Update panel is not working when we use dropdownlist

Question

1.00/5 (1 vote)

See more:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Student_FeedbackForm.aspx.cs" MasterPageFile ="~/Master_Student_Form.master" Inherits="Student_FeedbackForm" %>

<asp:Content ContentPlaceHolderID="ContentPlaceHolder1";ID="cnt1" runat="server">

XML

<table align="center" style="width: 31%">
       <tr>
           <td>
             <asp:Label ID="lblMsg" Text ="" runat ="server" Font-Bold="True" ForeColor="Red"></asp:Label>
           </td>
       </tr>
    <tr>
       <td>
           <asp:Label ID="StudentFeedbackForm" Text = "Student Feedback Form" runat ="server" Font-Bold="True" ForeColor="Blue"></asp:Label>
       </td>
    </tr>
    </table>

       <table align="center" style="width:80%">
      <tr>

           <td class="style1">
              <asp:Label ID= "lblCourse" runat= "Server" Font-Bold="True" ForeColor="Blue" Width="75px" Font-Names="Verdana">Course</asp:Label>
              <asp:DropDownList ID="ddlcourse" runat="server" AutoPostBack="true" Width="190px"
                   OnSelectedIndexChanged="ddlcourse_SelectedIndexChanged" Font-Names="Verdana"></asp:DropDownList>
           </td>
           <td >
             <asp:Label ID= "lblBatch" runat= "Server" Font-Bold="True" ForeColor="Blue"
                   Font-Names="Verdana">Batch</asp:Label>
             <asp:DropDownList ID="ddlbatch" runat = "server"
             AutoPostBack ="true" Width ="243px" Font-Names="Verdana" Height="20px"
                   onselectedindexchanged="ddlbatch_SelectedIndexChanged"></asp:DropDownList>
           </td>
      </tr>

XML

<asp:Panel id="pnlfac" runat="server" backcolor="Beige" ScrollBars="Auto" bordercolor ="Black"
      borderstyle="Solid" borderwidth="1px" height="226px" Width="1095px"
      HorizontalAlign="Center">
          <asp:GridView id="gvfaculty" runat="server" backcolor="LightGoldenrodYellow"
            BorderColor="Tan" width="1090px" ForeColor="Black" AutoGenerateColumns ="False"
                EnableModelValidation="True"
              OnRowCreated ="gvfaculty_RowCreated">
                 <FooterStyle BackColor="Tan"/><AlternatingRowStyle BackColor="PaleGoldenrod" />
                 <Columns>
                 <asp:BoundField DataField="Facname" HeaderText="Faculty" >
                     <ItemStyle Font-Names="Verdana" Font-Size="Small" HorizontalAlign="Left" />
                 </asp:BoundField>
                 <asp:BoundField DataField="Facid" HeaderText="Facultyid" />
                 <asp:TemplateField HeaderText="Does the Faculty come well prepared for his subject">
                 <ItemTemplate>
                 <asp:DropDownList ID="DropDownList1" runat="server" AppendDataBoundItems="true">
                 </asp:DropDownList>
                 </ItemTemplate>
                     <ItemStyle Font-Names="Verdana" Font-Size="Small" HorizontalAlign="Left" />
                 </asp:TemplateField>

                 <asp:TemplateField HeaderText="Is he loud and clear in his speech">


                  <ItemTemplate>
                  <asp:DropDownList ID="DropDownList2" runat="server" AppendDataBoundItems="true"></asp:DropDownList>
                  </ItemTemplate>
                  </asp:TemplateField>

<HeaderStyle BackColor="Tan" Font-Bold="True" HorizontalAlign="Left" Font-Names="Verdana" Font-Size="Small" /><pagerstyle backcolor="PaleGoldenrod" forecolor="DarkSlateBlue" horizontalalign="Center"><SelectedRowStyle BackColor="DarkSlateBlue" ForeColor="GhostWhite" />

ddlbatch selected index change code as follows

protected void ddlbatch_SelectedIndexChanged(object sender, EventArgs e)
{
lblMsg.Text = "";
try
{

C#

lblMsg.Text = "";
        try
        {
             sql = "SELECT sel.fac_id as Facid, fac.facname as facname,fac.type FROM Tb_Presea_Feedback_Launch l,Tb_Presea_Faculty_Selected sel,";
            sql = sql + "Tb_Presea_Faculty_Master fac where l.launch_id = sel.launch_id and l.batch_id = '" + ddlbatch.SelectedValue.ToString().Trim() + "'";
            sql = sql + "and l.active = 'A' and fac.facid = sel.fac_id and fac.type = 'F'";
            DataTable dt = new DataTable();
            dt.Columns.Add(new DataColumn("facname", typeof(string)));
            dt.Columns.Add(new DataColumn("Facid", typeof(string)));
            dr = scon.ReadSql(sql);
            gvfaculty.DataSource = dr;
            gvfaculty.DataBind();

             if (gvfaculty.Rows.Count <= 0)
            {
                lblMsg.Text = "Feedback is not launched for this batch";
                ScriptManager.RegisterStartupScript(this, GetType(), "", "alert('Feedback is not launched for this batch')", true);
                return;
            }
        }
        catch (Exception e1)
        {
            lblMsg.Text = e1.Message.ToString();
            return;
        }

setintialrow();
}
catch (Exception ex)
{
lblMsg.Text = "Unable to Load Data" + ex.Message.ToString();
return;
}
}

In the run mode screen as follows

Studentfeedback form
Course ddlcourse Batch ddlbatch

When i select the ddl course in batch all batch details will be displayed and when i select the ddlbatch the gridview will be displayed.

But when i use the update panel in source as follows

XML

<asp:UpdatePanel ID = "UpdatePanel1" ChildrenAsTriggers="true" runat ="server">
             <ContentTemplate>

<asp:UpdatePanel ID = "UpdatePanel1" ChildrenAsTriggers="true" runat ="server">
<contenttemplate>

<asp:Label ID="lblMsg" Text ="" runat ="server" Font-Bold="True" ForeColor="Red">

<asp:Label ID="StudentFeedbackForm" Text = "Student Feedback Form" runat ="server" Font-Bold="True" ForeColor="Blue">

<asp:Label ID= "lblCourse" runat= "Server" Font-Bold="True" ForeColor="Blue" Width="75px" Font-Names="Verdana">Course
<asp:DropDownList ID="ddlcourse" runat="server" AutoPostBack="true" Width="190px"
OnSelectedIndexChanged="ddlcourse_SelectedIndexChanged" Font-Names="Verdana">

<asp:Label ID= "lblBatch" runat= "Server" Font-Bold="True" ForeColor="Blue"
Font-Names="Verdana">Batch
<asp:DropDownList ID="ddlbatch" runat = "server"
AutoPostBack ="true" Width ="243px" Font-Names="Verdana" Height="20px"
onselectedindexchanged="ddlbatch_SelectedIndexChanged">
<asp:RequiredFieldValidator ID="RequiredFieldValidator21" runat="server"
ErrorMessage="Please Select Batch" ControlToValidate="ddlbatch"
Font-Names="Verdana" Font-Size="Medium"
InitialValue="--Please Select the Batch Date--">

<asp:UpdateProgress ID="UpdateProgress2" runat="server">
<progresstemplate>
<asp:Label ID="Label20" runat="server" Font-Size="Large"
Text="Please Wait ...">
<img alt="" src ="images/Prog_2.gif"
style="width: 405px; height: 78px" />

In the run mode screen as follows

Studentfeedback form
Course ddlcourse Batch ddlbatch

When i select the ddl course in batch all batch details will be displayed and when i select the ddlbatch the gridview will not be displayed.

for that how can i do in asp.net using c#.

Posted 29-Dec-14 21:47pm

narasiman1

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Shahnawazcode · Answer 1 · 2014-12-29T23:03:00

XML

t sounds like you may not be using the UpdatePanel feature properly. If you have the UpdatePanel set to update when children fire events, only the UpdatePanel should refresh, not the entire page. The code below seems to behave similar to what you are seeking. When changing the drop down, only the update panel posts back to the server and when you refresh the page, you can get the value out of the session.

ASPX CODE

<form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <div>
        Current Time: <asp:Label ID="lblTime" runat="server" /><br />
        Session Value: <asp:Label ID="lblSessionValue" runat="server" /><br />
        <br />
        <asp:UpdatePanel ID="upSetSession" runat="server">
            <ContentTemplate>
                <asp:DropDownList ID="ddlMyList" runat="server"
                    onselectedindexchanged="ddlMyList_SelectedIndexChanged"
                    AutoPostBack="true">
                    <asp:ListItem>Select One</asp:ListItem>
                    <asp:ListItem>Maybe</asp:ListItem>
                    <asp:ListItem>Yes</asp:ListItem>
                </asp:DropDownList>
            </ContentTemplate>
            <Triggers>
                <asp:AsyncPostBackTrigger ControlID="ddlMyList"
                    EventName="SelectedIndexChanged" />
            </Triggers>
        </asp:UpdatePanel>
    </div>
</form>

CODE BEHIND

C#

protected void Page_Load(object sender, EventArgs e)
    {
        this.lblTime.Text = DateTime.Now.ToShortTimeString();
        if (Session["MyValue"] != null)
            this.lblSessionValue.Text = Session["MyValue"].ToString();
    }

    protected void ddlMyList_SelectedIndexChanged(object sender, EventArgs e)
    {
        Session.Remove("MyValue");
        Session.Add("MyValue", this.ddlMyList.SelectedValue);
    }