Does anyone have an example of this? I want to create a TextBox inherited control that creates a CustomValidator within it. I don't believe I can create the CustomValidator as a child of the TextBox. I think it needs to be added as a child of the Page itself (I could be wrong).
Any help??
Thanks!
Ok I figured it out. The validator event wasn't being added to the Page.Validators at the right time. I was creating the validator in the CreateChildControls method. This is wrong. It (they) need to be created in the control's Init method so that they are added to the validator stack during the correct time of the page's life cycle. It was simply a move to this Init method and all works fine now.
Related
Given: I have a custom server control in the markup of an aspx page. This control creates child controls in its CreateChildControls() method (e.g. it retrieves content from a database and based on that content dynamically creates either a CheckBoxList or a RadioButtonList)
Now I understand that I cannot access the dynamically created controls on postback unless I add them again on Page_Init or Page_PreInit (as per here).
My question is, how do I add them again explicitly in Page_Init or Page_PreInit if they are just going to be added yet again when we get around to calling Render() on each of the custom server controls?
I'm very certain this is not a unique problem, so there must be a best practice way of doing it...I just don't know what it is :/
All you need to do is create you Custom server control in the Pre_Init. Everything else is handled for you. I think you're thinking too hard about what is going on and it's confusing :)
The custom control will render the child controls while in the Pre_Init event. They won't get rendered twice.
I seem to have a bit of a bug, I have a ASP.NET repeater control with a link buttons in it and the link button has the have the causes validation property set to false.
However; when clicking it which makes a panel visible on the web page, the asp.net required field validator controls trigger and shows their error messages. On those controls that I have the validator controls on.
Any ideas as to what might cause it to be ignoring the causes validation property set to false?
On my opinion, you should set different ValidationGroup properties values for repeater control and for control that is the source for required field validator. It is possible that container for repeat control has raised event that can be heared by required field validator.
If mentioned above cannot help then try to disable client validation for RequiredFieldValidator using EnableClientScript="False" for it. And activate RequiredFieldValidator when it really usefull. For example in the some button event handler you can apply such code:
MyButton.Validate();
if (MyButton.IsValid)
{
Do what you want...
}
For anybody that has this problem and stumbles across this post, here's what I found.
Turns out the problem was happening because I had EnableViewState="false" set on the Repeater. This was breaking the event postback somehow, and making every validator on the page fire. All I had to do was manually call DataBind() on the Repeater from within Page_Load(), and it cleared right up.
try to set the visablity of the panel true all the time in design view,, and check the validation again.
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
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.