ParseChildrenAttribute Classe

Définition

public ref class ParseChildrenAttribute sealed : Attribute

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

[<System.AttributeUsage(System.AttributeTargets.Class)>]
type ParseChildrenAttribute = class
    inherit Attribute

Public NotInheritable Class ParseChildrenAttribute
Inherits Attribute

Héritage

Object

Attribute

ParseChildrenAttribute

Attributs

AttributeUsageAttribute

Exemples

L’exemple de code de cette section contient deux parties. Le premier exemple de code montre comment définir des propriétés pour la ParseChildrenAttribute classe. Le deuxième exemple de code montre comment utiliser des classes dans une page ASP.NET.

L’exemple de code suivant montre comment définir l’objet ParseChildrenAttribute d’un contrôle serveur personnalisé nommé CollectionPropertyControl. Définit ParseChildrenAttribute la ChildrenAsProperties propriété sur true et la DefaultProperty propriété sur la Employee classe.

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);
      }
   }
}

Imports System.Collections
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Security.Permissions

Namespace Samples.AspNet.VB.Controls


    ' The child element class.

    <AspNetHostingPermission(SecurityAction.Demand, _
       Level:=AspNetHostingPermissionLevel.Minimal)> _
    Public NotInheritable Class Employee
        Private _name As String
        Private _title As String
        Private _alias As String


        Public Sub New()
            Me.New("", "", "")
        End Sub


        Public Sub New(ByVal name As String, ByVal title As String, ByVal employeeAlias As String)
            Me._name = name
            Me._title = title
            Me._alias = employeeAlias
        End Sub

        Public Property Name() As String
            Get
                Return _name
            End Get
            Set(ByVal value As String)
                _name = Value
            End Set
        End Property


        Public Property Title() As String
            Get
                Return _title
            End Get
            Set(ByVal value As String)
                _title = Value
            End Set
        End Property


        Public Property [Alias]() As String
            Get
                Return _alias
            End Get
            Set(ByVal value As String)
                _alias = Value
            End Set
        End Property
    End Class
    ' 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 NotInheritable Class CollectionPropertyControl
        Inherits Control
        Private _header As String
        Private _employees As New ArrayList()


        Public Property Header() As String
            Get
                Return _header
            End Get
            Set(ByVal value As String)
                _header = Value
            End Set
        End Property




        Public ReadOnly Property Employees() As ArrayList
            Get
                Return _employees
            End Get
        End Property

        ' Override the CreateChildControls method to 
        ' add child controls to the Employees property when this
        ' custom control is requested from a page.
        Protected Overrides Sub CreateChildControls()
            Dim label As 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>"))

            Dim table As New Table()
            Dim htr As New TableRow()

            Dim hcell1 As New TableHeaderCell()
            hcell1.Text = "Name"
            htr.Cells.Add(hcell1)

            Dim hcell2 As New TableHeaderCell()
            hcell2.Text = "Title"
            htr.Cells.Add(hcell2)

            Dim hcell3 As New TableHeaderCell()
            hcell3.Text = "Alias"
            htr.Cells.Add(hcell3)
            table.Rows.Add(htr)

            table.BorderWidth = Unit.Pixel(2)
            table.BackColor = System.Drawing.Color.Beige
            table.ForeColor = System.Drawing.Color.Red
            Dim employee As Employee
            For Each employee In Employees
                Dim tr As New TableRow()

                Dim cell1 As New TableCell()
                cell1.Text = employee.Name
                tr.Cells.Add(cell1)

                Dim cell2 As New TableCell()
                cell2.Text = employee.Title
                tr.Cells.Add(cell2)

                Dim cell3 As New TableCell()
                cell3.Text = employee.Alias
                tr.Cells.Add(cell3)

                table.Rows.Add(tr)
            Next employee
            Controls.Add(table)
        End Sub
    End Class 
End Namespace

L’exemple de code suivant montre comment utiliser les CollectionPropertyControl classes d’une Employee page ASP.NET. Les instances de la Employee classe sont ajoutées de manière déclarative.

<%@ 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>

<%@ Page Language="VB" %>
<%@ Register TagPrefix="AspSample" Assembly="Samples.AspNet.VB.Controls" Namespace="Samples.AspNet.VB.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 Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
    
    ' Verify attribute values.
    Dim p As ParseChildrenAttribute = _
    Attribute.GetCustomAttribute(GetType(CollectionPropertyControl), _
    GetType(ParseChildrenAttribute))

    Dim sb As 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()

  End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>PersistChildrenAttribute</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>

Remarques

La ParseChildrenAttribute classe vous permet de spécifier la logique d’analyse d’un contrôle serveur personnalisé en marquant le contrôle serveur avec l’attribut ParseChildrenAttribute de métadonnées.

Le marquage de votre contrôle serveur avec l’attribut ParseChildren(true) de métadonnées indique à l’analyseur d’interpréter les éléments contenus dans les balises du contrôle serveur en tant que propriétés. Dans ce scénario, la ChildrenAsProperties propriété est true.

Le marquage de votre contrôle serveur avec l’attribut ParseChildren(true,"<Default Property>") de métadonnées définit la DefaultProperty propriété sur le nom de la propriété passée dans l’attribut.

Le marquage de votre contrôle serveur avec l’attribut ParseChildren(false)de métadonnées , la valeur par défaut, indique à l’analyseur d’interpréter les éléments contenus dans les balises du contrôle serveur en tant que contenu qui sera analysé avec un élément associé ControlBuilder , en tant que contrôles. Dans ce scénario, la ChildrenAsProperties propriété est false.

Pour plus d’informations sur l’utilisation d’attributs, consultez Attributs.

Voir aussi

• Attribute
• PersistChildrenAttribute
• extension des métadonnées à l’aide d’attributs