Question

我想从动态生成的文本框中获取价值。下面给出的是我的代码，但每次获得null值。

Default.aspx的：

 <asp:Panel ID="Panel1" runat="server" style="width:460px">
 <asp:PlaceHolder id="Area1" runat="server"></asp:PlaceHolder>
  </asp:Panel>


<asp:Button ID="Button1" runat="server" Text="Button" 
   onclick="Button1_Click1" />
<asp:Button ID="Button2" runat="server" Text="save" onclick="Button2_Click" />

Default.aspx.cs

 protected void Button1_Click1(object sender, EventArgs e)
 {
    CreateTextBox();

 }
 public void CreateTextBox()
 {

    int rowCount = 0;
    //initialize a session.
    rowCount = Convert.ToInt32(Session["clicks"]);

    rowCount++;

    //In each button clic save the numbers into the session.
    Session["clicks"] = rowCount;


    //Create the textboxes and labels each time the button is clicked.
    for (int i = 0; i < rowCount; i++)
    {

        TextBox TxtBoxU = new TextBox();

        TextBox TxtBoxE = new TextBox();

        Label lblU = new Label();
        Label lblE = new Label();

        TxtBoxU.ID = "TextBoxU" + i.ToString();
        TxtBoxE.ID = "TextBoxE" + i.ToString();

        lblU.ID = "LabelU" + i.ToString();
        lblE.ID = "LabelE" + i.ToString();


        lblU.Text = "Header " + (i + 1).ToString() + " : ";
        lblE.Text = "Value " + (i + 1).ToString() + " : ";

        //Add the labels and textboxes to the Panel.
        Area1.Controls.Add(lblU);
        Area1.Controls.Add(TxtBoxU);

        Area1.Controls.Add(lblE);
        Area1.Controls.Add(TxtBoxE);
    }
}
protected void Button2_Click(object sender, EventArgs e)
{
    int count=Convert.ToInt32( Session["clicks"]);
    for(int j=0;j<count;j++)
    {

        TextBox aa = (TextBox)Area1.FindControl("TextBoxU"+j);
        Response.Write(aa.Text);

        TextBox bb = (TextBox)Area1.FindControl("TextBoxE" + j);
        Response.Write(bb.Text);

    }
 }

所以，请给出适当的解决方案。谢谢。

Answer 1

我认为你还必须在CreateTextBox();事件中调用Page_Load函数。

您的Button2_Click原因页面重新加载，下次当您的页面加载文本框并且未创建标签时，当您尝试通过其ID访问它们时，您将获得空值。

您需要检查哪个事件引发了回发以及您需要调用的Button2_Click CreateTextBox();功能。

在 Page_Load

上

  protected void Page_Load(object sender, EventArgs e)
     {
       if (IsPostBack)
        {
          string eventName = getPostBackControlName();//Checks for the event that
            //Caused postBack 
          if (eventName == "Button2")
           CreateTextbox();

         }
      }

getPostbackControlName - Here

private string getPostBackControlName()
        {
            Control control = null;
            //first we will check the "__EVENTTARGET" because if post back made by       the controls
            //which used "_doPostBack" function also available in Request.Form collection.
            string ctrlname = Page.Request.Params["__EVENTTARGET"];
            if (ctrlname != null && ctrlname != String.Empty)
            {
                control = Page.FindControl(ctrlname);
            }
            // if __EVENTTARGET is null, the control is a button type and we need to
            // iterate over the form collection to find it
            else
            {
                string ctrlStr = String.Empty;
                Control c = null;
                foreach (string ctl in Page.Request.Form)
                {
                    //handle ImageButton they having an additional "quasi-property" in their Id which identifies
                    //mouse x and y coordinates
                    if (ctl.EndsWith(".x") || ctl.EndsWith(".y"))
                    {
                        ctrlStr = ctl.Substring(0, ctl.Length - 2);
                        c = Page.FindControl(ctrlStr);
                    }
                    else
                    {
                        c = Page.FindControl(ctl);
                    }
                    if (c is System.Web.UI.WebControls.Button ||
                             c is System.Web.UI.WebControls.ImageButton)
                    {
                        control = c;
                        break;
                    }
                }
            }
            return control.ID;

        }

protected void Button1_Click1(object sender, EventArgs e)
 {
    CreateTextBox();

 }

protected void Button2_Click(object sender, EventArgs e)
{
    int count=Convert.ToInt32( Session["clicks"]);
    for(int j=0;j<count;j++)
    {

        TextBox aa = (TextBox)Area1.FindControl("TextBoxU"+j);
        Response.Write(aa.Text);

        TextBox bb = (TextBox)Area1.FindControl("TextBoxE" + j);
        Response.Write(bb.Text);

    }
 }

如何从asp.net c中动态生成的多个文本框中获取多个值

1 个答案: