesOnly)
            outputBlock.Text += pi.Name + "\n";

             This code produces the following output:

             Members of type 'PropertyInfo' are:

Version Information

Windows Phone OS

Supported in: 8.1, 8.0, 7.1


Windows Phone

See Also


Queryable Class

System.Linq Namespace