PersistChildrenAttribute クラスとは何？わかりやすく解説 Weblio辞書

.NET Framework クラスライブラリリファレンス

索引トップ用語の索引ランキング

PersistChildrenAttribute クラス

デザイン時に、サーバーコントロール内に含まれている入れ子になった内容がコントロールなのかサーバーコントロールのプロパティなのか示す、ASP.NET サーバーコントロールによって使用される属性を定義します。このクラスは継承できません。

名前空間: System.Web.UI
アセンブリ: System.Web (system.web.dll 内)
構文

Visual Basic (宣言)

<AttributeUsageAttribute(AttributeTargets.Class)> _
Public NotInheritable Class
 PersistChildrenAttribute
    Inherits Attribute

Visual Basic (使用法)

Dim instance As PersistChildrenAttribute

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

C++

[AttributeUsageAttribute(AttributeTargets::Class)] 
public ref class PersistChildrenAttribute sealed
 : public Attribute

/** @attribute AttributeUsageAttribute(AttributeTargets.Class) */ 
public final class PersistChildrenAttribute
 extends Attribute

JScript

AttributeUsageAttribute(AttributeTargets.Class) 
public final class PersistChildrenAttribute
 extends Attribute

解説

PersistChildrenAttribute は、コントロールの入れ子になった内容の解釈方法を示す ParseChildrenAttribute と組み合わせて使用されます。PersistChildrenAttribute が true で、ParseChildrenAttribute が false の場合、ASP.NET サーバーコントロール内の入れ子になった内容はコントロールとして保持されます。PersistChildrenAttribute が false で、ParseChildrenAttribute が true の場合、入れ子になった内容はサーバーコントロールのプロパティとして保持されます。属性の使用方法については、「属性を使用したメタデータの拡張」を参照してください。

Topic	Location
チュートリアル : カスタムサーバーコントロールの開発と使用	ASP.NET コントロールの作成

使用例

このセクションには、2 つのコード例が含まれています。最初のコード例では、デザイン時に、入れ子になった内容がコントロールのプロパティとして保持されるようにカスタムコントロールのメタデータを設定する方法を示しています。2 番目のコード例では、ASP.NET ページでクラスを使用する方法を示します。

次のコード例では、カスタムサーバーコントロールの入れ子になった内容を、入れ子になったコントロールとして保持しないように PersistChildrenAttribute 属性を適用する方法を示しています。CollectionPropertyControl という名前のカスタムサーバーコントロールの PersistChildrenAttribute 属性は false に設定され、追加される Employee オブジェクトは入れ子になった要素として保持されます。

Visual Basic

' Create a namespace that defines two classes, one a custom control,
 Employee,
' which is created for every instance of a child element with its name
' declared in a page associated with this namespace, the other, Employees
,
' which contains these child elements.
Imports System
Imports System.Collections
Imports System.Drawing
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Security.Permissions

Namespace PersistChildrenSampleVB

' Create a class that will be rendered as a child of the control
' that has the ParseChildren attribute applied to it.
 <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 'New

    
   Public Sub New(name As
 String, title As String,
 employeeAlias As String)
      Me._name = name
      Me._title = title
      Me._alias = employeeAlias
   End Sub 'New
   
   Public Property Name() As
 String
      Get
         Return _name
      End Get
      Set
         _name = value
      End Set
   End Property
   
   
   Public Property Title() As
 String
      Get
         Return _title
      End Get
      Set
         _title = value
      End Set
   End Property
   
   
   Public Property [Alias]() As
 String
      Get
         Return _alias
      End Get
      Set
         _alias = value
      End Set
   End Property
End Class 'Employee

 ' Use the PersistChildren attribute to set the Persist
 ' property to false so that none of this class's
 ' child controls will be persisted as controls. They will
 ' be persisted only as child elements of this class.
 ' If you set the PersistChildren attribute to true, or if you
 ' do not include this attribute when you create a control,
 ' the child controls will be persisted as controls.
 <PersistChildren(False)>  _
 <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
         _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 = Color.Beige
      label.ForeColor = 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 = Color.Beige
      table.ForeColor = 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 'CreateChildControls
 
 End Class 'CollectionPropertyControl
End Namespace ' PersistChildrenSampleVB

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

namespace PersistChildrenSamples
{
   // 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 PersistChildren attribute to set the Persist
   // property to false so that none of this class's
   // child controls will be persisted as controls. They will
   // be persisted only as child elements of this class.
   // If you set the PersistChildren attribute to true, or if you
   // do not include this attribute when you create a control,
   // the child controls will be persisted as controls.   
   [PersistChildren(false)]
   [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 = Color.Beige;
         label.ForeColor = 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 = Color.Beige;
         table.ForeColor = 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);
         
      }
   }
}

次のコード例では、CollectionPropertyControl クラスと Employee クラスを ASP.NET ページで使用する方法を示しています。

Visual Basic

<%@ Page Language="VB" %>
<%@ Register TagPrefix="AspSample" Assembly="Samples.AspNet.VB.Controls"
 Namespace="PersistChildrenSampleVB"
 %>


<!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)

    ' Create two new employees and add them to the custom control.
    Dim e1 As New Employee("Employee
 1", "Title 1", "Alias
 1")
    Dim e2 As New Employee("Employee
 2", "Title 2", "Alias
 2")
    CollectionPropertyControl1.Employees.Add(e1)
    CollectionPropertyControl1.Employees.Add(e2)

    ' Verify attribute values.
    Dim p As PersistChildrenAttribute = _
    Attribute.GetCustomAttribute(GetType(CollectionPropertyControl),
 _
    GetType(PersistChildrenAttribute))

    Dim sb As New StringBuilder()
    sb.Append("The Persist property is " & p.Persist.ToString()
 & "<br>")
    sb.Append("The UseCustomPersistence property is "
 & p.UsesCustomPersistence.ToString() & "<br>")
    sb.Append("The IsDefault method returns " &
 p.IsDefaultAttribute().ToString())
    Message.Text = sb.ToString()

  End Sub
  
</script>


<html  >
<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:CollectionPropertyControl>
    </div>
    </form>
</body>
</html>

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

<!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)
  {

    // Create two new employees and add them to the custom control.
    Employee e1 = new Employee("Employee 1", "Title
 1", "Alias 1");
    Employee e2 = new Employee("Employee 2", "Title
 2", "Alias 2");
    CollectionPropertyControl1.Employees.Add(e1);
    CollectionPropertyControl1.Employees.Add(e2);

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

    StringBuilder sb = new StringBuilder();
    sb.Append("The Persist property is " + p.Persist.ToString() + "<br>");
    sb.Append("The UseCustomPersistence property is " + p.UsesCustomPersistence.ToString()
 + "<br>");
    sb.Append("The IsDefault method returns " + p.IsDefaultAttribute().ToString());
    Message.Text = sb.ToString();
    
  }
</script>

<html  >
<head runat="server">
    <title>PersistChildrenAttribute</title>
</head>
<body>
    <form runat="server">
    <div>
      <asp:Label ID="Message"
                 runat="server"/>
      <AspSample:CollectionPropertyControl id="CollectionPropertyControl1"
 
                                           runat="server">
      </AspSample:CollectionPropertyControl>
    </div>
    </form>
</body>
</html>