Ejemplo de control basado en plantilla

En el siguiente ejemplo de control basado en plantilla, TemplatedFirstControl, tiene una propiedad FirstTemplate, del tipo ITemplate, y dos propiedades, Text y DateTime, que contienen los datos para el control. TemplatedFirstControl convierte el ejemplo que aparece en Desarrollar un control de servidor ASP.NET sencillo en un control basado en plantilla permitiendo así a un programador de páginas personalizar su presentación.

Para generar el ejemplo, vea las instrucciones en Ejemplos de control de servidor.

using System;
using System.Web;
using System.Web.UI;

namespace CustomControls
{
    [
    ParseChildren(true)
    ]
      public class TemplatedFirstControl : Control, INamingContainer
      {
            private ITemplate firstTemplate;
            private String text = null;
            private Control myTemplateContainer;
            
        protected override void OnDataBinding(EventArgs e) {
            EnsureChildControls();
            base.OnDataBinding(e);
        }


            [TemplateContainer(typeof(FirstTemplateContainer))]
                  
                  public ITemplate FirstTemplate
            {
                  get 
                  {
                        return firstTemplate;
                  }
                  set
                  {
                        firstTemplate = value;
                  }
            }
            
            public String Text
            {
                  get 
                  {
                        return text;
                  }
                  set
                  {
                        text = value;
                  }
            }
            
            public String DateTime
            {
                  get 
                  {
                        return System.DateTime.Now.ToLongTimeString();
                  }
                  
            }
            
            public Control MyTemplateContainer
            {
                  get
                  {
                        return myTemplateContainer;
                  }
            }
            
            protected override void CreateChildControls ()
                  
            {
                  if (FirstTemplate != null)
                  {
                        myTemplateContainer = new FirstTemplateContainer(this);
                        FirstTemplate.InstantiateIn(myTemplateContainer);
                        Controls.Add(myTemplateContainer);
                  }
                  else
                  {
                        Controls.Add(new LiteralControl(Text + " " + DateTime));
                  }
            }
            
      }
}
[Visual Basic]
Option Explicit
Option Strict

Imports System
Imports System.Web
Imports System.Web.UI

Namespace CustomControls
   <ParseChildren(True)> _
   Public Class TemplatedFirstControl
      Inherits Control
      Implements INamingContainer
      Private _firstTemplate As ITemplate
      Private _text As String = Nothing
      Private _myTemplateContainer As Control
      
      Protected Overrides Sub OnDataBinding(e As EventArgs)
         EnsureChildControls()
         MyBase.OnDataBinding(e)
      End Sub    
      
      <TemplateContainer(GetType(FirstTemplateContainer))> _
      Public Property FirstTemplate() As ITemplate
         Get
            Return _firstTemplate
         End Get
         Set
            _firstTemplate = value
         End Set
      End Property
      
      Public Property Text() As String
         Get
            Return _text
         End Get
         Set
            _text = value
         End Set
      End Property
      
      
      Public ReadOnly Property DateTime() As String
         Get
            Return System.DateTime.Now.ToLongTimeString()
         End Get
      End Property 
      
      
      Public ReadOnly Property MyTemplateContainer() As Control
         Get
            Return _myTemplateContainer
         End Get
      End Property
      
      
      Protected Overrides Sub CreateChildControls()
         
         If Not (FirstTemplate Is Nothing) Then
            _myTemplateContainer = New FirstTemplateContainer(Me)
            FirstTemplate.InstantiateIn(_myTemplateContainer)
            Controls.Add(_myTemplateContainer)
         Else
            Controls.Add(New LiteralControl(Text + " " + DateTime))
         End If
      End Sub
   End Class 
End Namespace

    

El siguiente control es el contenedor de la plantilla.

using System;
using System.Web;
using System.Web.UI;

namespace CustomControls
{
public class FirstTemplateContainer : Control, INamingContainer
      {
            private TemplatedFirstControl parent;
            public FirstTemplateContainer(TemplatedFirstControl parent)
            {
                  this.parent = parent;
            }
            
            public String Text
            {
                  get
                  {
                        return parent.Text;
                  }
            }
            public String DateTime
            {
                  get 
                  {
                        return parent.DateTime;
                  }
                  
            }
      }
}
[Visual Basic]
Option Explicit
Option Strict

Imports System
Imports System.Web
Imports System.Web.UI

Namespace CustomControls
   Public Class FirstTemplateContainer
      Inherits Control
      Implements INamingContainer
      Private _parent As TemplatedFirstControl
      
      Public Sub New(parent As TemplatedFirstControl)
         Me._parent = parent
      End Sub
      
      Public ReadOnly Property Text() As [String]
         Get
            Return _parent.Text
         End Get
      End Property
      
      Public ReadOnly Property DateTime() As [String]
         Get
            Return _parent.DateTime
         End Get
      End Property 
   End Class
End Namespace

Utilizar el control basado en plantilla en una página

En la siguiente página ASP.NET se utiliza el control basado en plantilla que se definió en el ejemplo anterior. Primero se utiliza el control con dos plantillas distintas y luego sin plantilla.

<%@ Register TagPrefix="Custom" Namespace="CustomControls" Assembly = "CustomControls" %>

<script runat=server language="VB">
   Sub Page_Load()
      First.DataBind()
      Second.DataBind()
   End Sub
</script>

<html>

   <body>
      
      <form  runat=server>
                  
          Here is a custom templated server control:<br><br>
          <Custom:TemplatedFirstControl id = "First" Text= "The time on the server is "  runat=server>                         
          <FirstTemplate>
          <h3><font face="Verdana" color = "red"><%# Container.Text %> <%# Container.DateTime %>
          </font></h3>
          </FirstTemplate>      
        </Custom:TemplatedFirstControl>
          
          Here is the templated server control with a different template:<br><br>
          <Custom:TemplatedFirstControl id = "Second" Text= "The time on the server is "  runat=server>                         
          <FirstTemplate>
          <h1><font face="Arial" color = "Purple"><%# Container.Text %> <%# Container.DateTime %>
          </font></h1>
          </FirstTemplate>     
        </Custom:TemplatedFirstControl>
           
           Here is the templated server control without a template:<br><br>
          <Custom:TemplatedFirstControl id = "Third" Text= "The time on the server is "  runat=server/>
                               
      </form>

   </body>

</html>

Vea también

Desarrollar un control enlazado a datos a partir de plantillas