Develop Reference

Dynamic ModalPopupExtender not firing the OK Click event

ASP.NET 4.7.2 Web Forms c# VS 2019
I am trying to use a modalpopupextender to prompt for new data for foreign key fields. Like the form itself, the MPE is built on the fly in code -- in this case the click handler for the hidden button that the Javascript fires off to build and show the MPE.
I read every single article on SO and the ASP forums and tried everything I saw there. No joy. I get the popup perfectly. Hitting OK closes the popup, but never fires the OK Event.
Here is the code:
//Building the form, we do this in OnInit:
// AJAX Update Panel
UpdatePanel PUP = new UpdatePanel()
{
ID = "PUP",
};
PlaceHolder.Controls.Add(PUP);
// HiddenField containing the field name to permit
// creating the correct modalpopup.
HiddenField HFPopupField = new HiddenField()
{
ID = "HF_POPUP"
};
PUP.ContentTemplateContainer.Controls.Add(HFPopupField);
// Create Hidden button to track the popup
Button BPopup = new Button()
{
ID = "BPOPUP",
UseSubmitBehavior = false
};
BPopup.Click += BPopup_Click;
BPopup.Attributes.Add("style", "display: none;");
PUP.ContentTemplateContainer.Controls.Add(BPopup);
// And create the background panel for the popup.
Panel PnlPopup = new Panel()
{
ID = "PNLPOPUP",
CssClass = "MpeBackground"
};
PnlPopup.Attributes.Add("style", "display: none;");
PUP.ContentTemplateContainer.Controls.Add(PnlPopup);
/// Event handler for hidden button.
protected void BPopup_Click(object sender, EventArgs e)
{
[snip -- code to get the dataset that is being filled]
UpdatePanel PUP = Placeholder.FindControlRecursive("PUP");
Table T = new Table()
{
CssClass = "PopupTbl"
};
TableRow TRTitle = new TableRow();
TableCell TCTitle = new TableCell()
{
CssClass = "PopupTitle",
ColumnSpan = 2
};
Label LPopTitle = new Label()
{
Text = [title of the popup]
};
TCTitle.Controls.Add(LPopTitle);
TRTitle.Cells.Add(TCTitle);
DataRow drData = null;
// Add Fields, and also the cancel and Add buttons
foreach (DataColumn DC in dsColumns.Tables[0].Columns)
{
TableRow TRColumn = [create a tablerow with 2 columns, a prompt and the input field]
if (TRColumn != null)
{
T.Rows.Add(TRColumn);
[snip]
}
} // end of foreach(DataColumn DC in dsColumns.Tables[0].Columns)
PnlWindow.Controls.Add(T);
TableRow TRButtons = new TableRow();
TableCell TCButtons = new TableCell()
{
ColumnSpan = 2,
CssClass="PopupButtons"
};
Button MPEBOK = new Button()
{
ID = "MPE" + sFieldName + "_MPEBOK",
Text = "OK",
CausesValidation = false,
UseSubmitBehavior = false
};
MPEBOK.Click += MPEBOK_Clicked;
TCButtons.Controls.Add(MPEBOK);
LiteralControl LCB = new LiteralControl()
{
Text = " "
};
TCButtons.Controls.Add(LCB);
//************************************************************
//*** Postback Trigger ***
//************************************************************
AsyncPostBackTrigger trigger = new AsyncPostBackTrigger()
{
ControlID = MPEBOK.ID,
EventName = "click"
};
PUP.Triggers.Add(trigger);
//************************************************************
//*** Cancel Button ***
//************************************************************
Button MPEBuhBye = new Button()
{
ID = "MPE" + sFieldName + "_BUHBYE",
Text = "Cancel",
UseSubmitBehavior = false
};
TCButtons.Controls.Add(MPEBuhBye);
TRButtons.Cells.Add(TCButtons);
T.Rows.Add(TRButtons);
PnlPopup.Controls.Add(PnlWindow);
AjaxControlToolkit.ModalPopupExtender MPE = new AjaxControlToolkit.ModalPopupExtender()
{
ID = "MPE" + sFieldName,
PopupControlID = "PNLPOPUP",
TargetControlID = "BPOPUP",
BackgroundCssClass = "MpeBackground"
};
// Add the MPE to the UpdatePanel.
PUP.ContentTemplateContainer.Controls.Add(MPE);
// Show the modal popup extender.
MPE.Show();
}
protected void MPEBOK_Clicked(object sender, EventArgs e)
{
[snip - this never fires]
}
I cannot find out what is happening here. Can anyone see something hinky?
Thanks
John.

You can't add a server side button or inject a server side button into the page DOM.
When you drag a asp.net button onto the form, BOTH the "mypage.cs" and mypage.desinger.cs ARE updated. The wire up of the button occurs at design time, and you would have to modify mypage.desinger.cs ALSO and ADD a button event stub.
So you can't do this.
A compromise would be to also add some js and have that HTML button execute a .click() method of a hidden asp.net button you drop into that page (that would give you the post back, and the running behind of a separate button event code stub.
This event resolution occurs at compile time - not at page render time. You have to drop that button onto the page.
I suppose you could adopt a standard that you always place right below that "div" on the page the button (hidden with style=none. And then as noted, have your injected code along with some js execute a click on the hidden button. Or just have the js button code execute a __doPostback("some value") and pick this up in the page on-load event, and then call the routine (function) from on-page load event.
I think better would be to use a jQuery.UI dialog, as that dialog CAN say load + use another different web page into a “div” on the existing page. So you layout, make, and create the nice looking popup form as a separate web page. jQuery is able to remove the “form” and additonal tags out of that page load, and then inject it into the existing page. (that code would be rather hard to re-produce). so jQuery.UI is able to pop up that separate page. however, the buttons on that loaded page (into that div) of course can't really run any code behind in the current page. However, the buttons CAN run local js in the current page. Thus the actions of this injected page would be local to each page. But the popup would not be directly calling a code behind stub.
Now, to adopt jQuery.UI, then you also have to of course adopt jQuery. So that is two extra libraries you need. (but, jQuery you likely already have).
However, I suppose the whole point of using the ajax toolkit is to avoid jQuery.ui in the first place. To be fair, before jQuery.ui came along, that tool kit was REALLY impressive, and gave asp.net folks a REAL leg up on the competition. (and it tends to be MUCH less wiring up then say using jQuery.UI
So the AjaxToolkit in its heyday was impressive. Now, it of course showing its age, but I still use the kit, and this is especially the case for the AjaxFileUploader. And yes I do use the popups – even to this day. However, I find now that jQuery.UI dialogs are more flexible, and would be better in this case (because you want a on-the fly setup).
Also, having code behind buttons in even the jQuery.UI dialog, or in this case the ajax popup? Well, only the action button can run code behind. The cancel button of course will just dismiss the dialog. However, any button in the dialog that WILL run code behind? Well, that's ok, since you have a page post back, and it actually the page postback that BLOWS out the dialog anyway.

How to trigger a created checkbox change event c#

I created these checkboxes in my gridview to allows my users to select several rows. My problem is when the checkboxes are clicked they are suppose to store info for each one clicked. I placed breakpoints inside and the event is never triggered. Is this something I need to call in order to have this event run? I was under the impression it was like any other event where it just ran upon triggering it. I haven't found a generic help for these type of issue, it seems to be more specific problems. Do you have nay reference to help or any suggestions on how to allow my event to trigger properly?
On form load this is established
ckBox = new CheckBox();
//Get the column header cell bounds
Rectangle rect = this.dropdeadGridView.GetCellDisplayRectangle(0, -1, true);
ckBox.Size = new Size(18, 18);
//Change the location of the CheckBox to make it stay on the header
ckBox.Location = rect.Location;
ckBox.CheckedChanged += new EventHandler(ckBox_CheckedChanged);
//Add the CheckBox into the DataGridView
this.dropdeadGridView.Controls.Add(ckBox);
Then this is where I declare what happens in the chkbox_CheckChanged Event
var rows = dropdeadGridView.Rows;
for (int j = 0; j < this.dropdeadGridView.RowCount; j++)
{
this.dropdeadGridView[0, j].Value = this.ckBox.Checked;
bool checkBoxValue = Convert.ToBoolean(dropdeadGridView.Rows[5].Cells[1].Value);
if (checkBoxValue)
{
values += rows[j].Cells[2] + ",";
CurrentOrders = values;
}
}
this.dropdeadGridView.EndEdit();

Hope you are using a windows application
http://csharp.net-informations.com/datagridview/csharp-datagridview-checkbox.htm
this link is telling how to add checkboxes in gridview. When changing selection the grids events like afteredit,validateedit etc will fire.
We are coding at there by checking the column number(if the column number matches with check box column number) do the operations which you mentioned in event at there
I'm less experianced in winforms and i used C1FlexGrid only(Equivalent will be there in windows grid also)

Add an unhook event call, before hooking the event.
ckBox.CheckedChanged -= new EventHandler(ckBox_CheckedChanged);
Mostly your problem will get solved

Why dynamically created Radmenu ItemClick event is not firing

I am dynamically creating a RadMenu. I want to use the menu click event of the RadMenu.
Actually I am using if(!Scriptmanager.IsInAsyncPostBack) condition.
Within the if condition I only write code to create the menu dynamically. I'll give the sample code for better understanding.
if (!src.IsInAsyncPostBack)
{
RadMenu menu = new RadMenu();
RadMenuItem item1 = new RadMenuItem();
item1.Text = "Home";
RadMenuItem item11 = new RadMenuItem();
item11.Text = "Home";
item1.Items.Add(item11);
RadMenuItem item2 = new RadMenuItem();
item2.Text = "About";
RadMenuItem item3 = new RadMenuItem();
item3.Text = "Contact";
menu.ItemClick += new RadMenuEventHandler(menu_ItemClick);
menu.Items.Add(item1);
menu.Items.Add(item2);
menu.Items.Add(item3);
Page.Controls.Add(menu);
}
void menu_ItemClick(object sender, RadMenuEventArgs e)
{
Response.Redirect("Home.aspx");
}
When page loading if(!IsInAsyncPostBack) condition true so the RadMenu is created dynamically and loaded in the page.
When I click the menu item, Postback becomes true, so the if condition fails and the menu
click event is not firing.
I wrote the menu click event outside of the if condition. In this case the menu click event is also not firing.
My exact requirement is that I want to use if(!IsInAsyncPostBack) postback condition as well as I need to use menu click event. Is it possible?

Add this in the Page_Init event and remove the if (!src.IsInAsyncPostBack) check. THis is the easiest way to create controls programmatically.
Probably your menu is ajax-enabled so a POST from it is partial, so your code does not recreate it, so it cannot raise its handler.

Reading __EVENTTARGET causes event is not called

I want to use information on which control was clicked for setting up the page. I use this to set up a sortable table in code. I found through this forum that I can use Request.Form.Get("__EVENTTARGET") for that. However, as soon as I do something with that parameter, the callback function is no longer called. Is this expected behavior or am I making a mistake?
Here some snippets of my code. The code in Page_Load() is:
string sortRequest = Request.Form.Get("__EVENTTARGET");
bool isCurrentField = false;
if (sortRequest != null) isCurrentField = sortRequest.Contains(header.Field);
if (!isCurrentField)
{
// Add a hyperlink for sorting to the cell
LinkButton newLink = new LinkButton();
newLink.Text = header.Title;
newLink.Font.Bold = true;
newLink.ID = "link" + header.Field;
newLink.CommandName = "Sort";
newLink.CommandArgument = header.Field;
newLink.Command += new CommandEventHandler(LinkButton_Command);
hdrCell.Controls.Add(newLink);
}
else
{
hdrCell.Text = header.Title;
hdrCell.Font.Bold = true;
}
My callback:
public void LinkButton_Command(Object sender, CommandEventArgs e)
{
_sortOrder = e.CommandArgument.ToString();
}
I have also tried it with copying the sortRequest into a temporary variable, but that doesn't make a difference. As soon as I comment out the line if (sortRequest != null) isCurrentField = sortRequest.Contains(header.Field);, the callback is called again.

There is a fault in your logic. You have a dynamically created control LinkButton with LinkButton_Command event handler connected to it. For the server-side event to fire on postback, the control must be present in the page control tree. This means the dynamic LinkButton must be created, configured and added to hdrCell.Controls always, regardless of sortRequest value. Only then will it be able to pick up the fact that it was clicked from the Request and fire its Command event.

Get values from dynamic controls with c#?

I created a few radiobuttonlist controls on my project, they're created every time the page is loaded, i want to get the value of the radiobutton that the user has selected, but since my radiobuttons were created dynamically, i don't know how to acces to their values nor how to create their event handlers. Is there a way to assign a name or id to the control when i create it?
i hope you can help me.
I create a seires of radiobuttlist on the page_load event, with the text and their values been pulled out of a database. now, the user has to choose one of the options from that radiobuttlist and i want to get the value of the radiobutton the user checked. how do i do that if i don't know the name nor the id of the radiobuttlist since they're created dynamically.
this is what i've got:
for (int i = 3; i < numfields; i++) {
if (dr[i].ToString() != "" && dr[i] != null){
r.Items.Add(new ListItem(dr[i].ToString(), dr[i].ToString()));
//r.SelectedIndexChanged += new EventHandler(rowSelectedIndex);
}
}
so basically i use my datareader to loop through the data in the database, if the value from the field isn't empty or null, then i add an item to the radiobuttlist called "r"
i tried to create an eventhandler for that too, but since i have never worked with them i really don't know what to do. :(
I'm so sorry if i seem way too pathetic.

Taking a quick look at your code:
for (int i = 3; i < numfields; i++) {
if (dr[i].ToString() != "" && dr[i] != null){
r.Items.Add(new ListItem(dr[i].ToString(), dr[i].ToString()));
//r.SelectedIndexChanged += new EventHandler(rowSelectedIndex);
}
}
The most obvious thing that jumps out is your if statement. You should first check for null:
if (dr[i] != null && dr[i].ToString() != ""){
As if dr[i] is null, you'll get an exception (as you'll be trying to call the ToString() method on a null object.
If the contents of dr are always going to be strings, you might consider writing:
if(!String.IsNullOrEmpty(dr[i]){
I also note you start your indexing at 3 - is this because you want to skip the first 3 fields?
Wherever you create your variable, 'r', you can set the name and ID properties. You can use the ID property to look for the control on PostBack. So if you created your radiolist like so:
RadioButtonList r = new RadioButtonList();
r.Id = "MyRadioButtonList";
r.SelectedIndexChanged += MyRadioButton_SelectedIndexChanged;
Which would point at the following event handler:
private void MyRadioButton_SelectedIndexChanged(Object sender, EventArgs e) {
... Do Stuff ...
}
There are several ways of finding your control when you post back; you can look in the Request.Forms collection for a control matching the name of the control you submitted, or, more appropriately, you can use the FindControl method with the ID you gave the control. See C#, FindControl for a post with a method (by Jeff Atwood!) that will search the entire hierarchy of controls for your control.
When you add a dynamic control is important, too. If you add it too late in the page lifecycle then it will not be available on PostBack. See http://support.microsoft.com/kb/317515 for more details on just when to add a control. There are plenty of resources for Dynamic ASP.Net controls around too.

You could put your RadioButton into a list as you create them. This is also when you want to add your handlers.
RadioButton rb;
for (int i = 1; i < 5; i++)
{
rb = new RadioButton();
rb.AutoSize = true;
rb.Location = new System.Drawing.Point(25, (i*25) + 25);
rb.Name = "radioButton" + i.ToString();
rb.Text = "radioButton" + i.ToString();
//Add some event handler?
this.Controls.Add(rb);
lstRadioButton.Add(rb);
}
Whenever you want to know which one is selected you can do a foreach loop of your list and look if your RadioButton is checked.
foreach (RadioButton rButton in lstRadioButton)
{
if (rButton.Checked == true)
{
//Do something
}
}

You are maybe searching for TagName property if the programmatic name isn't enough for you.

The problem is that you are creating the controls in page_load. In order for their values to be posted back into the controls correctly, you must move this creation into the page_init method and recreate them every time.
Then, in page_load, you can access the values in the controls correctly. If you give them IDs using a consistent naming convention, you will be able to find them using the FindControl method or, in page_init, you can store them in a collection at the page or user control level.