Develop Reference

C# dynamically created user control button click not working

I have a page (company.aspx) that when you click a button on the page the button click event (btnShowDeptsUserControl_Click) dynamically creates a user control and adds to a placeholder. The page reloads with the user control displayed. That works fine.
The issue I am having is that when I click the button on the user control itself, the btnEmailDepts_Click event is not fired, but the main page (company.aspx) is reloaded.
I have read that one way to resolve this is to create the dynamic user control in Page_Init, but I am creating the user control from the main page button click. Also, I am not declaring the user control in the code behind of the main page as you would normally, but do have a placehoder within which the user control is added.
I have also read that you can add a delegate to the main page for the user control button click, but the example seemed to have so much necessary code for such a simple thing that I figured there must be a better way.
Here are the relevant code snippets:
company.aspx:
<asp:Button id="btnShowDeptsUserControl" runat="server" OnClick="btnShowDeptsUserControl_Click">Show Depts</asp:Button>
<asp:PlaceHolder ID="phUserControls" runat="server"></asp:PlaceHolder>
company.aspx.cs:
protected void btnShowDeptsUserControl_Click(object sender, EventArgs e)
{
CreateDeptsUserControl();
}
private void CreateDeptsUserControl()
{
phUserControls.Controls.Clear();
var uc = (UserControl)LoadControl("~/controls/ucDepartments.ascx");
phUserControls.Controls.Add(uc);
}
ucDepartments.ascx:
<asp:Button ID="btnEmailDepts" runat="server" Text="Send Email" OnClick="btnEmailDepts_Click" />
ucDepartments.ascx.cs:
protected void btnEmailDepts_Click(object sender, EventArgs e)
{
EmailDepts(); // breakpoint here is never hit
}
private void EmailDepts()
{
// do something
}

If you read the MSDN, you will notice:
However, the added control does not catch up with postback data processing. For an added control to participate in postback data processing, including validation, the control must be added in the Init event rather than in the Load event.
You are adding your control in the click event which happens after both init and load events, so the postback will not work.
You can call your CreateDeptsUserControl function in the ini event, but there you will have to detect if the btnShowDeptsUserControl was clicked by yourself. It's not hard, you will need to check the submitted values collection and see if there is an item for btnShowDeptsUserControl.

Just wanted to post what I did to make this work. Racil Hilan's answer helped me to arrive at this solution. I did away with the dynamic user control, and went with the more common declared user control in the aspx, but set it to Visible="False" by default.
Notice that the main page button event is empty. Also notice that the user control Page_Load event is empty. All the checking is done in the user control OnInit event, which is executed with each main page load.
In the user control OnInit event I have a couple guard conditions that check to see what EVENTTARGET, if any, caused the page / user control to load. If the EVENTTARGET (control ID) is that of the main page button, then execution will continue and will call LoadSomeData() as well as set the user control Visible = true. Otherwise, if either guard condition evaluates as false, we exit and the user control does not get loaded, so no wasted db / service calls.
company.aspx:
<asp:Button id="btnShowDeptsUserControl" runat="server" OnClick="btnShowDeptsUserControl_Click">Show Depts</asp:Button>
<uc1:ucDepartments ID="ucDepartments" runat="server" Visible="False" />
company.aspx.cs:
protected void btnShowDeptsUserControl_Click(object sender, EventArgs e)
{
// empty, just need the event for inspection later in user control OnInit event.
}
ucDepartments.ascx:
<asp:Button ID="btnEmailDepts" runat="server" Text="Send Email" OnClick="btnEmailDepts_Click" />
ucDepartments.ascx.cs:
protected override void OnInit(EventArgs e)
{
if (string.IsNullOrWhiteSpace(Request.Params["__EVENTTARGET"]))
return;
var controlName = Request.Params["__EVENTTARGET"];
if (controlName != "btnShowDeptsUserControl")
return;
LoadSomeData(); // call method to load the user control
this.Visible = true;
}
protected void Page_Load(object sender, EventArgs e)
{
// empty
}
private void LoadSomeData()
{
// get data from database
// load table / gridview / etc
// make service call
}
protected void btnEmailDepts_Click(object sender, EventArgs e)
{
EmailDepts(); // this event is now executed when the button is clicked
}
private void EmailDepts()
{
// do something
}
Variation that includes jquery to scroll to user control after postback:
In the main page button click event you can also do something like set a hidden var to a value that can be inspected on main page doc ready to do some jquery stuff, such as scrolling the user control into view if it is far down the page (which I am actually doing in my current task).
Not only will this scroll the now loaded user control into view after clicking the main page button, but notice the code in setupDepts(). I hide the asp button that does a postback to load the user control, and show a regular html button. They both look the same (both say Show Depts), but the regular html button, when clicked, will fire jquery to toggle the div that contains the user control to close, click again, it will open, click again it will close, etc.
This is so that you only load the user control once (make db / service calls once) when the main page button is clicked, and then can toggle show or hide it with subsequent clicks of the alternate button. This approach can be used with multiple buttons or links so long as they all have the same class ids. For example, you may have a Show Depts button / link at top of page and another at the bottom of the page, which is the case in my current task.
company.aspx:
<asp:Button id="btnShowDeptsUserControl" runat="server" class="btnShowDepts" OnClick="btnShowDeptsUserControl_Click">Show Depts</asp:Button>
<button class="btnToggleDepts" style="display: none;">Show Depts</button>
<div id="divShowDepts" style="display: none;">
<asp:HiddenField runat="server" id="hdnShowDepts"/>
<uc1:ucDepartments ID="ucDepartments" runat="server" Visible="False" />
</div>
<script language="javascript" type="text/javascript">
$(function () {
toggleDeptsUserControl();
if ($('#<%=hdnShowDepts.ClientID%>').val() === "show")
setupDepts();
});
function setupDepts() {
$('.btnShowDeptsUserControl').hide();
$('.btnToggleDeptsUserControl').show();
scrollToDepts();
}
function scrollToDepts() {
$('#divShowDepts').toggle(700, function () {
if ($(this).is(":visible")) {
$('html, body').animate({ scrollTop: ($(this).offset().top) }, 'slow');
}
});
}
function toggleDeptsUserControl() {
$('.btnToggleDeptsUserControl').on('click', function (event) {
event.preventDefault();
scrollToDepts();
});
}
</script>
company.aspx.cs:
protected void btnShowDeptsUserControl_Click(object sender, EventArgs e)
{
hdnShowDepts.Value = "show";
}

ASP.NET Click event does not work for multi buttons what created in tab button control

I am new in ASP.NET and I have a problem..
In my code, btn.Click event does not work for multi buttons what created in tab button control. Can you guys advice me?
Thanks,
<asp:Button Text="TAB MENU" BorderStyle="None" ID="Tab" CssClass="Initial" runat="server" OnClick="Tab_Click" />
<asp:Panel ID="panel1" runat="server" Direction="LeftToRight" HorizontalAlign="Left"></asp:Panel>
protected void Tab_Click(object sender, EventArgs e) {
foreach (...) {
Button btn = new Button();
btn.Click += Button1_Click;
panel1.Controls.Add(btn);
}
}
protected void Button1_Click(object sender, EventArgs e) {
**some code here! but does not work.**
}

Try this
Button btn = new Button();
btn.Click += new RoutedEventHandler(Button1_Click);
panel1.Controls.Add(btn);

Your problem probably lies along the lines of the fact that the button does not exist when the Button1_Click callback is fired... Asp.net webforms is a somewhat leaky abstraction over HTTP, and therefore it's a bit tough to decipher sometimes, but I expect what is happening is that when the postback from your button click occurs, the button doesn't actually EXIST in the control tree, because that button only gets added to the control tree when a tab control is clicked. So because the button does not exist on the postback, webforms doesn't know what to do with the event, so it ignores it...
If your buttons must be created dynamically, consider making them do some javascript to edit some hidden field or something, the value of which you can inspect in the Page_Load method, and then do whatever you want to do functionality-wise with that value.
If they are NOT dynamic, and instead will be the same for each page load (but different for each tab - ie, when the page is loaded, you're drawing some info from a db to decide what buttons to display, but that will not change from postback to postback of the same page), then consider creating the buttons in the Page_Load event instead of inside the event that is raised when the tab is created.
ALTERNATIVELY, since in your comment you suggest that the buttons will be used to open a new window, why not just make the buttons do that client side, ie with javascript window.open commands. Then you don't even need to postback to the server at all...

Button not firing in user control

I currently have a master page that has a drop down menu which displays a different User control depending on the menu choice.
Inside of the User control I'm trying to add a submit button that processes the inputted forms inside the user controls using the "_Click()" event handler. My user control aspx looks like the following:
<asp:Button ID="configBttn" runat="server" OnClick="configBttn_Click" AutoEventWireUp="true" />
and then I have the following in the codebehind:
protected void Page_Load(object sender, EventArgs e)
{
}
protected void configBttn_Click(object sender, EventArgs e)
{
Response.Write("Hello world");
}
I have even tried to add an event handler:
configBttn.Click += new EventHandler(configBttn_Click)
However this is still not allowing for the button to be triggered. Any ideas?
I add the user control inside the codebehind inside a div container:
divContainer.Controls.Add(pPage.LoadControl("~/Controls/Control.ascx"));

Where are you creating the UserControl in the Page Lifecycle?
I suspect that it needs to be created in the Init method of its container page.
In addition, they should not be wrapped in a !IsPostback block, or else when the page posts back, the control event handler is not mapped, so nothing is there to catch the click event.

Without seeing the code that adds the user control, I'm guessing that it is not saved as part of the page's view state. Which means when you click the button inside the user control the whole page gets refreshed and the user control is either not created or a different instance of it is created.

onClick event is not working for user control controls

I'm loading an user control in one of the class file. This is not code behind page. This is common class for grid view which is applied to all the gridviews in all pages.
I added onclick method to the controls in the user control, but they are not firing in the code behind of that user control.
I kept break points. However, it is not reaching those break points. In addition, the user control is getting closed after I click on any control which has onclick method. After clicking the entire page is reloading in which the grid view is loaded and because of it i guess user control is disappearing. I used update panel in user control still it is not working. Onclicking the the user control is going inside on_pageload of that user control.
This user control is displayed when an image on each column of grid header is clicked. My code is as follows
User control ASCX:
<asp:LinkButton ID="lnkSortDescending" runat="server"
onclick="lnkSortDescending_Click">
Sort Descending
</asp:LinkButton>
Code Behind:
protected void lnkSortDescending_Click(object sender, EventArgs e)
{
//some code
}
File in which user control is loaded:
protected void btnFilterButton_Click(object sender, ImageClickEventArgs e)
{
int i = 0;
Panel p = new Panel();
Control uc = (Control)Page.LoadControl("~/UserControls/FilterPanel.ascx");
uc.ID = "Filter"+(i++);
p.Controls.Add(uc);
}
Please help me to solve this problem.

AjaxToolkit Tab Control as Button

I am currently building a tab control with multiple tab panels, and would like to have one of the tabs as a button instead of a template with content. The idea being that when the user clicks on the tab with the button, an event would fire and a C# method would run, and the page would post back.
How would I go about doing this? Preferably this could be something generated in the code behind as all the other tabs are programmatically generated along with the content.

You can handle TabContainer's ActiveTabChanged event. Therefore you need to set AutoPostBack for the TabContainer to true.
<asp:TabContainer ID="TabContainer1" runat="server" AutoPostBack="true" OnActiveTabChanged="ActiveTabChanged">
Codebehind:
protected void ActiveTabChanged(object sender, EventArgs e)
{
if (TabContainer1.ActiveTabIndex == 0)
{
// ...
}
// ...
}