I dynamically load a User Control, with an Update Panel inside a Place Holder.
When I click a button from the User Control, should refresh the Update Panel contents, but it refresh the entire page instead, and the User Control is disappearing from the page, because the page's Page_Load does not load anything if it's a PostBack.
How I can fix it?
Whenever a partial or full postback happen , Automatically all update() method of all updatepanels fire . For preventing such this behavior you need to set UpdateMode="Conditional" property . In this situation you need to specify asynchronous trigger Or ChildrenAsTriggers=true .
for preventing a dynamically loaded-usercontrol to be disappear ,It's good to save it in ViewState , Here is a tutorial and sample application
I think you'll need to reinject the control in page_load or pre_render. Dynamically created controls don't live through postback.
Make sure you are creating the control EVERY page request, regardless of GET/POST. Also, make sure you are giving it the same ID.
I like to override the CreateChildControls method.
You need to add the control page to the page in the page_init method. It has to be added on each post back. The control will retain all the values even after adding it back.
There is a full working example at this link.
Related
I have a ASP.Net(C#) page. When a user selects a value in dropdownlist, some new controls will be visible to him.
I am able to that now, but the page has to reload every time and state has to be maintained between postbacks.
Is there any way to do the same without reloading of the page in a easiest way possible without using ajax control toolkit?
Additional info: the data for the dropdownlist is coming from the database, and some places it has to be all server side so i can't use javascript .
You can try this idea: http://msdn.microsoft.com/en-us/library/ms178208(v=vs.100).aspx. I have not try it before but it seems logical.
you should go through updatepanel. Put all the controls inside a updatepanel which you want to show on selectedindexchanged event of the dropdownlist and write code behind on selectedindexchanged event of the dropdownlist accordingly. Hope this will help you...
When the ASP.net Page is Postback the controls inside the table is disappear,
but when i click on button that has that code which cause transfer to the page:
Server.Transfer("~/Admins/EditUsers.aspx");
all controls appear easy with no problems.
Then,is there is need to make refresh to the page, or what can i do?
Thanks
A postback already performs a page refresh automatically.
If controls are disappearing, that suggests that you might not be creating them on the postback. Note that tables do not store their contents in ViewState. Is there any chance you are testing for IsPostBack in your page Load handler? If so, you must recreate the table on every load, whether a postback or not.
Beyond that, you'd probably need to provide a bit more specific information.
I have an update panel that contains a repeater that calls a user control into each row. When I click a button inside the user control, the page does not refresh at all, only when I reload it completely. How can I make the update panel refresh from user control's button click?
Phairoh is correct that your button needs to successfully cause a PostBack.
There are three things that affect when a UpdatePanel is updated:
The UpdateMode property - This takes two possible values, Always and Conditional.
If it is set to Always then any postback o the page will cause the UpdatePanel to update.
If it is set to Conditional then the UpdatePanel is only updated when the UpdatePanel's Update method is called or when one of the UpdatePanel's triggers does a postback.
The Triggers proroperty - Defines which controls will cause the UpdatePanel to be updated when UpdateMode is set to Conditional.
The ChildrenAsTriggers property - This is a boolean value that determines if child controls of the UpdatePanel are automatically considered triggers without having to be added to the Triggers collection.
Because your button is in a UserControl it won't be easy to add the control to the Triggers collection or to have the button call the Update method on the UpdatePanel that is not inside the UserControl.
Because your UpdatePanel contains the UserControl's your best bet is to enable ChildrenAsTriggers. If this doesn't work try setting the UpdateMode property to Always. If this still doesn't work then Phairoh is probably correct and your Button isn't posting back.
Sometimes solving this problem not really convenient with Triggers. So here is another fancy approach which could be used even from your user controls without any knowledge about Update Panel:
var scriptManager = ScriptManager.GetCurrent(Page);
if (scriptManager != null)
scriptManager.RegisterPostBackControl(SomeControlID);
Are you sure your buttons on your user control are attempting to do a postback? I haven't used update panels in a while (and I'd actually recommend avoiding them) but if I recall correctly they will refresh whenever a postback is done within them. This means that your buttons must be Asp:Buttons (or similar controls that cause postback) and not have some kind of javascript on them that would not allow their action to continue (such as a return false).
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