ParseChildrenAttribute Class
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ParseChildrenAttribute Class

 

Defines a metadata attribute that you can use when developing ASP.NET server controls. Use the ParseChildrenAttribute class to indicate how the page parser should treat content nested inside a server control tag declared on a page. This class cannot be inherited.

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

System.Object
  System.Attribute
    System.Web.UI.ParseChildrenAttribute

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

NameDescription
System_CAPS_pubmethodParseChildrenAttribute()

Initializes a new instance of the ParseChildrenAttribute class.

System_CAPS_pubmethodParseChildrenAttribute(Boolean)

Initializes a new instance of the ParseChildrenAttribute class using the ChildrenAsProperties property to determine if the elements that are contained within a server control are parsed as properties of the server control.

System_CAPS_pubmethodParseChildrenAttribute(Boolean, String)

Initializes a new instance of the ParseChildrenAttribute class using the childrenAsProperties and defaultProperty parameters.

System_CAPS_pubmethodParseChildrenAttribute(Type)

Initializes a new instance of the ParseChildrenAttribute class using the ChildControlType property to determine which elements that are contained within a server control are parsed as controls.

NameDescription
System_CAPS_pubpropertyChildControlType

Gets a value indicating the allowed type of a control.

System_CAPS_pubpropertyChildrenAsProperties

Gets or sets a value indicating whether to parse the elements that are contained within a server control as properties.

System_CAPS_pubpropertyDefaultProperty

Gets or sets the default property for the server control into which the elements are parsed.

System_CAPS_pubpropertyTypeId

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

NameDescription
System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Overrides Attribute.Equals(Object).)

System_CAPS_pubmethodGetHashCode()

Serves as a hash function for the ParseChildrenAttribute object.(Overrides Attribute.GetHashCode().)

System_CAPS_pubmethodGetType()

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

System_CAPS_pubmethodIsDefaultAttribute()

Returns a value indicating whether the value of the current instance of the ParseChildrenAttribute class is the default value of the derived class.(Overrides Attribute.IsDefaultAttribute().)

System_CAPS_pubmethodMatch(Object)

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

System_CAPS_pubmethodToString()

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

NameDescription
System_CAPS_pubfieldSystem_CAPS_staticDefault

Defines the default value for the ParseChildrenAttribute class. This field is read-only.

System_CAPS_pubfieldSystem_CAPS_staticParseAsChildren

Indicates that the nested content that is contained within the server control is parsed as controls.

System_CAPS_pubfieldSystem_CAPS_staticParseAsProperties

Indicates that the nested content that is contained within a server control is parsed as properties of the control.

NameDescription
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.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfoCount(UInt32)

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.)

The ParseChildrenAttribute class allows you to specify parsing logic for a custom server control by marking the server control with the ParseChildrenAttribute metadata attribute.

Marking your server control with the metadata attribute ParseChildren(true) instructs the parser to interpret the elements that are contained within the server control's tags as properties. In this scenario, the ChildrenAsProperties property is true.

Marking your server control with the metadata attribute ParseChildren(true,"<Default Property>") sets the DefaultProperty property to the name of the property that is passed into the attribute.

Marking your server control with the metadata attribute ParseChildren(false), the default value, instructs the parser to interpret the elements that are contained within the server control's tags as content that will be parsed with an associated ControlBuilder that is, as controls. In this scenario, the ChildrenAsProperties property is false.

For information about using attributes, see Extending Metadata Using Attributes.

The code example in this section contains two parts. The first code example demonstrates how to set properties for the ParseChildrenAttribute class. The second code example demonstrates how to use classes in an ASP.NET page.

The following code example demonstrates how to set the ParseChildrenAttribute object of a custom server control named CollectionPropertyControl. The ParseChildrenAttribute sets the ChildrenAsProperties property to true and the DefaultProperty property to the Employee class.

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

namespace Samples.AspNet.CS.Controls
{
   // The child element class.
   [AspNetHostingPermission(SecurityAction.Demand, 
      Level=AspNetHostingPermissionLevel.Minimal)]
   public sealed class Employee
   {
      private String name;
      private String title;
      private String alias;

      public Employee():this ("","",""){}

      public Employee (String name, String title, String alias)
      {
         this.name = name;
         this.title = title;
         this.alias = alias;
      }
      public String Name
      {
         get
         {
            return name;
         }
         set
         {
            name = value;
         }
      }

      public String Title
      {
         get
         {
            return title;
         }
         set
         {
            title = value;
         }
      }

      public String Alias
      {
         get
         {
            return alias;
         }
         set
         {
            alias = value;
         }
      }
   }
   // Use the ParseChildren attribute to set the ChildrenAsProperties
   // and DefaultProperty properties. Using this constructor, the
   // control parses all child controls as properties and must define
   // a public property named Employees, which it declares as
   // an ArrayList. Nested (child) elements must correspond to
   // child elements of the Employees property or to other
   // properties of the control.  
   [ParseChildren(true, "Employees")]
   [AspNetHostingPermission(SecurityAction.Demand, 
      Level=AspNetHostingPermissionLevel.Minimal)]
   public sealed class CollectionPropertyControl : Control
   {  
      private String header;
      private ArrayList employees = new ArrayList();

      public String Header
      {
         get
         {
            return header;
         }
         set
         {
            header = value;
         }
      }



      public ArrayList Employees
      {
         get 
         {
            return employees;
         }
      }
      // Override the CreateChildControls method to 
      // add child controls to the Employees property when this
      // custom control is requested from a page.
      protected override void CreateChildControls()
      {
         Label label = new Label();
         label.Text = Header;
         label.BackColor = System.Drawing.Color.Beige;
         label.ForeColor = System.Drawing.Color.Red;
         Controls.Add(label);
         Controls.Add(new LiteralControl("<BR> <BR>"));

         Table table = new Table();
         TableRow htr = new TableRow();

         TableHeaderCell hcell1 = new TableHeaderCell();    
         hcell1.Text = "Name";
         htr.Cells.Add(hcell1);

         TableHeaderCell hcell2 = new TableHeaderCell();
         hcell2.Text = "Title";
         htr.Cells.Add(hcell2);

         TableHeaderCell hcell3 = new TableHeaderCell();
         hcell3.Text = "Alias";
         htr.Cells.Add(hcell3);
         table.Rows.Add(htr);

         table.BorderWidth = 2;
         table.BackColor = System.Drawing.Color.Beige;
         table.ForeColor = System.Drawing.Color.Red;
         foreach (Employee employee in Employees)
         {
            TableRow tr = new TableRow();

            TableCell cell1 = new TableCell();
            cell1.Text = employee.Name;
            tr.Cells.Add(cell1);

            TableCell cell2 = new TableCell();
            cell2.Text = employee.Title;
            tr.Cells.Add(cell2);

            TableCell cell3 = new TableCell();
            cell3.Text = employee.Alias;
            tr.Cells.Add(cell3);

            table.Rows.Add(tr);
         }
         Controls.Add(table);

      }
   }
}

The following code example demonstrates how to use the CollectionPropertyControl and Employee classes in an ASP.NET page. Instances of the Employee class are added declaratively.

<%@ Page Language="C#" Debug="true" %>
<%@ Register TagPrefix="AspSample" Assembly="Samples.AspNet.CS.Controls" Namespace="Samples.AspNet.CS.Controls" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

  protected void Page_Load(object sender, EventArgs e)
  {

    // Verify attribute values.
    ParseChildrenAttribute p = 
      (ParseChildrenAttribute)Attribute.GetCustomAttribute(typeof(CollectionPropertyControl),
      typeof(ParseChildrenAttribute));

    StringBuilder sb = new StringBuilder();
    sb.Append("The DefaultProperty property is " + p.DefaultProperty.ToString() + "<br />");
    sb.Append("The ChildrenAsProperties property is " + p.ChildrenAsProperties.ToString() + "<br />");
    sb.Append("The IsDefaultAttribute method returns " + p.IsDefaultAttribute().ToString());
    Message.Text = sb.ToString();

  }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>ParseChildrenAttribute Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
      <asp:Label ID="Message"
                 runat="server"/>
      <AspSample:CollectionPropertyControl id="CollectionPropertyControl1" 
                                           runat="server">
        <AspSample:Employee Name="Employee 1" 
                            Title="Title 1" 
                            Alias="Alias 1" />
        <AspSample:Employee Name="Employee 2" 
                            Title="Title 2" 
                            Alias="Alias 2" />
      </AspSample:CollectionPropertyControl>    
    </div>
    </form>
</body>
</html>

.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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