如何在代码后面的占位符中获取文本框值？

Question

我创建了一些文本框，我想动态获取它们的值。 简而言之，我解释一下我的页面：

我的下拉列表有数字 1 到 15。当用户选择数字时，我将文本框创建为所选数字。 例如;用户选择 3，我创建 3 个文本框，用户在文本框中写一些东西。 这是我的代码： aspx 侧：

  <asp:DropDownList ID="ddlUserSelected" AutoPostBack="true" OnSelectedIndexChanged="ddlUserSelected_SelectedIndexChanged" runat="server">
 <asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>
 <asp:Button ID="btnSave" runat="server" Text="Save" OnClick="btnSave_Click"/>

代码背后：

    protected void ddlUserSelected_SelectedIndexChanged(object sender, EventArgs e)
    {
     for (int a = 1; a <= int.Parse(ddlUserSelected.SelectedItem.Text); a++)
            {

                TextBox txtDate = new TextBox();
                Label lbl = new Label();          
                lbl.Text = "<br/>";        
                txtDate .Width = 70;
                txtDate .CssClass = "tbl";
                txtDate .ID = "txtDate" + a;                  
                PlaceHolder1.Controls.Add(txtDate);            
                PlaceHolder1.Controls.Add(lbl);

            }
}

我还有保存按钮。

protected void btnSave_Click(object sender, EventArgs e)
{

   for (int a = 1; a <= int.Parse(ddlUserSelected.SelectedItem.Text); a++)
    {              
      //I want to get each textbox value               
    }

}

注意：for循环没关系（可以去掉）我的主要目的是获取文本框的值。

如何在btnSave_Click 方法中获取文本框值？

Answer 1

问题

如果您将控件动态添加到页面，则需要在 Page Init 或 Page Load 上重新加载它们。

否则，您在回帖时将无法找到它们。

ASPX

<asp:DropDownList ID="ddlUserSelected" AutoPostBack="true" 
    OnSelectedIndexChanged="ddlUserSelected_SelectedIndexChanged" 
    runat="server">
    <asp:ListItem Text="Select one" />
    <asp:ListItem Text="1" />
    <asp:ListItem Text="2" />
    <asp:ListItem Text="3" />
    <asp:ListItem Text="4" />
    <asp:ListItem Text="5" />
</asp:DropDownList>
<br/>
<asp:PlaceHolder ID="PlaceHolder1" runat="server"/>
<asp:Button ID="btnSave" runat="server" Text="Save" OnClick="btnSave_Click" />

代码隐藏

private int Total
{
    get
    {
        int total;
        if (Int32.TryParse(ddlUserSelected.SelectedItem.Text, out total)) 
            return total;
        return 0;
    }
}

protected void Page_Load(object sender, EventArgs e)
{
    CreateTextBoxes(Total);
}

protected void ddlUserSelected_SelectedIndexChanged(object sender, EventArgs e)
{
    CreateTextBoxes(Total);
}

protected void btnSave_Click(object sender, EventArgs e)
{
    int total = Total;
    for (int a = 1; a <= total; a++)
    {
        var textbox = PlaceHolder1.FindControl("txtDate" + a) as TextBox;
    }
}

private void CreateTextBoxes(int total)
{
    for (int a = 1; a <= total; a++)
    {
        // Make sure we do not add same ID again
        if (PlaceHolder1.FindControl("txtDate" + a) == null)
        {
            TextBox txtDate = new TextBox();
            Label lbl = new Label();
            lbl.Text = "<br/>";
            txtDate.Width = 70;
            txtDate.CssClass = "tbl";
            txtDate.ID = "txtDate" + a;
            PlaceHolder1.Controls.Add(txtDate);
            PlaceHolder1.Controls.Add(lbl);
        }
    }
}

Answer 2

下面的代码会帮助你

 protected void ddlUserSelected_SelectedIndexChanged(object sender, EventArgs e)
  {
    for (int a = 1; a <= int.Parse(ddlUserSelected.SelectedItem.Text); a++)
    {

        TextBox txtDate = new TextBox();
        Label lbl = new Label();
        lbl.Text = "<br/>";
        txtDate.Width = 70;
        txtDate.CssClass = "tbl";
        txtDate.ID = "txtDate" + a;
        PlaceHolder1.Controls.Add(txtDate);
        PlaceHolder1.Controls.Add(lbl);

    }
  }
  protected void btnSave_Click(object sender, EventArgs e)
  {

    for (int a = 1; a <= int.Parse(ddlUserSelected.SelectedItem.Text); a++)
    {
        if(Request.Form.Get("txtDate" + a.ToString()) != null)
        {
            var str = Request.Form.Get("txtDate" + a.ToString());
        }        
    }
  }

如果您使用母版页，请使用以下代码

        if (Request.Form.Get("ctl00$ContentPlaceHolder1$txtDate" + a.ToString()) != null)
        {
            var str = Request.Form.Get("ctl00$ContentPlaceHolder1$txtDate" + a.ToString());
        }

Answer 3

protected void btnSave_Click(object sender, EventArgs e)
            {

               for (int a = 1; a <= int.Parse(ddlUserSelected.SelectedItem.Text); a++)
                {              
                     string value = Request.Form["txtDate" + a];
                }

            }