Cannot access dynamic Textbox/DropDown controls in a dynamic table inside a Panel

Question

Okay so I have this panel inside a table's td.

In this panel I'm creating a dynamic table with text box and drop down controls on a button click.

Problem is that When trying to receive the controls, I FAIL. I've checked literally like more than 25 websites and couldn't find a decent solution or something similar to mine.

Here's the code in which I'm trying to access the controls. It's inside a button event handler.

         for (int i = 0; i < ClickCount; i++)
        {
            //Control myControls = Page.FindControl("table1");
            //Panel myPanel = (Panel)mainTable.FindControl("Panel1");
            //Table myTable = (Table)myPanel.FindControl("table1");
            string FirstName = null;
            string LastName = null;
            string Age = null;
            string PCountry = null;
            string PCommittee = null;

            TextBox txtF = (TextBox)Panel1.FindControl("TextBoxF" + i.ToString());
            FirstName = txtF.Text;

            TextBox txtL = (TextBox)Panel1.FindControl("TextBoxL" + i.ToString());
            LastName = txtL.Text;

            TextBox txtA = (TextBox)Panel1.FindControl("TextBoxA" + i.ToString());
            Age = txtA.Text;

            DropDownList ddlPCountry = (DropDownList)myTable.FindControl("ddlPCountry" + i.ToString());
            PCountry = ddlPCountry.SelectedValue;

            DropDownList ddlPCommittee = (DropDownList)myTable.FindControl("ddlCommittee" + i.ToString());
            PCommittee = ddlPCommittee.SelectedValue;


            string groupInsert = "insert into GroupUser (GroupUserID, FirstName, LastName, Age, PreferredCountry, PreferredCommittee) ";
            groupInsert += "values (@GroupUserID, @FirstName, @LastName, @Age, @PreferredCountry, @PreferredCommittee);";

            SqlCommand group = conn.CreateCommand();
            group.CommandType = CommandType.Text;
            group.CommandText = groupInsert;

            group.Parameters.Add(new SqlParameter("@GroupUserID", ID));
            group.Parameters.Add(new SqlParameter("@FirstName", FirstName));
            group.Parameters.Add(new SqlParameter("@LastName", LastName));
            group.Parameters.Add(new SqlParameter("@Age", Age));
            //group.Parameters.Add(new SqlParameter("@PreferredCountry", ddlPCountry.SelectedValue));
            //group.Parameters.Add(new SqlParameter("@PreferredCommittee", ddlPCommittee.SelectedValue));

            int temp = group.ExecuteNonQuery();

        }

        Response.Redirect("StartPage.aspx");

Here's the creation of the controls in another button event handler.

        Table table = new Table();
        table.ID = "table1";

        for (int i = 0; i < ClickCount; i++)
        {
            TableRow row1 = new TableRow();
            TableRow row2 = new TableRow();
            TableRow row3 = new TableRow();
            TableRow row4 = new TableRow();
            TableRow row5 = new TableRow();
            TableRow row6 = new TableRow();
            TableRow row7 = new TableRow();

            TextBox TxtBoxF = new TextBox();
            TextBox TxtBoxL = new TextBox();
            TextBox TxtBoxA = new TextBox();

            DropDownList ddlPCountry = new DropDownList();
            DropDownList ddlPCommittee = new DropDownList();

            Label lblF = new Label();
            Label lblL = new Label();
            Label lblA = new Label();
            Label lblPCountry = new Label();
            Label lblPCommittee = new Label();

            TxtBoxF.ID = "TextBoxF" + i.ToString();
            TxtBoxL.ID = "TextBoxL" + i.ToString();
            TxtBoxA.ID = "TextBoxA" + i.ToString();

            ddlPCountry.ID = "ddlPCountry" + i.ToString();
            ddlPCommittee.ID = "ddlPCommittee" + i.ToString();

            lblF.ID = "LabelF" + i.ToString();
            lblL.ID = "LabelU" + i.ToString();
            lblA.ID = "LabelA" + i.ToString();
            lblPCountry.ID = "LabelPCountry" + i.ToString();
            lblPCommittee.ID = "LabelPCommittee" + i.ToString();

            lblF.Text = "First Name: ";
            lblL.Text = "Last Name :";
            lblA.Text = "Age: ";
            lblPCountry.Text = "Preferred Country: ";
            lblPCommittee.Text = "Preferred Committee: ";

            ddlPCountry.DataSource = countryDt;
            ddlPCountry.DataValueField = "CountryID";
            ddlPCountry.DataTextField = "CountryName";
            ddlPCountry.DataBind();

            ddlPCommittee.DataSource = committeeDt;
            ddlPCommittee.DataValueField = "CommitteeID";
            ddlPCommittee.DataTextField = "CommitteeName";
            ddlPCommittee.DataBind();

            TxtBoxF.Attributes.Add("runat", "server");
            TxtBoxL.Attributes.Add("runat", "server");
            TxtBoxA.Attributes.Add("runat", "server");

            ddlPCountry.Attributes.Add("runat", "server");
            ddlPCommittee.Attributes.Add("runat", "server");

            for (int a = 0; a < 2; a++)
            {
                TableCell cell1 = new TableCell();
                TableCell cell2 = new TableCell();

                cell1.Controls.Add(lblF);
                cell2.Controls.Add(TxtBoxF);
                row1.Controls.Add(cell1);
                row1.Controls.Add(cell2);
            }

            for (int b = 0; b < 2; b++)
            {
                TableCell cell1 = new TableCell();
                TableCell cell2 = new TableCell();

                cell1.Controls.Add(lblL);
                cell2.Controls.Add(TxtBoxL);
                row2.Controls.Add(cell1);
                row2.Controls.Add(cell2);
            }

            for (int c = 0; c < 2; c++)
            {
                TableCell cell1 = new TableCell();
                TableCell cell2 = new TableCell();

                cell1.Controls.Add(lblA);
                cell2.Controls.Add(TxtBoxA);
                row3.Controls.Add(cell1);
                row3.Controls.Add(cell2);
            }

            for (int d = 0; d < 2; d++)
            {
                TableCell cell1 = new TableCell();
                TableCell cell2 = new TableCell();

                cell1.Controls.Add(lblPCountry);
                cell2.Controls.Add(ddlPCountry);
                row4.Controls.Add(cell1);
                row4.Controls.Add(cell2);
            }

            for (int f = 0; f < 2; f++)
            {
                TableCell cell1 = new TableCell();
                TableCell cell2 = new TableCell();

                cell1.Controls.Add(lblPCommittee);
                cell2.Controls.Add(ddlPCommittee);
                row5.Controls.Add(cell1);
                row5.Controls.Add(cell2);
            }

            table.Rows.Add(row1);
            table.Rows.Add(row2);
            table.Rows.Add(row3);
            table.Rows.Add(row4);
            table.Rows.Add(row5);

        }
        Panel1.Controls.Add(table);
        Panel1.Controls.Add(new LiteralControl("<br />"));
        Panel1.Controls.Add(new LiteralControl("<br />"));
        conn.Close();

Here's the aspx:

<body>
<form id="form1" runat="server">
<div>
<h1>Group Registration</h1>
    <br />
    <table style="width:100%;" id="mainTable" runat="server">
        <tr>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>First Name:</td>
            <td>
                <asp:TextBox ID="txtFirstName" runat="server"></asp:TextBox>
            </td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>Last Name:</td>
            <td>
                <asp:TextBox ID="txtLastName" runat="server"></asp:TextBox>
            </td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>Age:</td>
            <td>
                <asp:TextBox ID="txtAge" runat="server"></asp:TextBox>
            </td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td class="auto-style1">Contact Number:</td>
            <td class="auto-style1">
                <asp:TextBox ID="txtContactNumber" runat="server"></asp:TextBox>
            </td>
            <td class="auto-style1"></td>
        </tr>
        <tr>
            <td>Email Address:</td>
            <td>
                <asp:TextBox ID="txtEmail" runat="server"></asp:TextBox>
            </td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>Institute</td>
            <td>
                <asp:TextBox ID="txtInstitute" runat="server" Width="400px"></asp:TextBox>
            </td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td class="auto-style1">Preferred Country:</td>
            <td class="auto-style1">
                <asp:DropDownList ID="ddlCountry" runat="server">
                </asp:DropDownList>
            </td>
            <td class="auto-style1"></td>
        </tr>
        <tr>
            <td>Preferred Committee:</td>
            <td>
                <asp:DropDownList ID="ddlCommittee" runat="server">
                </asp:DropDownList>
            </td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>Username:</td>
            <td><asp:TextBox ID="txtUsername" runat="server"></asp:TextBox>
            </td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>Password:</td>
            <td>
                <asp:TextBox ID="txtPassword" runat="server" TextMode="Password"></asp:TextBox>
            </td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>&nbsp;</td>
            <td>
                <asp:Panel ID="Panel1" runat="server">
                </asp:Panel>
            </td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>&nbsp;</td>
            <td>
                <asp:Button ID="btnAddAnother" runat="server" OnClick="btnAddAnother_Click" Text="Add Another Member" />
            </td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td>&nbsp;</td>
            <td>
                <asp:Button ID="btnRegister" runat="server" Text="Sign Up" OnClick="btnRegister_Click" />
            </td>
            <td>&nbsp;</td>
        </tr>
    </table>
</div>
</form>

In the html of the page the hierarchy goes as follows Table> Panel> Dynamic Table> Dynamic Controls — Edd Chang, Jun 06 '14 at 15:05
Can you view source and provide the HTML/ASP.NET code after page load so we can see how/what your objects look like? — lucidgold, Jun 06 '14 at 15:19

lucidgold · Accepted Answer · 2014-06-06T16:45:38.990

1

Problem 1:

You cannot access any control on the server-side (from C# code-behind) if it dosent have the attribute runat="server". So, you must add:

.Attributes.Add("runat", "server");

to every control that you want to access in your button event handler. After each control declaration, you must do the following:

TxtBoxF.Attributes.Add("runat", "server");
TxtBoxL.Attributes.Add("runat", "server");
TxtBoxA.Attributes.Add("runat", "server");

ddlPCountry.Attributes.Add("runat", "server");
ddlPCommittee.Attributes.Add("runat", "server");

lblF.Attributes.Add("runat", "server");
lblL.Attributes.Add("runat", "server");
lblA.Attributes.Add("runat", "server");
lblPCountry.Attributes.Add("runat", "server");
lblPCommittee.Attributes.Add("runat", "server");

Problem 2:

You should be searching for your controls in Panel1, not the tables. However, since I cannot see your ASPX Code, I am unsure if your panel has the attribute runat=server.

I suggest you make the following change to your ASPX page:

Change the after tag:

<form id="form1" runat="server">
<div>

to

<div id="myControls" runat="server">

Then, at the end of your dynamic control creation, change:

Panel1.Controls.Add(table);
Panel1.Controls.Add(new LiteralControl("<br />"));
Panel1.Controls.Add(new LiteralControl("<br />"));

to

myControls.Controls.Add(table);
myControls.Controls.Add(new LiteralControl("<br />"));
myControls.Controls.Add(new LiteralControl("<br />"));

Then, in your control access code you need to change:

TextBox txtF = (TextBox)Panel1.FindControl("TextBoxF" + i.ToString());
TextBox txtL = (TextBox)Panel1.FindControl("TextBoxL" + i.ToString());
TextBox txtA = (TextBox)Panel1.FindControl("TextBoxA" + i.ToString());
DropDownList ddlPCountry = (DropDownList)myTable.FindControl("ddlPCountry" + i.ToString());
DropDownList ddlPCommittee = (DropDownList)myTable.FindControl("ddlCommittee" + i.ToString());

to

TextBox txtF = (TextBox)myControls.FindControl("TextBoxF" + i.ToString());
TextBox txtL = (TextBox)myControls.FindControl("TextBoxL" + i.ToString());
TextBox txtA = (TextBox)myControls.FindControl("TextBoxA" + i.ToString());
DropDownList ddlPCountry = (DropDownList)myControls.FindControl("ddlPCountry" + i.ToString());
DropDownList ddlPCommittee = (DropDownList)myControls.FindControl("ddlCommittee" + i.ToString());

Possible Problem 3:

New controls should be created during Page Init. So you should take all your dynamic control creation code and put it inside page_init:

protected void Page_Init(object sender, EventArgs e)
{
   // Put dynamic controls creation here!
}

edited Jun 06 '14 at 16:45

answered Jun 06 '14 at 15:20

lucidgold

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How do I create the controls on page load? And the first solution did not work.... Please enlighten me more about the second solution. Thanks.. – Edd Chang Jun 06 '14 at 15:48
Can you update your code, I would like to see what it looks like now? I have updated my code to clerify... – lucidgold Jun 06 '14 at 15:51
I dont see your ASPX code, and you need to also add lblF.Attributes.Add("runat", "server"); lblL.Attributes.Add("runat", "server"); lblA.Attributes.Add("runat", "server"); lblPCountry.Attributes.Add("runat", "server"); lblPCommittee.Attributes.Add("runat", "server"); – lucidgold Jun 06 '14 at 16:26
Yeah I know. But as I'm not going to need them further on I decided not to add them in the code. I only need access to the three textboxes and two dropdownlists. – Edd Chang Jun 06 '14 at 16:38
The aspx has been added.. Take a look. – Edd Chang Jun 06 '14 at 16:40
So basically in a table's TD I have a panel (Panel1) and in that panel I'm adding a dynamic table and controls... – Edd Chang Jun 06 '14 at 16:41
If I put the dynamic control creation in Page_Init so do I remove it from the button's event handler? – Edd Chang Jun 06 '14 at 16:50
yes, just copy and paste the code and put it inside Page_Init... Did you make the other changes? – lucidgold Jun 06 '14 at 16:52
Page_Init worked. Wow. I need to adjust some stuff though. Can I know what does Page_Init do? And how do I create new controls on a button click if all my code is in Page_Init? – Edd Chang Jun 06 '14 at 16:56
Can you accept my answer if it has helped you? This will also reduce chatter on this question and let everyone else know that the OP is happy and confirms the answers to share the knowlege. – lucidgold Jun 06 '14 at 17:29
I made the tick green. :) – Edd Chang Jun 06 '14 at 17:39
Can I know what does Page_Init do? And how do I create new controls on a button click if all my code is in Page_Init? – Edd Chang Jun 07 '14 at 05:11

Cannot access dynamic Textbox/DropDown controls in a dynamic table inside a Panel

1 Answers1