I have a masterpage that has a dropdownlist.
The data in the page is reliant on the dropdownlist of the master.
However, when the dropdownlist is changed, it appears the page events fire before the dropdownlist changed event in the masterpage, so the data is not updated.
The only way I can see this is working, is making the events happen in page prerender.
Anyone have a better solution?
The only thing I was able to do to make this work was move my load events to prerender events (like I mentioned in my original post) based on the the life cycle. If anyone has a better idea, please post.
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 have a web page with a datagrid and a user control.
The user control has an event which the web page subscribes to.
On the user control event I need to rebind the datagrid on the web page.
I'm coming up with all sorts of problems due to extender controls that are attached to the grid indicating that they cannot be registered after prerender so it looks like the user control event occurs to late in the page life cycle. Either way those kinda errors would indicate that I'm on the wrong track completely.
I do not want a reference to my page in the user control if at all possible.
What is the best way to achieve this.
I had tried Binding the grid on PageLoad every time but found that although the Databind happened and the updated data was in the datasource that the grid contents did not reflect this. [Is it the GridView viewstate thats playing with this?]
Ding a full refresh or using a button to the page to rebind the grid allowed me to display the correct value.
Thanks in advance,
Liam
"I had tried Binding the grid on PageLoad every time but found that
although the Databind happened and the updated data was in the
datasource that the grid contents did not reflect this. [Is it the
GridView viewstate thats playing with this?]".
I think that the answer (in part at least) to this is that the third party control is using callbacks to get back to the server and not postbacks so this may be the issue. As I understand it the grid was binded OK but not rendered. [I hadn't come across the differences between Callbacks and Postbacks until this week!!]
I'm open to correction on this though. :)
Liam
I have a control which has an ImageButton which is tied to an OnClick event... Upon clicking this control, a postback is performed and the event handler is not called. AutoEventWireup is set to true, and I've double checked spelling etc.... We haven't touched this control in over a year and it has been working fine until a couple of weeks ago.
We have made changes to controls which load this control... so I'm wondering, what kind of changes could we have made to stop this event handler from being called? There is quite a bit of Javascript going on, so this could be the culprit too...
Edit: Some clarification... we are dynamically loading the parent control of the ImageButton in the OnLoad event of the page... if that makes sense.
AutoEventWireup is irrelevant. Is your ImageButton loaded dynamically, i.e. not written out in mark up? If it is loaded onto the page late in the Page lifecycle e.g. in PreRender then the event will not fire.
If there is a JavaScript issue your page will not even PostBack. Is that happening?
Did you give the ImageButton an ID?
I def agree with what BritishDeveloper said. I had a similar problem where I was dynamically loading controls, but I couldn't get a reference to the control using Page.FindControl("controlName") Someone pointed out that I needed to keep the page lifecycle in mind. I found out I needed to make sure to load the control in the PageInit because after doing an async postback the control was still there, but not loaded in the postback so there was no way to find it. This was all in csharp codebehind and ajax though, but I'm guessing the control isn't getting reloaded.
So, as it turns out we set the PostbackUrl property on one of our buttons in control A... this caused the event handlers for control B not to fire when a button in control B was pressed.
If you create a control dynamically. Any time you fire a postback using the new created control, you need to recreated it. Just think that your application are running at a server. How can the server hold information on controls created dynamically? Don't use Page.IsPostBack to create postback. PostbackUrl is bad solution. Workarround will be need.
I can go into a little more detail ... I just lost several hours fixing my own issue similar to the issue described here. In the course of creating some search controls, I added a pair of ImageButtons and set the PostbackUrl properties on them. A few days later while testing new code, I noticed that none of my other buttons on the webform were posting back properly. They would fire a postback, but the code-behind was behaving as if every postback was an initial page request and none of the event handlers were firing.
After several hours of troubleshooting, I came across this post. When I went back and removed the PostbackUrl from those two ImageButtons, everything went back to normal. I don't know why it was causing this issue, but the fix mentioned here worked for me. I want to add that my ImageButtons were not dynamically added ... they were in the markup and this issue still cropped up. Search your markup for any controls with PostbackUrl set ... remove that (program around it if needed) ... see if your event handlers will fire properly.
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
I have an asp.net web page with a ton of code that is handled in the Page-Load event of the page. I also have a dropdown box on the page that should reload the page with a new value, but I would like to get this new value before I process the entire Page-Load code.
I am trying to get my head around ASP.NET page lifecycle.
Should I move the Page-Load code to a later event or is there a way to get the value of the dropdown list value before the the Page-Load event begins?
TIA
I would use Page_PreLoad instead of Page_Init, because it is raised after all postback data is processed.
Try Page_Init
As noted before, Page_Init is what you want. But I emplore you to make your pages as loosly coupled as posible. Look into the MVP pattern for starters. Also, make sure that most of your logic is in your domain objects.
There shouldn't be too much code in the Page_Load event. If there is, it shoud be broken up into concise methods so that you don't have crazy code.