ParseChildrenAttribute Classe

Definição

Define um atributo de metadados que pode ser usado ao desenvolver controles de servidor ASP.NET.Defines a metadata attribute that you can use when developing ASP.NET server controls. Use a classe ParseChildrenAttribute para indicar como o analisador de página deve tratar conteúdo aninhado dentro de uma marca de controle de servidor declarada em uma página.Use the ParseChildrenAttribute class to indicate how the page parser should treat content nested inside a server control tag declared on a page. Essa classe não pode ser herdada.This class cannot be inherited.

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
Herança
ParseChildrenAttribute
Atributos

Exemplos

O exemplo de código nesta seção contém duas partes.The code example in this section contains two parts. O primeiro exemplo de código demonstra como definir propriedades para a ParseChildrenAttribute classe.The first code example demonstrates how to set properties for the ParseChildrenAttribute class. O segundo exemplo de código demonstra como usar classes em uma página ASP.NET.The second code example demonstrates how to use classes in an ASP.NET page.

O exemplo de código a seguir demonstra como definir o ParseChildrenAttribute objeto de um controle de servidor personalizado chamado CollectionPropertyControl .The following code example demonstrates how to set the ParseChildrenAttribute object of a custom server control named CollectionPropertyControl. O ParseChildrenAttribute define a ChildrenAsProperties propriedade como true e a DefaultProperty propriedade para a Employee classe.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);
      }
   }
}
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

O exemplo de código a seguir demonstra como usar CollectionPropertyControl as Employee classes e em uma página ASP.net.The following code example demonstrates how to use the CollectionPropertyControl and Employee classes in an ASP.NET page. As instâncias da Employee classe são adicionadas declarativamente.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>
<%@ 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>

Comentários

A ParseChildrenAttribute classe permite que você especifique a lógica de análise para um controle de servidor personalizado marcando o controle de servidor com o ParseChildrenAttribute atributo de metadados.The ParseChildrenAttribute class allows you to specify parsing logic for a custom server control by marking the server control with the ParseChildrenAttribute metadata attribute.

Marcar o controle de servidor com o atributo de metadados ParseChildren(true) instrui o analisador a interpretar os elementos contidos nas marcas do controle de servidor como propriedades.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. Nesse cenário, a ChildrenAsProperties propriedade é true .In this scenario, the ChildrenAsProperties property is true.

Marcar o controle de servidor com o atributo de metadados ParseChildren(true,"<Default Property>") define a DefaultProperty propriedade como o nome da propriedade que é passada para o atributo.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.

Marcar o controle de servidor com o atributo de metadados ParseChildren(false) , o valor padrão, instrui o analisador a interpretar os elementos contidos nas marcas do controle de servidor como conteúdo que será analisado com um associado ControlBuilder , como controles.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. Nesse cenário, a ChildrenAsProperties propriedade é false .In this scenario, the ChildrenAsProperties property is false.

Para obter informações sobre como usar atributos, consulte atributos.For information about using attributes, see Attributes.

Construtores

ParseChildrenAttribute()

Inicializa uma nova instância da classe ParseChildrenAttribute.Initializes a new instance of the ParseChildrenAttribute class.

ParseChildrenAttribute(Boolean)

Inicializa uma nova instância da classe ParseChildrenAttribute usando a propriedade ChildrenAsProperties para determinar se os elementos que estão contidos em um controle de servidor são analisados como propriedades do controle do servidor.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.

ParseChildrenAttribute(Boolean, String)

Inicializa uma nova instância da classe ParseChildrenAttribute usando os parâmetros childrenAsProperties e defaultProperty.Initializes a new instance of the ParseChildrenAttribute class using the childrenAsProperties and defaultProperty parameters.

ParseChildrenAttribute(Type)

Inicializa uma nova instância da classe ParseChildrenAttribute usando a propriedade ChildControlType para determinar quais elementos contidos em um controle de servidor são analisados como controles.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.

Campos

Default

Define o valor padrão para a classe ParseChildrenAttribute.Defines the default value for the ParseChildrenAttribute class. Este campo é somente leitura.This field is read-only.

ParseAsChildren

Indica que o conteúdo aninhado contido no controle de servidor é analisado como controles.Indicates that the nested content that is contained within the server control is parsed as controls.

ParseAsProperties

Indica que o conteúdo aninhado dentro de um controle de servidor é analisado como propriedades do controle.Indicates that the nested content that is contained within a server control is parsed as properties of the control.

Propriedades

ChildControlType

Obtém um valor que indica o tipo permitido de um controle.Gets a value indicating the allowed type of a control.

ChildrenAsProperties

Obtém ou define um valor que indica se é preciso analisar os elementos contidos em um controle de servidor como propriedades.Gets or sets a value indicating whether to parse the elements that are contained within a server control as properties.

DefaultProperty

Obtém ou define a propriedade padrão para o controle de servidor no qual os elementos são analisados.Gets or sets the default property for the server control into which the elements are parsed.

TypeId

Quando implementado em uma classe derivada, obtém um identificador exclusivo para este Attribute.When implemented in a derived class, gets a unique identifier for this Attribute.

(Herdado de Attribute)

Métodos

Equals(Object)

Determina se o objeto especificado é igual ao objeto atual.Determines whether the specified object is equal to the current object.

GetHashCode()

Serve como uma função hash para o objeto ParseChildrenAttribute.Serves as a hash function for the ParseChildrenAttribute object.

GetType()

Obtém o Type da instância atual.Gets the Type of the current instance.

(Herdado de Object)
IsDefaultAttribute()

Retorna um valor que indica se o valor da instância atual da classe ParseChildrenAttribute é o valor padrão da classe derivada.Returns a value indicating whether the value of the current instance of the ParseChildrenAttribute class is the default value of the derived class.

Match(Object)

Quando substituído em uma classe derivada, retorna um valor que indica se essa instância é igual a um objeto especificado.When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.

(Herdado de Attribute)
MemberwiseClone()

Cria uma cópia superficial do Object atual.Creates a shallow copy of the current Object.

(Herdado de Object)
ToString()

Retorna uma cadeia de caracteres que representa o objeto atual.Returns a string that represents the current object.

(Herdado de Object)

Implantações explícitas de interface

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

Mapeia um conjunto de nomes para um conjunto correspondente de identificadores de expedição.Maps a set of names to a corresponding set of dispatch identifiers.

(Herdado de Attribute)
_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Recupera as informações de tipo para um objeto, que pode ser usado para obter as informações de tipo para uma interface.Retrieves the type information for an object, which can be used to get the type information for an interface.

(Herdado de Attribute)
_Attribute.GetTypeInfoCount(UInt32)

Retorna o número de interfaces de informações do tipo que um objeto fornece (0 ou 1).Retrieves the number of type information interfaces that an object provides (either 0 or 1).

(Herdado de Attribute)
_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Fornece acesso a propriedades e métodos expostos por um objeto.Provides access to properties and methods exposed by an object.

(Herdado de Attribute)

Aplica-se a

Confira também