Question

我正在创建一个调查页面，其中包含一系列问题和答案，可以是radiobuttonlists，checkboxlists或textboxes。使用Controls.Add。

将这些控件动态添加到其ItemDataBound事件中的Repeater中

我设法渲染页面正常但是当我提交表单并迭代转发器中的控件以获取radiobuttons和textbox值的选定值时，FindControl返回null。获取所选值需要做什么？我已经尝试迭代RepeaterItems，但也返回null。我尝试过不同类型的FindControl，但它从未解析控件类型。如果我在Repeater中添加声明性DataBinder，就像这样

<asp:Repeater ID="rptSurvey" runat="server" Visible="true" EnableViewState="true" >
 <ItemTemplate>
      <%# DataBinder.Eval(Container.DataItem, "Question") %>
 </ItemTemplate>
</asp:Repeater>

但是，我想要动态添加控件，但在执行此操作时，我无法在提交时获取所选值。这是我的代码的主要结构...

<html>
<asp:Repeater ID="rptSurvey" runat="server" Visible="true">                      
</asp:Repeater>
<asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="btnSubmit_Click" />
</html>

protected void Page_Load(object sender, EventArgs e)
{

  ...

            if (!IsPostBack)
            {
                rptSurvey.DataSource = GetQuestions();
                rptSurvey.DataBind();
            }
  ...

}

protected void rptSurvey_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
            {
                string question = (DataBinder.Eval(e.Item.DataItem, "Question")).ToString();

              litQuestion = new Literal();
                litQuestion.Text = question;
        RadioButtonList rblAnswer = (RadioButtonList)item;


                    rptSurvey.Controls.Add(rblAnswer);
    }
}

protected void btnSubmit_Click(object sender, EventArgs e)
{
           ...
            Dictionary<int, string> answers = new Dictionary<int, string>();

            try
            {
                var list = FindControls(rptSurvey, c => c is RadioButtonList || c is CheckBoxList || c is TextBox);

                foreach (Control item in list)
                {
                    QuestionId = int.Parse(Questions.Rows[list.IndexOf(item)][0].ToString());

                    if (item is TextBox)
                    {
                        TextBox txtAnswer = (TextBox)item;
                        answers.Add(QuestionId, txtAnswer.Text);
                    }
                    else if (item is RadioButtonList)
                    {
                        RadioButtonList rblAnswer = (RadioButtonList)item;
                        answers.Add(QuestionId, rblAnswer.SelectedItem.Text);
                    }

                    else if (item is CheckBoxList)
                    {
                        // Iterate through the Items collection of the CheckBoxList 
                        string cblMultiAnswer = "";
                        for (int i = 0; i < cblAnswer.Items.Count; i++)
                        {
                            if (cblAnswer.Items[i].Selected)
                            {
                                cblMultiAnswer += cblAnswer.Items[i].Value + ",";
                            }
                        }

                        answers.Add(QuestionId, cblMultiAnswer);
                    }
                }

               bSurvey.BLInsertSurveyAnswers(answers, dateCreated, _userEmail);
            }
        }

        public static List<Control> FindControls(Control parent, Predicate<Control> match)
        {
            var list = new List<Control>();
            foreach (Control ctl in parent.Controls)
            {
                if (match(ctl))
                    list.Add(ctl);
                list.AddRange(FindControls(ctl, match));
            }
            return list;
}

Answer 1

您必须首先创建控制树（始终 - 不仅在非回发上）。在oninit或onpreload事件中执行此操作。

看这里：http://www.4guysfromrolla.com/articles/081402-1.aspx

无法在转发器中找到动态添加控件的选定值

1 个答案: