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.

c# How to utilize Page_init, ViewState and Page_Load properly?

I have been working with Web Forms for a short while now and I have read most of what I have found about this on google. However, I am still unclear on how to work with this properly. I like the picture in this answer, but find it a bit too generic. I have not found one decent, concrete example on how to work with these events.
I am currently creating several controls dynamically in code behind in the Page_Load event:
foreach (Service service in Services)
{
// service div
HtmlGenericControl serviceDiv = new HtmlGenericControl("div");
serviceDiv.ID = service.ID;
serviceDiv.Style.Add(HtmlTextWriterStyle.TextAlign, "center");
outerDiv.Controls.Add(serviceDiv); //outerDiv exists in the aspx page
// service updatepanel
UpdatePanel uPanel = new UpdatePanel()
{
ID = service.ID + "_uPanel",
UpdateMode = UpdatePanelUpdateMode.Conditional
};
serviceDiv.Controls.Add(uPanel);
// status span
HtmlGenericControl statusSpan = new HtmlGenericControl("span");
statusSpan.ID = service.ID + "_statusSpan";
statusSpan.InnerHtml = service.Status;
uPanel.ContentTemplateContainer.Controls.Add(statusSpan);
// show specific content
if (service.Status.Equals(ServiceControllerStatus.Running.ToString()))
{
// status color
statusSpan.Attributes.Add("class", "status-run");
// stop button
HtmlButton stopButton = new HtmlButton();
stopButton.ID = service.ID + "_btnStop";
stopButton.InnerHtml = "<i class=\"fa fa-stop btn-red\"/></i>";
stopButton.Attributes.Add("type", "button");
stopButton.Attributes.Add("runat", "server");
stopButton.Attributes.Add("class", "btn btn-link btn-xs");
stopButton.Attributes.Add("title", "Stop");
stopButton.ServerClick += new EventHandler(BtnStop_Click);
ScriptManager.GetCurrent(this).RegisterAsyncPostBackControl(stopButton);
uPanel.ContentTemplateContainer.Controls.Add(stopButton);
// restart button
HtmlButton restartButton = new HtmlButton();
restartButton.ID = service.ID + "_btnRestart";
restartButton.InnerHtml = "<i class=\"fa fa-refresh btn-blue\"/></i>";
restartButton.Attributes.Add("type", "button");
restartButton.Attributes.Add("runat", "server");
restartButton.Attributes.Add("class", "btn btn-link btn-xs");
restartButton.Attributes.Add("title", "Restart");
restartButton.ServerClick += new EventHandler(BtnRestart_Click);
ScriptManager.GetCurrent(this).RegisterAsyncPostBackControl(restartButton);
uPanel.ContentTemplateContainer.Controls.Add(restartButton);
}
else
{
// status color
statusSpan.Attributes.Add("class", "status-stop");
// start button
HtmlButton startButton = new HtmlButton();
startButton.ID = service.ID + "_btnStart";
startButton.InnerHtml = "<i class=\"fa fa-play btn-green\"/></i>";
startButton.Attributes.Add("type", "button");
startButton.Attributes.Add("runat", "server");
startButton.Attributes.Add("class", "btn btn-link btn-xs");
startButton.Attributes.Add("title", "Start");
startButton.ServerClick += new EventHandler(BtnStart_Click);
ScriptManager.GetCurrent(this).RegisterAsyncPostBackControl(startButton);
uPanel.ContentTemplateContainer.Controls.Add(startButton);
}
// version span
HtmlGenericControl versionSpan = new HtmlGenericControl("span");
versionSpan.ID = service.ID + "_version";
versionSpan.InnerHtml = service.Version;
versionSpan.Attributes.Add("class", "version-text");
serviceDiv.Controls.Add(versionSpan);
What would I gain from creating these in Page_Init? If I create them in Page_Init, how do I access them in Page_Load? Private global lists of UpdatePanels and HtmlButtons feels so unclean.
I know that the ViewState loads between Page_Init and Page_Load, but what does that really mean? Since I don't do full postbacks, but instead use RegisterAsyncPostBackControl to only update the UpdatePanel's on postback, don't I need to re-populate in Page_Load?

If you don't need the ViewState, then you can also create the controls in Page_Load. The ViewState is used to store the values of the controls (which ones depends on the control) and to use them when the PostBack is sent to the server.
For instance, if you have a textbox, the PostBack contains the new value of the textbox and also the old value in the ViewState. The ASP.NET framework now compares those two and raises the TextChanged event if necessary. Without ViewState, this would not be possible.
The best advice you can give regarding dynamically created controls in ASP.NET WebForms is to avoid using them. They increase complexity very fast und are usually not necessary (even if it seems so at first).
In the majority of the cases, there is a much simpler approach, e.g. by using a Repeater. In your case, you have a list of services. You can bind this list to a Repeater and by that avoid to create the controls manually. See this link on how to use a Repeater.
Another upside of using a Repeater is that you can define the UI in the ASPX markup instead of in the code behind file. In your example, you change the UI based upon the status of the service. In this case, using the ItemDataBound-event of the Repeater might be a good option.

Adding EventHandler for dynamically added control

I've got a problem with adding some controls into a Panel(which gets "PopUpped" by a ModalPopupExtender) and add a CheckedChanged-EventHandler.
First of all, when user clicks on a button, this happens inside the CreatePanelChoose() function:
foreach (ListItem item in lbSupplier.Items)
{
string cbid = "cb" + i;
CheckBox cb = new CheckBox();
cb.ID = cbid;
cb.Text = item.Text;
cb.AutoPostBack = true;
AjaxControlToolkit.MutuallyExclusiveCheckBoxExtender mecbe = new AjaxControlToolkit.MutuallyExclusiveCheckBoxExtender();
mecbe.ID = "mecbe" + cbid;
mecbe.TargetControlID = cbid;
mecbe.Key = "SupplierKEY";
mecbe.BehaviorID = mecbe.ID + i;
//Also adding a Label
phModalPopupExtender.Controls.Add(new LiteralControl("</br>")); //phModalPopupExtender is a PlaceHolder
phModalPopupExtender.Controls.Add(cb);
phModalPopupExtender.Controls.Add(mecbe);
phModalPopupExtender.Controls.Add(lbl);
AsyncPostBackTrigger trigger = new AsyncPostBackTrigger();
trigger.ControlID = cbid;
trigger.EventName = "CheckedChanged";
UpdatePanelMatrix.Triggers.Add(trigger);
i++;
ButtonOK.Enabled = false;
}
lblText.Text = "Select one Supplier";
ModalPopupExtender1.Show();
Then i add the EventHandler in the Page_LoadComplete:
As you can see it also gets asigned to the control (I think).
The ModalPopup shows up correctly, but if I click one of the CheckBox, then it just closes it without going into cb_CheckedChanged, but it makes a Async postback ...
If I check Request.Form["__ASYNCPOST"] its true and Request.Form["__EVENTTARGET"] is also correct. (It gives me the unique id!)
Request.Form["__EVENTARGUMENT"] is empty.
I think I also need to say that I use a masterpage.
The problem shouldn't be the lifecycle of the page, because msdn says:
LoadComplete
Raised at the end of the event-handling stage.
Use this event for tasks that require that all other controls on the page be loaded.
Its the onliest place it makes me think it would be right.
Btw: yes i looked trough the topics here allready, but nothing helped me ... (google fo sure also)
Edit 1:
if (IsPostBack)
{
if (recreating == true)
{
CreatePanelChoose();
}
}
In CreatePanelChoose i do the foreach now everytime when its a postback! But it still doesnt fire cb_ChangedChecked ...
Edit 2:
MSDN-Page-Lifecycle also says:
PreInit
Raised after the start stage is complete and before the initialization
stage begins.
Use this event for the following:
Create or re-create dynamic controls.
So i tried to recreate the Panel there. But i dont have the ListItems there to get the values ... ?!

Okay, gave up ...
If someone would still have an answer, it would be great!
Right now I dont use the OnCheckedChanged-Event of the CheckBoxes anymore.
I just let them select a CheckBox and on the OnClick of the ButtonOk I loop through the CheckBoxes and check which one is selected.

ASP.Net rapid button click to add controls in UpdatePanel creates conccurency issue

When I click on a button and add a control to a Placeholder inside an UpdatePanel, everything is fine, except when I click really quickly several times and then get an error message like the following:
'Sys.WebForms.PageRequestManagerServerErrorException: Sys.WebForms.PageRequestManagerServerErrorException: Multiple controls with the same ID 'VehicleRegistrationEnhancedTextBox3_Label' were found. FindControl requires that controls have unique IDs.' when calling method: [nsIDOMEventListener::handleEvent]
[Break On This Error]
I save an integer in a hidden field, to create unique Ids, when I click really fast, the method executes several times, but the count value has not yet updated. I tried using the C# lock keyword, but that did nothing.
The code is below:
protected void AddVehicleButton_Click(object sender, EventArgs e)
{
lock (this)
{
int count = Convert.ToInt32(VehicleRegistrationCountHiddenField.Value);
var TBId = "VehicleRegistrationEnhancedTextBox" + count;
IList<Panel> oldPanels = (IList<Panel>)Session["VehiclePanels"] ?? new List<Panel>();
//Seperator
Literal hr = new Literal { Text = "<hr/>" };
//RemoveSpan
Literal span = new Literal() { Text = "<span class=\"RemoveVehicleRegistration\">X</span>" };
//Crop
Control uc = LoadControl("~/Controls/ImageUploadAndCrop/ImageUploadAndCrop.ascx");
uc.ID = "VehicleRegistrationImageUploadAndCrop" + count;
//Vehicle Registration
Label vehicleRegistration = new Label
{
ID = TBId + "_Label",
AssociatedControlID = TBId,
Text = "Vehicle Registration:"
};
EnhancedTextBox vehicleTypeTextBox = new EnhancedTextBox
{
ID = TBId,
Required = true,
RequiredErrorText = "Vehicle Registration is a required field."
};
//Add new controls to the form
Panel newPanel = new Panel();
newPanel.Controls.Add(hr);
newPanel.Controls.Add(span);
newPanel.Controls.Add(vehicleRegistration);
newPanel.Controls.Add(uc);
newPanel.Controls.Add(vehicleTypeTextBox);
AddVehiclePlaceholder.Controls.Add(newPanel);
//Increment the ID count
count++;
VehicleRegistrationCountHiddenField.Value = count.ToString();
//Save the panel to the Session.
oldPanels.Add(newPanel);
Session["VehiclePanels"] = oldPanels;
//Go back to the same wizard step.
ShowStep2HiddenField.Value = "true";
ShowStep3HiddenField.Value = "false";
}
}

The problem is you are kicking of several postbacks with the same request, then the last response is what's updating your update panel div, causing your issue. One possible solution is to include some javascript to disable your button on click.
<asp:Button ID="myUpdatePanelPostBackButton" runat="server" OnClientClick="this.disabled=true; return true;" Text="Submit" />
Assuming your button is within your UpdatePanel, when the update panel comes back, the button will be re-enabled.

Disabled button will not cause a PostBack. So if you only disable button in OnClientClick, a PostBack will not occur.
Try UseSubmitBehavior="false", it means "anyway cause postback".
<asp:Button runat="server" ID="BtnSubmit"
OnClientClick="this.disabled = true; this.value = 'Submitting...';"
UseSubmitBehavior="false"
OnClick="BtnSubmit_Click"
Text="Submit Me!" />
Refer this blog , it's useful for you.
http://encosia.com/disable-a-button-control-during-postback/

creating RadEditor dynamically asp.net

I want to add RadEditor dynamically. It is getting added to the page but as soon as postback occurs i get Multiple controls with the same ID 'EditorRibbonBarResourcesHolder' were found. Below is the code that i am using to add control dynamically.
RadEditor editor = new RadEditor();
editor.ID = "editor_" + itemTypeattribute.ItemAttributeID + rand.Next();
cellAttributeValue.Controls.Add(editor);
editor.DialogOpener.ID = "editor_dialopOpener_" + itemTypeattribute.ItemAttributeID;
editor.DialogOpener.Window.ID = "editor_dialopOpener_window_"+ ItemTypeattribute.ItemAttributeID;
editor.ClientIDMode = ClientIDMode.AutoID;
editor.EnableEmbeddedScripts = true;
editor.Height = 200;
Any help is appreciated. Thanks

Whenever I need to use a radeditor "dynamically" I have it on the page from the start with visible=false and then show it when I need it.