ASP.Net 自定义服务器控件不触发自定义事件

Question

我创建了一个自定义服务器控件。它看起来很棒，渲染的 HTML 也符合它应有的样子。我最初让它扩展了 ControlContainer，现在它扩展了 WebControl（两者的行为相同）。它有两个属性：ImageUrl 和 Text。本质上，它将呈现一个通用 HTML 标签，其中包含一个 和 标签。

我的问题是暴露的 ServerClick 事件（我相信由 NamingContainer 提供）似乎没有触发。如果我添加任何 ASP 按钮（链接、图像或常规）并关联到该 Click 事件，它就会触发，但当然我还有额外的渲染内容。它成功运行 javascript 并执行 __dopostback 调用。但它不能看到给定的控件 ID 或其他内容，因为该事件永远不会被触发。

using System;
using System.ComponentModel;
using System.Drawing.Design;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;

namespace PLSO.Info.Web.UI {

[DefaultEvent("Submit")]
[DefaultProperty("Text")]
[ToolboxData("<{0}:ComboButton runat=\"server\"> </{0}:ComboButton>")]
public class ComboButton : WebControl {

    private HtmlImage imageControl;
    private HtmlGenericControl spanControl;

    private static readonly object EventSubmitKey = new object();

    [Bindable(true)]
    [Category("Appearance")]
    [DefaultValue("")]
    [Description("The text to display on the button.")]
    public string Text {
        get { return ViewState["NewText"] as string; }
        set { ViewState["NewText"] = value; }
    }

    [DefaultValue("")]
    [Bindable(true)]
    [Category("Appearance")]
    [UrlProperty()]
    [Editor("System.Web.UI.Design.ImageUrlEditor, System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", typeof(UITypeEditor))]
    public string ImageUrl {
        get {
            EnsureChildControls();
            return this.imageControl.Src;
        }
        set {
            EnsureChildControls();
            this.imageControl.Src = value;
        }
    } // ImageUrl - Property

    public override string CssClass {
        get { return ViewState["CssClass"] as string; }
        set { ViewState["CssClass"] = value; }
    }

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

    protected virtual void OnSubmit(EventArgs e) {
        EventHandler SubmitHandler = (EventHandler)Events[EventSubmitKey];

        if (SubmitHandler != null)
            SubmitHandler(this, e);
    }

    void ComboButton_Submit(object sender, EventArgs e) {
        OnSubmit(EventArgs.Empty);
    }

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

        imageControl = new HtmlImage();
        imageControl.Src = this.ImageUrl;
        imageControl.Alt = this.Text;
        this.Controls.Add(imageControl);

        spanControl = new HtmlGenericControl("span");
        spanControl.InnerText = this.Text;
        this.Controls.Add(spanControl);

        this.Submit += new EventHandler(ComboButton_Submit);

        ChildControlsCreated = true;
    }

    protected override void Render(HtmlTextWriter writer) {
        PostBackOptions pbo = new PostBackOptions(this);

        AddAttributesToRender(writer);
        writer.AddAttribute(HtmlTextWriterAttribute.Class, this.CssClass);
        writer.AddAttribute("onclick", string.Format("javascript:{0}", Page.ClientScript.GetPostBackEventReference(pbo)));
        writer.RenderBeginTag(HtmlTextWriterTag.Button);
        imageControl.RenderControl(writer);
        spanControl.RenderControl(writer);
        writer.RenderEndTag();
    }
    }
}

这是我的标记。我放入此控件，然后放入常规 ASP:Button。那个常规按钮的事件被击中！不是我的。

<ucs:ComboButton ID="btnT4" runat="server" Text="Please" CssClass="PButtonCombo" ImageUrl="~/Styles/icons/edit-find.png" OnSubmit="btnT4_Submit" />
<asp:Button ID="btnT5" runat="server" Text="TEST" onclick="btnT5_Click" UseSubmitBehavior="False" />

这是渲染的 HTML：

<button id="MainContent_btnT4" class="PButtonCombo" onclick="javascript:__doPostBack(&#39;ctl00$MainContent$btnT4&#39;,&#39;&#39;)"><img src="../Styles/icons/edit-find.png" alt="Please" /><span>Please</span></button>
<input type="button" name="ctl00$MainContent$btnT5" value="TEST" onclick="javascript:__doPostBack(&#39;ctl00$MainContent$btnT5&#39;,&#39;&#39;)" id="MainContent_btnT5" />

我必须相信我已经很接近了，但只是缺少一些东西。今天调整了几个小时，请帮忙！

编辑：

感谢@James的回答，我所做的就是将以下内容添加到上面示例的顶部。它成功了，但现在发射了两次。不知道为什么？这就是我当前的问题：

public class ComboButton : WebControl, IPostBackEventHandler {

    public void RaisePostBackEvent(string eventArgument) {
        OnClick(new EventArgs());
    }

    [Category("Action")]
    [Description("Raised when the user clicks the button.")]
    public event EventHandler Click;

    protected virtual void OnClick(EventArgs e) {
        if (Click != null)
            Click(this, e);
    }

编辑 2 == 解决方案

using System.ComponentModel;
using System.Drawing.Design;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;

namespace PLSO.Info.Web.UI {

[DefaultEvent("Submit")]
[DefaultProperty("Text")]
[ToolboxData("<{0}:ComboButton runat=\"server\"> </{0}:ComboButton>")]
public class ComboButton : Button {

    private HtmlImage imageControl;
    private HtmlGenericControl spanControl;

    [DefaultValue("")]
    [Bindable(true)]
    [Category("Appearance")]
    [UrlProperty()]
    [Editor("System.Web.UI.Design.ImageUrlEditor, System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", typeof(UITypeEditor))]
    public string ImageUrl {
        get {
            EnsureChildControls();
            return this.imageControl.Src;
        }
        set {
            EnsureChildControls();
            this.imageControl.Src = value;
        }
    } // ImageUrl - Property

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

        imageControl = new HtmlImage();
        imageControl.Src = this.ImageUrl;
        imageControl.Alt = this.Text;
        this.Controls.Add(imageControl);

        spanControl = new HtmlGenericControl("span");
        spanControl.InnerText = this.Text;
        this.Controls.Add(spanControl);

        ChildControlsCreated = true;
    } // CreateChildControls - Method - Override

    protected override void Render(HtmlTextWriter writer) {
        PostBackOptions pbo = new PostBackOptions(this);

        AddAttributesToRender(writer);
        writer.RenderBeginTag(HtmlTextWriterTag.Button);
        imageControl.RenderControl(writer);
        spanControl.RenderControl(writer);
        writer.RenderEndTag();
    } // Render - Event - Override
  }
}

Answer 1

尝试实现 IPostBackEventHandler 接口：

public class ComboButton : WebControl, IPostBackEventHandler  
{
    public void RaisePostBackEvent(string eventArgument)
    {
        OnSubmit(EventArgs.Empty); 
    }
}

这里有一篇文章解释了 IPostBackEventHandler 接口的实现：
http://msdn.microsoft.com/en-us /library/system.web.ui.ipostbackeventhandler.aspx

编辑

如果您的事件在某种程度上依赖于数据，则需要实现 IPostBackDataHandler 接口。例如，您可以使用 IPostBackDataHandler 接口来触发 TextBox 的 OnTextChanged 事件：

public class ComboButton : WebControl, IPostBackDataHandler  
{
    public virtual bool LoadPostData(string postDataKey, NameValueCollection postCollection)
    {
        return true;
    }

    public virtual void RaisePostDataChangedEvent()
    {

    }
}

以下文章介绍了 IPostBackDataHandler 接口的实现:
http://msdn.microsoft.com/en-us /library/system.web.ui.ipostbackdatahandler.aspx

Answer 2

您需要查看 IPostBackEventHandler

如果您没有在控件中实现此接口，ASP.net 引擎将不会将事件转发到您的控件。