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我将 RadioButtonList 控件子类化,以便创建一个控件适配器,它可以完全按照我想要的方式输出 HTML(这是我第一次编写适配器)。

我面临的问题是在访问“SelectedValue”属性时,我总是得到一个空字符串。如果我切换到超类,我会得到正确的值,所以我真的很困惑......我在这里错过了什么?

我的子类再简单不过了:

namespace Internet.Webapp.Controls
{
    public class RadioButtonList : System.Web.UI.WebControls.RadioButtonList
    {
    }
}

我的适配器也很简单:

public class RadioButtonListAdapter : System.Web.UI.Adapters.ControlAdapter
{
    // Return a strongly-typed reference
    public new Internet.Webapp.Controls.RadioButtonList Control
    {
        get
        {
            return (Internet.Webapp.Controls.RadioButtonList) base.Control;
        }
    }

    protected override void Render(HtmlTextWriter writer)
    {
        RadioButtonList radioButtonList = Control;

        writer.WriteBeginTag("div");
        writer.WriteAttribute("id", radioButtonList.ClientID);
        writer.Write(HtmlTextWriter.TagRightChar);

        var counter = 0;
        foreach (ListItem item in radioButtonList.Items)
        {
            writer.WriteFullBeginTag("div");

            var itemId = radioButtonList.ClientID + "_" + counter++;

            writer.WriteBeginTag("label");

            writer.WriteAttribute("for", itemId);

            writer.WriteAttribute("value", item.Text); 

            writer.WriteAttribute("class", "long");

            writer.Write(HtmlTextWriter.TagRightChar);

            writer.WriteBeginTag("input");

            writer.WriteAttribute("type", "radio");

            writer.WriteAttribute("id", itemId);

            writer.WriteAttribute("name", radioButtonList.UniqueID);

            writer.Write(HtmlTextWriter.TagRightChar);

            writer.WriteEndTag("input");

            writer.Write(item.Text);

            writer.WriteEndTag("label");

            writer.WriteEndTag("div");
        }
        writer.WriteEndTag("div");
    }
}

填充单选按钮列表的代码如下:

var radioButtonList = new Controls.RadioButtonList();

optionsList.ForEach(option => radioButtonList.Items.Add(option));

和生成的html:

  <div id="ctl00_MainSection_CordaanForm_ctl14">
      <div>
        <label for="ctl00_MainSection_CordaanForm_ctl14_0" value="male" class="long">
            <input type="radio" id="ctl00_MainSection_CordaanForm_ctl14_0" name="ctl00$MainSection$CordaanForm$ctl14"></input>
            male
        </label>
      </div>
      <div>
        <label for="ctl00_MainSection_CordaanForm_ctl14_1" value="female" class="long">
            <input type="radio" id="ctl00_MainSection_CordaanForm_ctl14_1" name="ctl00$MainSection$CordaanForm$ctl14"></input>
            female
        </label>
      </div>
  </div>
4

1 回答 1

1

ASP.NET 通过 ID 识别控件。您在重写 Render 方法时更改了该 ID,因此框架无法再识别它。

于 2009-12-15T11:07:50.480 回答