I have a page with several user controls in different updatepanels. The user controls includes jquery calls which are used to calculate some values and draw graphs(no server methods are called from jquery).
The problem is that, whatever updatepanel is refreshed, all of the jquery calls are processed again. I think the problem arises because i use pageload methods of the usercontrols to do jquery method calls.
I wonder whether there is a way to stop other user controls from calling their pageload methods or refreshing.
thanks in advance.
maybe this would help...not exactly an answer
when you include custom controls on a page on rendering the controls HTML is included in the page as it is with all JavaScript and css( you can do a View page Source) and check that.
and so in effect there can be 3 pageloads in your page(the page that has the user controls included) in different tags and as such all are getting called when any update panel refreshes.
Related
I am adding RadDock control and adding its Item Command events which require to be added in Pag_Init. And adding user controls to RadDock.
My problem is that when I have some post back for a specific control page_Init calls which reloads the controls and every control is re-binded every time. I want to avoid control creation every time. And want the specific control's post back should happen.
If I apply (!IsPostBack) condition in Page_Init then controls are not loaded and page gets empty.
I am stuck.
Any best practice or work around is acceptable.
Thanks in advance.
I don't know the specifics of Telerik's tools, but if they work like regular ASP.NET dynamic controls, you have to add the controls to the control tree on every page load. Populating the controls with data is distinct from adding them to the control tree. If the controls are added correctly so that they are placed in the same way in the control tree as on the previous page visit, and implement ViewState correctly (if needed) the runtime will populate them with data from the posted data and ViewState when a postback occurs.
I added IFrame to RadDock and then gave user control source to IFrame. Now it is working fine, Only the specific control's post back occurs.
Any way, Thanks Jonas
I'm working on developing a custom control to select items from a predefined list. This is accomplished via 2 ASP.NET ListBox controls, with a few buttons to trigger the movement of ListItems from one ListBox to the other (lets call these ListBoxes lstSelected and lstDeselected).
This is easy enough to do in ASP.NET or JavaScript independently: I have both working. However, if modifications are made via JavaScript, ASP.NET retains no knowledge of this. Is there any way to register the creation of of options in a select tag without AJAX?
You could also do this with traditional postbacks, it doesn't have to be ajax. The postbacks would be triggered by clicking your buttons which change which items are in which listboxes.
You could have a couple of hidden fields, say hdnHasSelectedChanged and hdnHasDeselectedChanged, and set those fields in your javascript code. Then, when a postback really happens, your code-behind can read those hidden fields to detect if changes occurred.
I am pretty sure back in the days of ASP.NET 1.0/1.1, controls created during runtime needs to be added before Page_Load event of the Page Lifecycle (i.e. inside Page_Init).
Here's one article by Microsoft on it (for .NET 1.0/1.1):
HOW TO: Dynamically Create Controls in ASP.NET:
Note When you create dynamic controls
on a Web Form, you must create the
controls and add them to the controls
collection in either the Page_Init
event handler or the Page_Load event
handler. Otherwise, the controls may
not behave as expected.
However, in a few posts here, it seems like the above is not the case anymore. Controls added within Page_Load seems to be working for everyone else. Some of the posts include:
creating dynamic control in asp.net
Viewstate - utter confusion.
I've tried it myself and indeed it worked though I've not done enough test to fish out any unexpected behavior.
So is Page_Load a safe stage to add dynamic controls? Or is it only for .NET 2.0 and above?
I have studied this with Reflector, and the Control class does indeed bring things up to speed when you add them dynamically, no matter when you add them. It does everything - loads viewstate/controlstate, calls postback events, calls event handlers, etc. I don't know if it was different in ASP.NET 1.x days, but in 2.0 and above this is the case.
As for the "dangers" - there are some gotchas that the inexperienced user might trip over, so it is recommended that you add them in Page_Init or before. (Note that the PreInit event only applies to the page itself, not the Master Page or subcontrols). Off the top of my head (I'm sure there might be a few more):
By default viewstate loads positionally. That is, it ignores control IDs and just takes control placement in the tree into account when loading viewstate. If your dynamic controls were present when the viewstate was serialized, but are not present when it is deserialized, the wrong viewstate item might get assigned to the wrong control, thus leading to exceptions. This can be changed by some settings, though I'm now too lazy to search for them.
Since the "bringing up to speed" happens when the dynamic control gets added to the page, the order of some events might be unexpected. For example, if you add a TextBox control to the page in the Page_PreRender event, the Changed event of the TextBox will happen there and then. If your event handler code depends on the event happening with the rest of them before PreRender, then you are screwed.
You can add controls at any time. However, they'll only work with viewstate if you add them before page loads.
In fact, if you check the .Net 2.0 version of the page lifecycle link you posted, you'll stilll find this quote under the PreInit event:
Use this event for the following: ... Create or re-create dynamic controls.
The Page_Load event handler is an acceptable place to add controls. If you re-read your note you will notice that they state that.
Note: When you create dynamic controls
on a Web Form, you must create the
controls and add them to the controls
collection in either the Page_Init
event handler or the Page_Load
event handler. Otherwise, the controls
may not behave as expected.
If the ASP.NET 2.0 article you linked to, under "Catch-up Events for Added Controls", they discuss how added controls are brought up to speed with the page.
I have next situation:
I load dynamic controls during on init, and I do correct initialization.
I add dynamic control before postback
I don't add anything later in load
control is loaded and diplayed correctly
I press postback and nothing happens
Why I really don't know.. I tried everything. So control IS properly initialised. __EVENTTARGET shows the same path as the UniqueId of linkbutton that is firing it. All controls in tree have viewstate=true. So, I really don't know what this is not working.
Any idea? I am desperate.. I don't know.. if anyone could suggest me, if not solution, then just things I should check would be very good.
Is this problem just for this page or do you have other pages on the same site with the same problem?
I am assuming that you have the same problem on all pages.
It could be relate do javascript not being allowed. You could try to add the site to local intranet security are, then refresh the page.
Dynamic controls have to be added back to the control tree on each postback for the events to fire.
Dynamically created controls are not part of their container's viewstate, so setting it to TRUE wouldn't have any effect on the situation and are not evaluated until after the on_init call completes anyways.
I would wrap the logic that is populating these dynamic controls in with a conditional check for a postback if(!IsPostBack)
{ //Insert logic here }
If your dynamic controls take input from the user, or need access to their view state, then you would need to move this call to the Page_Load method as this is the point in the page's lifecycle where viewstate is first evaluated.
Is there any kind of event out there that would allow for a preload post back event.
The reason I ask is I have a control that adds sibling controls to it on postback events, however, by the time it has loaded the post back its too late to add the new control to the control collection. Therefore, the controls are never updated correctly.
Thanks!
Try the Init event.
Override CreateChildControls (make sure to call base!). In your postback event handler, make sure you are storing somewhere the list of controls that should be created dynamically, so when CreateChildControls gets invoked very early in the lifecycle on the next go-round, it will recreate the controls built on the last postback.
Here is a quick hack. You can always, query the __EventTarget and or the value of the submit button in init and can load dynamically the control.
But doing so, may not be appropriate as your control hierarchy would change and could cause problems.
As above, dynamic controls have to be added during the page Init event, so that they can be properly handled within the page's Viewstate. You might want to turn the Viewstate off for the page as well, since it can fire errors at you if the controls change.
As has already been stated the proper place to add dynamic controls is in the Init event.
Here's an article with more information.
Dynamic Web Controls, Postbacks, and View State
To get a better understanding of the ASP .NET page life cycle see:
ASP.NET Page Life Cycle Overview
This page explains the event order (and what happens in each one) in a postback, it helped me more than once.
I've just found this link, that can also be of use to you