Binding EventHandler для пользовательского WebControl

Question

У меня есть пользовательский веб-элемент управления, который является производным от Panel. В моей ASPX разметкой для контроля, у меня есть public event EventHandler называется SubmitButtonClicked

<cc1:CreditCard ID="CustomCreditCardPopupPanel" runat="server" 
SubmitButtonClicked="CustomCreditCardPopupPanel_SubmitClick"> </cc1:CreditCard> 

Вот код для пользовательского веб-управления (сокращенные для ясности). Когда веб-элемент управления создается, EventHandler SubmitButtonClicked всегда имеет значение null. Как передать имя события, которое я хочу связать с Button под названием BtnSubmit?

[DefaultProperty("Text"), 
    AspNetHostingPermission(SecurityAction.Demand, 
    Level = AspNetHostingPermissionLevel.Minimal), 
    AspNetHostingPermission(SecurityAction.InheritanceDemand, 
    Level = AspNetHostingPermissionLevel.Minimal), 
    ToolboxData("<{0}:CreditCard runat=server></{0}:CreditCard>") 
] 
public class CreditCard: Panel { 

    public event EventHandler SubmitButtonClicked; 
    public Button BtnSubmit { get; set; } 

    protected override void OnPreRender(EventArgs e) { 
    base.OnPreRender(e); 
    this.BtnSubmit.Click += new EventHandler(SubmitButtonClicked); // SubmitButtonClicked is always null 
    } 

    protected void SubmitButtonClicked_Clicked(Object sender, EventArgs e) { 

    if (SubmitButtonClicked != null) { 

     SubmitButtonClicked(sender, e); 
    } 

} 

} 

Answer 1

Вы должны

this.BtnSubmit.Click += new EventHandler(SubmitButtonClicked_Clicked); 

А также, OnPreRender событие может быть слишком поздно. Возможно, вам нужно назначить событие кнопки в Init или Load event

Answer 2

Оказывается, что лучший способ справиться с тем, что я хочу сделать, - это получить мой класс из CompositeControl.

MSDN CompositeControl

Пример из Ссылка:

// Register.cs 
using System; 
using System.ComponentModel; 
using System.Drawing; 
using System.Security.Permissions; 
using System.Web; 
using System.Web.UI; 
using System.Web.UI.WebControls; 

namespace Samples.AspNet.CS.Controls 
{ 
    [ 
    AspNetHostingPermission(SecurityAction.Demand, 
     Level = AspNetHostingPermissionLevel.Minimal), 
    AspNetHostingPermission(SecurityAction.InheritanceDemand, 
     Level=AspNetHostingPermissionLevel.Minimal), 
    DefaultEvent("Submit"), 
    DefaultProperty("ButtonText"), 
    ToolboxData("<{0}:Register runat=\"server\"> </{0}:Register>"), 
    ] 
    public class Register : CompositeControl 
    { 
     private Button submitButton; 
     private TextBox nameTextBox; 
     private Label nameLabel; 
     private TextBox emailTextBox; 
     private Label emailLabel; 
     private RequiredFieldValidator emailValidator; 
     private RequiredFieldValidator nameValidator; 

     private static readonly object EventSubmitKey = 
      new object(); 

     // The following properties are delegated to 
     // child controls. 
     [ 
     Bindable(true), 
     Category("Appearance"), 
     DefaultValue(""), 
     Description("The text to display on the button.") 
     ] 
     public string ButtonText 
     { 
      get 
      { 
       EnsureChildControls(); 
       return submitButton.Text; 
      } 
      set 
      { 
       EnsureChildControls(); 
       submitButton.Text = value; 
      } 
     } 

     [ 
     Bindable(true), 
     Category("Default"), 
     DefaultValue(""), 
     Description("The user name.") 
     ] 
     public string Name 
     { 
      get 
      { 
       EnsureChildControls(); 
       return nameTextBox.Text; 
      } 
      set 
      { 
       EnsureChildControls(); 
       nameTextBox.Text = value; 
      } 
     } 

     [ 
     Bindable(true), 
     Category("Appearance"), 
     DefaultValue(""), 
     Description(
      "Error message for the name validator.") 
     ] 
     public string NameErrorMessage 
     { 
      get 
      { 
       EnsureChildControls(); 
       return nameValidator.ErrorMessage; 
      } 
      set 
      { 
       EnsureChildControls(); 
       nameValidator.ErrorMessage = value; 
       nameValidator.ToolTip = value; 
      } 
     } 

     [ 
     Bindable(true), 
     Category("Appearance"), 
     DefaultValue(""), 
     Description("The text for the name label.") 
     ] 
     public string NameLabelText 
     { 
      get 
      { 
       EnsureChildControls(); 
       return nameLabel.Text; 
      } 
      set 
      { 
       EnsureChildControls(); 
       nameLabel.Text = value; 
      } 
     } 

     [ 
     Bindable(true), 
     Category("Default"), 
     DefaultValue(""), 
     Description("The e-mail address.") 
     ] 
     public string Email 
     { 
      get 
      { 
       EnsureChildControls(); 
       return emailTextBox.Text; 
      } 
      set 
      { 
       EnsureChildControls(); 
       emailTextBox.Text = value; 
      } 
     } 

     [ 
     Bindable(true), 
     Category("Appearance"), 
     DefaultValue(""), 
     Description(
      "Error message for the e-mail validator.") 
     ] 
     public string EmailErrorMessage 
     { 
      get 
      { 
       EnsureChildControls(); 
       return emailValidator.ErrorMessage; 
      } 
      set 
      { 
       EnsureChildControls(); 
       emailValidator.ErrorMessage = value; 
       emailValidator.ToolTip = value; 
      } 
     } 

     [ 
     Bindable(true), 
     Category("Appearance"), 
     DefaultValue(""), 
     Description("The text for the e-mail label.") 
     ] 
     public string EmailLabelText 
     { 
      get 
      { 
       EnsureChildControls(); 
       return emailLabel.Text; 
      } 
      set 
      { 
       EnsureChildControls(); 
       emailLabel.Text = value; 

      } 
     } 

     // The Submit event. 
     [ 
     Category("Action"), 
     Description("Raised when the user clicks the button.") 
     ] 
     public event EventHandler Submit 
     { 
      add 
      { 
       Events.AddHandler(EventSubmitKey, value); 
      } 
      remove 
      { 
       Events.RemoveHandler(EventSubmitKey, value); 
      } 
     } 

     // The method that raises the Submit event. 
     protected virtual void OnSubmit(EventArgs e) 
     { 
      EventHandler SubmitHandler = 
       (EventHandler)Events[EventSubmitKey]; 
      if (SubmitHandler != null) 
      { 
       SubmitHandler(this, e); 
      } 
     } 

     // Handles the Click event of the Button and raises 
     // the Submit event. 
     private void _button_Click(object source, EventArgs e) 
     { 
      OnSubmit(EventArgs.Empty); 
     } 

     protected override void RecreateChildControls() 
     { 
      EnsureChildControls(); 
     } 


     protected override void CreateChildControls() 
     { 
      Controls.Clear(); 

      nameLabel = new Label(); 

      nameTextBox = new TextBox(); 
      nameTextBox.ID = "nameTextBox"; 

      nameValidator = new RequiredFieldValidator(); 
      nameValidator.ID = "validator1"; 
      nameValidator.ControlToValidate = nameTextBox.ID; 
      nameValidator.Text = "Failed validation."; 
      nameValidator.Display = ValidatorDisplay.Static; 

      emailLabel = new Label(); 

      emailTextBox = new TextBox(); 
      emailTextBox.ID = "emailTextBox"; 

      emailValidator = new RequiredFieldValidator(); 
      emailValidator.ID = "validator2"; 
      emailValidator.ControlToValidate = 
       emailTextBox.ID; 
      emailValidator.Text = "Failed validation."; 
      emailValidator.Display = ValidatorDisplay.Static; 

      submitButton = new Button(); 
      submitButton.ID = "button1"; 
      submitButton.Click 
       += new EventHandler(_button_Click); 

      this.Controls.Add(nameLabel); 
      this.Controls.Add(nameTextBox); 
      this.Controls.Add(nameValidator); 
      this.Controls.Add(emailLabel); 
      this.Controls.Add(emailTextBox); 
      this.Controls.Add(emailValidator); 
      this.Controls.Add(submitButton); 
     } 


     protected override void Render(HtmlTextWriter writer) 
     { 
      AddAttributesToRender(writer); 

      writer.AddAttribute(
       HtmlTextWriterAttribute.Cellpadding, 
       "1", false); 
      writer.RenderBeginTag(HtmlTextWriterTag.Table); 

      writer.RenderBeginTag(HtmlTextWriterTag.Tr); 
      writer.RenderBeginTag(HtmlTextWriterTag.Td); 
      nameLabel.RenderControl(writer); 
      writer.RenderEndTag(); 
      writer.RenderBeginTag(HtmlTextWriterTag.Td); 
      nameTextBox.RenderControl(writer); 
      writer.RenderEndTag(); 
      writer.RenderBeginTag(HtmlTextWriterTag.Td); 
      nameValidator.RenderControl(writer); 
      writer.RenderEndTag(); 
      writer.RenderEndTag(); 

      writer.RenderBeginTag(HtmlTextWriterTag.Tr); 
      writer.RenderBeginTag(HtmlTextWriterTag.Td); 
      emailLabel.RenderControl(writer); 
      writer.RenderEndTag(); 
      writer.RenderBeginTag(HtmlTextWriterTag.Td); 
      emailTextBox.RenderControl(writer); 
      writer.RenderEndTag(); 
      writer.RenderBeginTag(HtmlTextWriterTag.Td); 
      emailValidator.RenderControl(writer); 
      writer.RenderEndTag(); 
      writer.RenderEndTag(); 

      writer.RenderBeginTag(HtmlTextWriterTag.Tr); 
      writer.AddAttribute(
       HtmlTextWriterAttribute.Colspan, 
       "2", false); 
      writer.AddAttribute(
       HtmlTextWriterAttribute.Align, 
       "right", false); 
      writer.RenderBeginTag(HtmlTextWriterTag.Td); 
      submitButton.RenderControl(writer); 
      writer.RenderEndTag(); 
      writer.RenderBeginTag(HtmlTextWriterTag.Td); 
      writer.Write("&nbsp;"); 
      writer.RenderEndTag(); 
      writer.RenderEndTag(); 

      writer.RenderEndTag(); 
     } 
    } 
}