Question

I’ve some UserControls which are created dynamically, with parameters :

foreach (DataRow dr in drc)
{
    question = (from ques in bdd.QUESTION where ques.ID_QUESTION == idQuestion select ques).FirstOrDefault();
    List<Object> listParams = new List<Object>();
    listParams.Add(question);
    AdminQuestion qa = (AdminQuestion)(Controller.LoadControl(Page, "~/UserControls/AdminQuestion.ascx", listParams.ToArray()));
    pnl_question_list.Controls.Add(qa);
}

This is a method I found on SoF and it works great.
This method is called when I click on a button, and all my usercontrols are correctly created.
In this usercontrol, I have a button :

<asp:Button ID="btn_validation_modify_question" runat="server" Text="Modifier" 
            CssClass="clear_left_float_left myBouton myBoutonEnvoyer" 
            OnClick="btn_validation_modify_question_Click"/>

And my method :

protected void btn_validation_modify_question_Click(object sender, EventArgs e)
{
    QUESTION q = (from m in bdd.QUESTION where m.ID_QUESTION == question.ID_QUESTION select m).FirstOrDefault();
    q.MESSAGE = txt_modify_question_message.InnerText;
    q.ID_THEME = new Guid(ddl_modify_question_theme.SelectedValue);
    bdd.ApplyCurrentValues<QUESTION>("QUESTION", q);
    bdd.SaveChanges();
}

But when I click on the button, it don’t apply the method, and reload the page, like if I didn’t have any declared method.

Is there something I don’t know? I already used this technique and everything worked…

Answer 1

If you add controls dynamically, you’ll normally need to do it on Init or PreInit page events. Otherwise event handlers will never work.

So, dynamically added controls must be programmatically added to the Web page on each and every page visit. The best time to add these controls is during the initialization stage of the page life cycle, which occurs before the load view state stage. That is, we want to have the control hierarchy complete before the load view state stage arrives. For this reason, it is best to create an event handler for the Page class’s Init event in your code-behind class, and add your dynamic controls there.

Note You may be able to get away with loading your controls in the
Page_Load
event handler and maintaining the view state properly. It all depends on whether or not you are setting any properties of the dynamically loaded controls programmatically and, if so, when you’re doing it relative to the
Controls.Add(dynamicControl)
line. A thorough discussion of this is a bit beyond the scope of this article, but the reason it may work is because the
Controls
property’s
Add()
method recursively loads the parent’s view state into its children, even though the load view state stage has passed.

Here you have more information.

EDIT

Just to be sure we’re talking about the same, here you have how your code should look like

protected void Page_Init(object sender, EventArgs e)
{
    ...
    foreach (DataRow dr in drc)
    {
        question = (from ques in bdd.QUESTION where ques.ID_QUESTION == idQuestion select ques).FirstOrDefault();
        List<Object> listParams = new List<Object>();
        listParams.Add(question);
        AdminQuestion qa = (AdminQuestion)(Controller.LoadControl(Page, "~/UserControls/AdminQuestion.ascx", listParams.ToArray()));
        pnl_question_list.Controls.Add(qa);

    }
    ...
}