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ControlBuilderAttribute Class


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Specifies a ControlBuilder class for building a custom control within the ASP.NET parser. This class cannot be inherited.

Namespace:   System.Web.UI
Assembly:  System.Web (in System.Web.dll)


public sealed class ControlBuilderAttribute : Attribute


This API supports the product infrastructure and is not intended to be used directly from your code. Specifies the control builder for a custom control.


Gets the Type of the control associated with the attribute. This property is read-only.


When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)


This API supports the product infrastructure and is not intended to be used directly from your code. Gets a value indicating whether the current ControlBuilderAttribute is identical to the specified object. (Overrides Attribute.Equals(Object).)


This API supports the product infrastructure and is not intended to be used directly from your code. Returns the hash code of the ControlBuilderAttribute object. (Overrides Attribute.GetHashCode().)


Gets the Type of the current instance.(Inherited from Object.)


This API supports the product infrastructure and is not intended to be used directly from your code. Determines whether the current control builder is the default.(Overrides Attribute.IsDefaultAttribute().)


When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)


Returns a string that represents the current object.(Inherited from Object.)


This API supports the product infrastructure and is not intended to be used directly from your code. Specifies the new ControlBuilderAttribute object. By default, the new object is set to null. This field is read-only.

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)


Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

This attribute specifies the builder Type to be used to create a custom control as shown in the following code:


The following code example creates a customized selection list that is used to display a message based on the SelectedIndex and the Message values defined at run time. The following command line is used to build the executable.

csc /t:library /out:myWebAppPath/Bin/cs_MyControlBuilderAtt.dll ControlBuilderAtt.cs

/* File name: controlBuilderAttribute.cs. */

using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;

namespace CustomControls

  public class MyCS_Item : Control 
  /* Class name: MyCS_Item. 
   * Defines the child control class.

      private String _message;

      public String Message 
          return _message;
           _message = value;

    public class CustomParseControlBuilder : ControlBuilder 
    /* Class name: CustomParserControlBuilder.
     * Defines the functions and data to be used in building custom controls. 
     * This class is referenced using the ControlBuilderAttribute class. See class below.
      [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
      public override Type GetChildControlType(String tagName, IDictionary attributes) 
        if (String.Compare(tagName, "customitem", true) == 0) 
           return typeof(MyCS_Item);
        return null;

    public class MyCS_CustomParse : Control 
    /* Class name: MyCS_CustomParse.
     * Performs custom parsing of a MyCS_CustomParse control type 
     * child control. 
     * If the child control is of the allowed type, it is added to an 
     * array list. This list is accessed, using the container control attribute 
     * SelectedIndex, to obtain the related child control Message attribute to be displayed.

       private ArrayList _items         = new ArrayList();
       private int       _selectedIndex = 0;

       public int SelectedIndex 
              return _selectedIndex;
              _selectedIndex = value;

       [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
       protected override void AddParsedSubObject(Object obj) 
       /* Function name: AddParsedSubObject.
        * Updates the array list with the allowed child objects.
        * This function is called during the parsing of the child controls and 
        * after the GetChildControlType function defined in the associated control 
        * builder class.
          if (obj is MyCS_Item) 

       [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
       protected override void Render(HtmlTextWriter output) 
       /* Function name: Render.
        * Establishes the rules to render the built control. In this case, a message is
        * rendered that is a function of the parent control SelectedIndex attribute and 
        * the related child Message attribute.
          if (SelectedIndex < _items.Count) 
              output.Write("<span style='background-color:aqua; color:red; font:8pt tahoma, verdana;'><b>" +
              ((MyCS_Item) _items[SelectedIndex]).Message + "</b></span>" );

The following example uses the custom control defined above. In particular, it assigns the SelectedIndex and Message values at run time to determine the message to be rendered. Notice that the values shown in the Register directive reflect the previous command line.

<%@ Register TagPrefix="custom" Assembly="myControlBuilderAtt" Namespace="CustomControls" %>
 <h4>Using ControlBuilderAttribute Class<h4>
 <form runat="server">
  <custom:MyCS_CustomParse SelectedIndex="2" runat=server>
  <customitem Message="C# version. Item One selected"/>
  <customitem Message="C# version. Item Two selected"/>
  <customitem Message="C# version. Item Three selected"/>
  <customitem Message="C# version. Item Four selected"/>

.NET Framework
Available since 1.1

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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