Dynamically adding a command button to a GridView

Question

I had a problem trying to add a button to my grid. My GridView is first loaded with data in the PageLoad event.

Then I take the data in the first cell of each row and create a button that will link to the URL. To get the url, I have to execute a query with the data in the first cell as a parameter. At first I did this in the RowDataBound event, but defeating this query for each row made it very slow.

So, I decided to add a button that will retrieve the URL only when you click the button.

Here is my gridview:

<asp:GridView ID="gvResults" runat="server"
    OnRowDataBound="gvResults_RowDataBound"
    OnRowCommand="gvResults_RowCommand">               
</asp:GridView>    

And my code is:

protected void gvResults_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.DataItem != null)
    {
        LinkButton lb = new LinkButton();
        lb.CommandArgument = e.Row.Cells[0].Text;
        lb.CommandName = "NumClick";
        lb.Text = e.Row.Cells[0].Text;

        e.Row.Cells[0].Controls.Add((Control)lb);
    }
}


protected void gvResults_RowCommand(object sender, CommandEventArgs e)
{
    switch (e.CommandName.ToLower())
    {
        case "numclick":
            string url = GetUrl(e.CommandArgument.ToString());
            Response.Redirect(url);
            break;
        default:
            break;
    }
}

The grid generates a fine; a button is added to the grid for each row. But when I click on it, the RowCommand event does not fire, and the page just refreshes.

Does anyone know what the problem is?

Answer 1

? gridview ( , ), RowDataBound.

:

<Columns>
    <asp:TemplateField HeaderText="SomeHeaderText">
            <ItemTemplate>
                <asp:LinkButton ID="lnkBtn" runat="server" CommandName="NumClick" CommandArgument= '<%# (string)Eval("dbValue") %>'  Text='<%# (string)Eval("dbValue") %>'></asp:LinkButton>
            </ItemTemplate>
        </asp:TemplateField>        
    <asp:BoundField></asp:BoundField>
    <asp:BoundField></asp:BoundField>
    <asp:BoundField></asp:BoundField>
</Columns>

---

RowCommand , .

.

, , .

Answer 2

. , , , .

, RowDataBound, , . , , , . ( ), , .

, . GridView, LinkButton(), e.Row.Cells[0].FindControl("buttonId") . , Command ( RowCommand) , ( CommandArgument )

[Edit] : . new Control() ( ), Page.LoadControl(typeof(Control)). , , !

Answer 3

Since the control is dynamically added to the data binding, and you need to bind the data to the gridview for each postback, each control will click. The event does not fire, because at the time when it should be fired, it does not exist, as in the last iteration of the page.

I notice that you do not have logic to determine if a button should be there, and it always goes to cell [0].

You must put this button in the TemplateItem so that it exists properly. If you need to do this in code, you are probably best off doing this in the RowCreated event.