Got a very "Schrodinger's Cat" moment going on right now.
First, some background on my setup. Most of this is probably irrelevant, but, for completeness, I'm providing it. I'm using a .NET 4.6.2 WebForm (.ASPX page) with a MasterPage. The MasterPage is contained within another MasterPage. Within the WebForm I have an UpdatePanel (UpdateMode = Conditional). Inside the UpdatePanel I have another UpdatePanel (also with UpdateMode = Conditional). Inside that inner UpdatePanel, I have a Repeater and a Button. The Repeater is bound during the Page_Load event of the WebForm, and within a !Page.IsPostBack block. The Button has a Click event that accesses the Repeater.Items Collection.
For some reason, when the Button is Clicked, on PostBack, if the Repeater.Controls Collection is accessed at any time before Page_Load, the Collection becomes emptied. I've tried to figure out at exactly what point the Collection is filled on PostBack, but it seems to be happening somewhere inside the System.Web.dll file, and I can't seem to debug inside that (an unrelated, but frustrating issue).
To simulate this, I've done the following:
1) Added an empty handler for the Repeater.ItemCreated event and put a breakpoint within this event
2) Put a breakpoint on the Page_Init event of the WebForm
3) Added a debugger watch for the Repeater.HasControls() method
When the page is first loaded and the Page_Init breakpoint is hit, the Repeater.HasControls() method properly evaluates as false. During the Page_Load event, since this is not a PostBack, the Repeater is bound, and the Repeater.ItemCreated and the Repeater.ItemDataBound events are fired once for each row created in the Repeater.
When the Button is clicked, a PostBack occurs. When the Page_Init breakpoint is hit, the Repeater.HasControls() method again evaluates as false. If I do nothing else, the next event that fires is the Repeater.ItemCreated event, once for each row - this time around, the Repeater.ItemDataBound event doesn't fire, which is normal, since the Repeater is not being rebound on PostBack (and, for that matter, we haven't reached the Page_Load event either way). Next, the Button Click event is evaluated, and it properly loops through the Repeater.Items Collection. All good.
However, if, during this Button Click PostBack Page Init event, instead of simply evaluating the Repeater.HasControls() method, I access the Repeater.Controls Collection - IE, I put a code block that checks Repeater.Controls, I put a watch on Repeater.Controls, or I even just do a quick watch on Repeater.Controls, the Repeater.ItemCreated event no longer fires. When the Button Click event is evaluated and it tries looping through the Repeater.Items Collection, the Collection is now empty.
I've tried everything I can think of to figure out why this is happening, and have had no success. If anyone has any suggestions on more things I can test for, places I can search, or whatever, I'd love some advice.
Thanks in advance!
Related
I have stepped through my code, and it stops when the page is fully loaded, as it should. However, their are a few buttons on the page, that I DO NOT see the names of in my code, so I can't discover where to add a breakpoint to, to follow the logical flow. How can I see what is happening, 'behind the scenes' when one of those buttons is pressed?
EDIT---Would this be an applicable scenario to use tracing?
If you add a Page_Load event to the WebForm, you can put a breakpoint there. That event / method will be called every time there is a server-side interaction with any of the controls on the page, followed by the button click (or whatever other interaction is occurring). When on that breakpoint during a PostBack, you can look at the Form["__EventTarget"] value to determine what control is being invoked and the Form["__EventArgument"] may contain additional details on what event is being triggered.
Okay,
I have this scenario:
There is a user control with an update panel within it. There is a button within that update panel with proper postback trigger being set. The button_click event is also defined well. I need to call a full postback of the parent aspx page once the "button_click" event is completed. Under ideal case, all the form submission events such as postbacks occur before event based methods are executed. This means my page will first be reloaded then the button click event will be executed. I want something like to reverse this operation. First Button_click event execution then one postback after that on the aspx page(this page calls the user control-> and this user control has the updatepanel with button in it).
Any possible way out would be highly appreciated.
I don't think there's a way to change ASP.NET's lifecycle, like the one you described. A (dirty) way of postbacking the parent page is however to put a hidden button on that page, and call it via javascript in the UC. (via ScriptManager.RegisterStartupScript)
I'm developing simple WebForms application, where I'm trying to catch simple click event of Button ASP.NET Control from the UpdatePanel.
Button wasn't added in MarkUp part of project. It was added dynamically from the CodeBehind and also event was added dynamically too to the static class.
Here is code:
http://ideone.com/bnntkb (CodeBehind only, because MarkUp holds just only the ScriptManager and UpdatePanel controls ).
First of all, I think the issue related to the Page.IsPostback and I have tried to use:
if (Page.IsPostBack) PageSetup();
But nothing happens, it just not firing the .Click event either.
Why do I have such a problem and how to fix it?
Thanks!
Please see what happens when you put PageSetup() into the Page Init procedure. Dynamically created controls are supposed to be created there.
Maybe some UpdatePanel initialization takes place earlier in the Page Life Cycle.
Also, dynamically created controls must be created each time the Page is created, even in PostBacks.
I have a user control that I am explicitly calling from an aspx page. In page_load of the aspx page I have the following:
myControl = (DynamicTable)Page.LoadControl("../inc/DynamicTable.ascx");
Then in my code where I want it to execute the control, I have this:
pnlESDDEnrolled.Controls.Add(myControl);
where pnlESDDEnrolled is the panel I am loading it into for display.
So, I execute the aspx page, it links off to the user control, populates the control, returns back to the aspx page and the page displays with the user control in the middle of it. All is well.
The problem comes in when updates are made on the user control. Keep in mind, that other data is updated on the page as well, and the update button resides on the page, not the control. Anyway, when the update button is pushed, the button_click event is fired on the page, but the updates that I made on the user control are lost. Since the page loaded the user control and then the usercontrol executed the page unload method, the page has no knowledge of the user control anymore. Thus, when the update button on the page is pushed, I guess I am not really sure what happens with the updated data on the user control. All I know is that it is lost. I have been working on this for a huge amount of time, any help would be much appreciated
You need to check for IsPostBack in your user control, too.
As your page loads, the Page's Page_Load event starts, then your UserControl's Page_Load will begin, execute, then its events, then controls returns to the page's Page_Load, then all of its events. Of course, if you are using Pre_Init on the page or overriding OnInit in your controls, those events execute before the Page_Load.
So, if you are dynamically creating items on your UserControl, check for IsPostBack and places those events an override OnInit function in the UserControl. Then add your programmatic reference to that UserControl in the Page_Init of the page.
I guess while you're talking about user control state these are realised as Properties in the code?
If so, then you're probably going to have to use Viewstate to persist the UserControl's state so that when the page comes back, the UserControl will be re-populated first with what it previously had when it was being rendered. This is as simple as changing any public state properties to use ViewState as the backer.
I'm not a great fan of viewstate, but sometimes it has to be used.
However there may be more at work here - as your instincts are telling you, this might also be a problem with the fact that this usercontrol is loaded dynamically.
In which case, it all depends at which part of the page lifecycle you're doing it. You need to get this control into the page's tree before render (pre-render might be possible), as it's at this point that that page 'captures' its controls collection for the purposes of maintaining state.
Try and move the insertion of this control into the page structure as early as you can in the lifecycle. The earlier the better - so Page_load would be fine.
Equally - it might be you're already doing this - in which case I'd need more information (perhaps a reproducable scenario) in order to help fix it.
When a button is clicked, I would like to check whether a button is clicked in my page_load. Is this possible? I am using asp.net 2.0 C#
You can check the IsPostBack flag to see if it was a postback rather than an initial load. This may be what you're after. Also, you can check the Request.Form["__EVENTTARGET"] from which you can obtain information about the control that raised the event and therefore find out if it was one of your buttons from there.
The button click event will fire after the page load event has. That being said, you can always check the http header to see what value is being pushed back through the request.form event. The button id will be in there if it has been fired.
I can think a work around by creating a hidden field and changing the value when a certain button is clicked and checking it value in Page_Load.