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ControlBuilderAttribute Class

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

System.Object
  System.Attribute
    System.Web.UI.ControlBuilderAttribute

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

[AttributeUsageAttribute(AttributeTargets.Class)]
public sealed class ControlBuilderAttribute : Attribute

The ControlBuilderAttribute type exposes the following members.

  NameDescription
Public methodControlBuilderAttributeInfrastructure. Specifies the control builder for a custom control.
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  NameDescription
Public propertyBuilderTypeGets the Type of the control associated with the attribute. This property is read-only.
Public propertyTypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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  NameDescription
Public methodEqualsInfrastructure. Gets a value indicating whether the current ControlBuilderAttribute is identical to the specified object. (Overrides Attribute.Equals(Object).)
Public methodGetHashCodeInfrastructure. Returns the hash code of the ControlBuilderAttribute object. (Overrides Attribute.GetHashCode().)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsDefaultAttributeInfrastructure. Determines whether the current control builder is the default. (Overrides Attribute.IsDefaultAttribute().)
Public methodMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Public fieldStatic memberDefaultInfrastructure. Specifies the new ControlBuilderAttribute object. By default, the new object is set to null. This field is read-only.
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  NameDescription
Explicit interface implemetationPrivate method_Attribute.GetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.InvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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This attribute specifies the builder Type to be used to create a custom control as shown in the following code:

[ControlBuilderAttribute(typeof(ControlBuilderType))]

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 
      {
        get 
        {
          return _message;
        }
        set 
        {
           _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;
      }
    }


    [ 
       ControlBuilderAttribute(typeof(CustomParseControlBuilder)) 
    ]
    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 
       { 
           get 
           {
              return _selectedIndex;
           }
           set 
           {
              _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) 
         {
              _items.Add(obj);
           }
       }

       [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"/>
  </custom:MyCS_CustomParse>
 </form>

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 8.1, Windows Server 2012 R2, 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.

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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