How to add rows to a data table

Question

I have created a datatable globaly and i have add columns to it in the page load event. Now i want to add data to it in a button click event.. When I do it as below I get a error saying....

Column 'catID' does not belong to table

What is the solution... Do i need to use sessions... ? the code is like below

    public partial class Default2 : System.Web.UI.Page
{
    DataTable dtSelectedSeats = new DataTable();

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            dtSelectedSeats.Columns.Add("catID", typeof(string));
            dtSelectedSeats.Columns.Add("seatID", typeof(string));
        }

    }
    protected void seat_Click(object sender, EventArgs e)
    {
        Button button = (Button)sender;

        if (button.BackColor == Color.Cyan)
        {
            button.BackColor = Color.Lime;

            addSeat(button.Text);
        }

    }

    private void addSeat(string seatNo)
    {
        DataRow dr;
        dr = dtSelectedSeats.NewRow();
        dr["catID"] = ddlCategory.SelectedItem.Value.ToString();
        dr["seatID"] = seatNo;
        dtSelectedSeats.Rows.Add(dr);
    }
}

Samiey Mehdi · Accepted Answer · 2013-09-08 06:18:17Z

1

ASPX:

<asp:DropDownList ID="ddlCategory" runat="server">
<asp:ListItem>a</asp:ListItem>
<asp:ListItem>b</asp:ListItem>
<asp:ListItem>c</asp:ListItem>
</asp:DropDownList>
<asp:Button ID="seat" runat="server" BackColor="Cyan" onclick="seat_Click" Text="1" />
<asp:Button ID="Button1" runat="server" BackColor="Cyan" onclick="Button1_Click" Text="2" />
<asp:Button ID="Button2" runat="server" BackColor="Cyan" onclick="Button2_Click" Text="3" /><br />
<asp:GridView ID="GridView1" runat="server"/>

Code behind:

protected void seat_Click(object sender, EventArgs e)
{
    Button button = (Button)sender;
    if (button.BackColor == Color.Cyan)
    {
        button.BackColor = Color.Lime;
        addSeat(button.Text);
    }
}
private void addSeat(string seatNo)
{
    if (Session["dt"] == null)
    {
        Response.Write("DataTable not exist!");
        return;
    }
    DataTable dtSelectedSeats = (DataTable)Session["dt"];
    DataRow dr = dtSelectedSeats.NewRow();
    dr["catID"] = ddlCategory.SelectedItem.Value.ToString();
    dr["seatID"] = seatNo;
    dtSelectedSeats.Rows.Add(dr);
    GridView1.DataSource = dtSelectedSeats;
    GridView1.DataBind();
    Session["dt"] = dtSelectedSeats;
}
protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        DataTable dtSelectedSeats = new DataTable();
        dtSelectedSeats.Columns.Add("catID", typeof(string));
        dtSelectedSeats.Columns.Add("seatID", typeof(string));
        Session["dt"] = dtSelectedSeats;
    }
}
protected void Button1_Click(object sender, EventArgs e)
{
    seat_Click(sender, e);
}
protected void Button2_Click(object sender, EventArgs e)
{
    seat_Click(sender, e);
}

edited Sep 8, 2013 at 6:18

answered Sep 8, 2013 at 6:08

Samiey Mehdi

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2 Comments

Lakindu Nanayakkara Over a year ago

Does it means i have to use Sessions ?

Samiey Mehdi Over a year ago

You can use Session["dt"] or ViewState["dt"]. if you uses only one page ViewState is best way but if you use multiple pages Session is best way.

ojlovecd · Accepted Answer · 2013-09-08 03:52:54Z

0

just remove the if (!IsPostBack) coz when you click the button , the page will post back.

answered Sep 8, 2013 at 3:52

ojlovecd

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1 Comment

Lakindu Nanayakkara Over a year ago

It works.. but...When i click the first button.. it added to the datatable.. when i click another button the datatable refreshes and the previous data have lost.. I want to keep the previous records and add the new record to the data table

ManojKanojiya · Accepted Answer · 2013-09-08 03:59:09Z

0

Your Code is perfectly correct for DataTable, the error you are getting may be for some different problem. Please specify correctly your error

answered Sep 8, 2013 at 3:59

ManojKanojiya

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1 Comment

Radim Köhler Over a year ago

Please, try to read this stackoverflow.com/about, to get more understanding about questions/answers here on SO. Your contribution is not answering the question. It is more a comment, which you can add once you'll increase your reputation: stackoverflow.com/faq#reputation

maccettura · Accepted Answer · 2013-09-08 04:59:01Z

0

Just off the top of my head it looks as if you are adding the rows in the wrong event. I'm not sure your DataTable has been initialized at the point you are adding columns to it (thus throwing away your changes). Try putting your PageLoad code into PagePrerender and see if that gives you a better result.

answered Sep 8, 2013 at 4:59

maccettura

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