PersistChildrenAttribute 類別

定義

定義 ASP.NET 伺服器控制項使用的屬性 (Attribute),指出設計階段時伺服器控制項中包含的巢狀內容對應至控制項,或是伺服器控制項的屬性 (Property)。Defines an attribute that is used by ASP.NET server controls to indicate at design time whether nested content that is contained within a server control corresponds to controls or to properties of the server control. 無法繼承這個類別。This class cannot be inherited.

public ref class PersistChildrenAttribute sealed : Attribute
[System.AttributeUsage(System.AttributeTargets.Class)]
public sealed class PersistChildrenAttribute : Attribute
type PersistChildrenAttribute = class
    inherit Attribute
Public NotInheritable Class PersistChildrenAttribute
Inherits Attribute
繼承
PersistChildrenAttribute
屬性

範例

本節中的程式碼範例包含兩個部分。The code example in this section contains two parts. 第一個程式碼範例示範如何設定自訂控制項的中繼資料,以便在設計階段將其嵌套內容保存為控制項的屬性。The first code example demonstrates how to set the metadata of a custom control so that at design time, its nested content is persisted as properties of the control. 第二個程式碼範例示範如何使用 ASP.NET 網頁中的類別。The second code example demonstrates how to use classes in an ASP.NET page.

下列程式碼範例示範如何套用 PersistChildrenAttribute 屬性,如此一來,任何自訂伺服器控制項的嵌套控制項都不會保存為嵌套控制項。The following code example demonstrates how to apply the PersistChildrenAttribute attribute so that none of a custom server control's nested controls are persisted as nested controls. 名為 CollectionPropertyControl 的自訂伺服器控制項將 PersistChildrenAttribute 屬性設定為 false,以便新增的 Employee 物件會保存為嵌套元素。The custom server control named CollectionPropertyControl has the PersistChildrenAttribute attribute set to false so that the Employee objects that are added are persisted as nested elements.

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);
      }
   }
}
' 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.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

    
   Public Sub New(name As String, title As String, 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
         _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

 ' 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
 End Class
End Namespace ' PersistChildrenSampleVB

下列程式碼範例示範如何使用 ASP.NET 網頁中的 CollectionPropertyControlEmployee 類別。The following code example demonstrates how to use the CollectionPropertyControl and Employee classes in an ASP.NET page.

<%@ 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 xmlns="http://www.w3.org/1999/xhtml" >
<head 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="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 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:CollectionPropertyControl>
    </div>
    </form>
</body>
</html>

備註

PersistChildrenAttribute 會與 ParseChildrenAttribute 一起使用,以決定如何解讀控制項的嵌套內容。The PersistChildrenAttribute is used in combination with the ParseChildrenAttribute to determine how nested content of a control is interpreted. 如果 PersistChildrenAttributetruefalseParseChildrenAttribute,則包含在 ASP.NET 伺服器控制項內的嵌套內容會保存為控制項。If PersistChildrenAttribute is true and ParseChildrenAttribute is false, the nested content contained within an ASP.NET server control is persisted as controls. 如果 PersistChildrenAttributefalsetrueParseChildrenAttribute,則會將嵌套的內容保存為伺服器控制項的屬性。If PersistChildrenAttribute is false and ParseChildrenAttribute is true, the nested content is persisted as properties of the server control. 如需使用屬性的詳細資訊,請參閱屬性For more information about using attributes, see Attributes.

建構函式

PersistChildrenAttribute(Boolean)

使用布林值指出是否將巢狀內容保存為巢狀控制項,初始化 PersistChildrenAttribute 類別的新執行個體。Initializes a new instance of the PersistChildrenAttribute class using a Boolean value indicating whether to persist nested content as nested controls.

PersistChildrenAttribute(Boolean, Boolean)

使用兩個布林值,初始化 PersistChildrenAttribute 類別的新執行個體。Initializes a new instance of the PersistChildrenAttribute class using two Boolean values. 一個指出是否將巢狀內容保存為巢狀控制項,另一個指出是否使用自訂持續性方法。One indicating whether to persist nested content as nested controls and the other indicating whether to use a custom persistence method.

欄位

Default

指示預設的屬性狀態。Indicates the default attribute state. Default 欄位是唯讀的。The Default field is read-only.

No

表示設計階段時巢狀內容不應保存為巢狀控制項。Indicates that nested content should not persist as nested controls at design time. 此欄位為唯讀。This field is read-only.

Yes

表示設計階段時巢狀內容應保存為控制項。Indicates that nested content should persist as controls at design time. Yes 欄位是唯讀的。The Yes field is read-only.

屬性

Persist

取得值,指出設計階段時巢狀內容是否保存為巢狀控制項。Gets a value that indicates whether the nested content is persisted as nested controls at design time.

TypeId

在衍生類別中實作時,取得這個 Attribute 的唯一識別碼。When implemented in a derived class, gets a unique identifier for this Attribute.

(繼承來源 Attribute)
UsesCustomPersistence

取得值,指出設計階段時伺服器控制項是否提供巢狀控制項的自訂持續性。Gets a value indicating whether the server control provides custom persistence of nested controls at design time.

方法

Equals(Object)

判斷指定的物件是否等於目前的物件。Determines whether the specified object is equal to the current object.

GetHashCode()

做為 PersistChildrenAttribute 類別的雜湊函式。Serves as a hash function for the PersistChildrenAttribute class.

GetType()

取得目前執行個體的 TypeGets the Type of the current instance.

(繼承來源 Object)
IsDefaultAttribute()

傳回值,指出 PersistChildrenAttribute 類別目前執行個體的值是否為衍生類別的預設值。Returns a value indicating whether the value of the current instance of the PersistChildrenAttribute class is the default value of the derived class.

Match(Object)

在衍生類別中覆寫時,會傳回值,表示這個執行個體是否等於指定物件。When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.

(繼承來源 Attribute)
MemberwiseClone()

建立目前 Object 的淺層複製。Creates a shallow copy of the current Object.

(繼承來源 Object)
ToString()

傳回代表目前物件的字串。Returns a string that represents the current object.

(繼承來源 Object)

明確介面實作

_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

將一組名稱對應至一組對應的分派識別項 (Dispatch Identifier)。Maps a set of names to a corresponding set of dispatch identifiers.

(繼承來源 Attribute)
_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

擷取物件的類型資訊,可以用來取得介面的類型資訊。Retrieves the type information for an object, which can be used to get the type information for an interface.

(繼承來源 Attribute)
_Attribute.GetTypeInfoCount(UInt32)

擷取物件提供的類型資訊介面數目 (0 或 1)。Retrieves the number of type information interfaces that an object provides (either 0 or 1).

(繼承來源 Attribute)
_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

提供物件所公開的屬性和方法的存取權。Provides access to properties and methods exposed by an object.

(繼承來源 Attribute)

適用於

另請參閱