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ParseChildrenAttribute Class

.NET Framework 4.5

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.

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

Namespace:  System.Web.UI
Assembly:  System.Web (in System.Web.dll)
C#
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F#
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[AttributeUsageAttribute(AttributeTargets.Class)]
public sealed class ParseChildrenAttribute : Attribute

The ParseChildrenAttribute type exposes the following members.

  NameDescription
Public methodParseChildrenAttribute()Initializes a new instance of the ParseChildrenAttribute class.
Public methodParseChildrenAttribute(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.
Public methodParseChildrenAttribute(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.
Public methodParseChildrenAttribute(Boolean, String)Initializes a new instance of the ParseChildrenAttribute class using the childrenAsProperties and defaultProperty parameters.
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  NameDescription
Public propertyChildControlTypeGets a value indicating the allowed type of a control.
Public propertyChildrenAsPropertiesGets or sets a value indicating whether to parse the elements that are contained within a server control as properties.
Public propertyDefaultPropertyGets or sets the default property for the server control into which the elements are parsed.
Public propertyTypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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  NameDescription
Public methodEqualsDetermines whether the specified object is equal to the current object. (Overrides Attribute.Equals(Object).)
Public methodGetHashCodeServes as a hash function for the ParseChildrenAttribute object. (Overrides Attribute.GetHashCode().)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsDefaultAttributeReturns 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().)
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 memberDefaultDefines the default value for the ParseChildrenAttribute class. This field is read-only.
Public fieldStatic memberParseAsChildrenIndicates that the nested content that is contained within the server control is parsed as controls.
Public fieldStatic memberParseAsPropertiesIndicates that the nested content that is contained within a server control is parsed as properties of the control.
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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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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.

TopicLocation
Walkthrough: Developing and Using a Custom Server ControlAuthoring ASP.NET Controls
Walkthrough: Developing and Using a Custom Server ControlAuthoring ASP.NET Controls

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.

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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.

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<%@ 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

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

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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