In my asp .net C# project I have a page defualt.aspx on which I have placed 2 components.
So in all I have:
1) default.aspx (main page, not doing much code in it)
2) wuc_Lookup.ascx (doing a lot here, grabbing data, setting session, etc)
3) wuc_PageMessages.ascx (has a couple of panels and labels for message output
)
The intent is to use 3) in any page in my application. 1) and 2) are already working. My issue is that the Page_Load sequence is:
1st default Loads
2nd wuc_pageMessage loads
3rd wuc_lookup loads
The problem with this is that The wuc_pageMessage is relevant only after wuc_lookup runs.
My intent was not to put code in Page_Load for the message wuc_pageMessage control because I wanted to be able to call a method to post the message during the component load of wuc_lookup. I do this because only after wuc_lookup do I set the session which I use for the message value.
I actually got values showing up if I put the code in wuc_lookup to manipulate the code-in-front server control (panels and labels) using this.parent.findControl syntax...
But then when I try to rip that code and put it into the code-behind for wuc_pageMessage, and then call the method from the wuc_lookup it has fallen out of scope or context...
So I tried to change this.Parent by passing httpContext.current.handler as casting it as page...that didn't work...then I tried passing Object sender from the calling component...that didn't work either. Neither of them had the Parent property and or it was null which led me to believe that once the wuc_PageMessages.ascx loaded it was a dead deal until a repost happens and that is ugly and something I don't want to do.
I am having some implementation issues and I am not sure what to do. I have been stunk on this for eight hours and Is there just something I am not seeing?
I want to keep away from spagetti code. I don't want to have to scatter code-behind in 3 different files. Theoretically I should only need 2 of these to talk to eachother. i don't want code-behind in default..it's basically just a container. I want to trigger the wuc_pageMessage from wuc_Lookup.ascx without having it be "in" wuc_Lookup.ascx (peer web user controls) I want that to always be a peer relationship. Any advice would be great ...thanks...
Try moving the wuc_PageMessages logic from the page_load to the page_prerender event.
If you are going to use the preRender you would do it on the default.aspx preRender because this event fires after the wuc_lookup. Prerender will not fire on the components for some reason. So yes, this only solves part of the issue. I am not sure how you would get the alreeady loaded component of wuc_PageMessages to get back into scope. If you try to reference components on a component that has already loaded, you will get a null, like they are not there or not in scope anymore... anyone have any ideas?
Related
I have a single-page site that has an UpdatePanel. Within that UpdatePanel, there are UserControls that are dynamically loaded.
All linking between 'pages' (which are just UserControls) is done by using a WebMethod that changes a Session variable that stores the UserControl to load. The page reloads, with a new UserControl, and everything works great!
The downside to this methodology, however, is that I'm aware that Session variables don't scale well. Too many of them kicking around is not a good thing, so I've heard. I've unsuccessfully attempted to use different methods but not have been able to succeed. I'm looking to set the UserControl to load very early in the Page Lifecycle.
I've tried HttpContext.Current.Items, UserControl public properties and even UserControl HTML injection. It's just a big mess.
Is there a best practice for this type of scenario? Any helpful links or suggestions?
All is much appreciated.
Clarity update
I'm looking to change the UserControl to be loaded by the C# code-behind file through either jQuery method calls or a Webmethod. Session variables work, but don't scale.
I would use localStorage, you can store lots of information like this
localStorage.setItem('var', 'data');
and get the data back like this
var data = localStorage.getItem('var');
I understand that this will causes a page reload (partial or full, depending on how your UpdatePanels are set up)
But,
where in the code I should put it (client or server side)?
which control should I send to the method? Is it must be inside the UpdatePanel?
does this method work only for controls inside update panels?
must the control have a postback capability?
what is the engine behind this? How does this method work, so I could use it properly.
Thanks.
The function call returns a string of executable JavaScript, which you need to write to the client somewhere in your response.
Typically, you're sending your Page (this/Me) unless you have a control that you specifically want to handle the postback (ie, that implements IPostBackEventHandler)
GetPostBackEventReference is not related to UpdatePanels; if you have one, it will handle the postback.
No (see #2)
This makes a postback to the page. If you want it to raise an event when it posts back, you need to implement IPostBackEventHandler, either on your page or on one of your controls.
http://msdn.microsoft.com/en-us/library/ms153112.aspx
I have two user controls that sit on a page which determines which should be displayed. The user controls generate some html that is passed into an asp:literal and subsequently manipulated via javascript. It is done this way due to the lack of a suitable control that I am allowed to use on the project.
When a user clicks a view change button, a WebMethod is called on the main page (the one that holds the controls) from the control's javascript. From here, a static method on the control is called. The control then needs to regenerate the html and place it into the asp:literal for the view change to be complete.
My problem is that I am in a static method on the control's page, and have no access to the non-static genorateHtml function. I have tried a singleton pattern with no success (this could have been due to improper implementation). Any ideas on how to make this call? THANKS!
I used to hit similar issues at with one of the projects i worked on. The solution we ended up adopting was implementation of System.Web.UI.ICallbackEventHandler with partial rendering to return just the needed content depending on arguments. ICallbackEventHandler runs in the page lifecycle.
The only trouble we had then was performance issues relative to implementation which posts back the whole form instead of just the arguments you want.
Maybe the best way for you would be through this method in which they render the control from a static method. That would probably suit your needs.
Hope this helps!
I'm presently in the process of reworking a MultiViewControl based wizard process for our web application. I am having an rough time trying to make sense of the order that events are happening (Page_Load, Init, prerender, etc). Does anyone out there on the interwebs have details on dealing with one of these controls? Please don't just say 'google' it. I've done that and have yet to find a good, comprehensive site yet.
Admittedly, I haven't really elaborated on the problems I'm having with this control, so I'll try to do that:
Primary problem is the initialization of UserControls that live in different Views. In the existing codebase, the programmer was using a combination of multiviewcontrol.ActiveViewIndex = WHATEVER and Response.Redirect("PageWithMultiView.aspx?nextstep") and it made it all very convoluted. My task is to attempt to remove the Response.Redirect calls and use only the setting of the ActiveViewIndex. Is this even possible? Also, there are some cases where I need to initialize a control in a particular view only on the initial load and not on subsequent postbacks. I can use something like the IsPostBack flag but this is only ever set to false on the initial load. Subsequent reloads IsPostBack == true. I basically want to have IsPostBack set to false for the initial load of each View. Can this be done without doing a Response.Redirect to itself?
Hopefully this will make some sense to someone out there.
Thanks.
Greg.
I am having an rough time trying to
make sense of the order that events
are happening (Page_Load, Init,
prerender, etc).
Here you have all details about ASP.NET page lifecycle and events: http://msdn.microsoft.com/en-us/library/ms178472.aspx .
In terms of MultiView - you should NEVER use Response.Redirect when you work with MultiView.
If user can not switch to previous view then you can check previous ActiveViewIndex value before setting it to the new value, e.g.
if (mv.ActiveViewIndex != newIndex)
{
// this view is displayed for the first time
}
If user can switch to the previous views, I suggest to place an information about already used views in session or by placing hidden field on the form with ids of the views that have already been displayed and to use that information instead of IsPostBack.
I'm trying to edit a textbox's text in a Page_Load form on an ASP.NET page, but when I try to edit TextBox1.Text it throws a NullReferenceException because the TextBox has not yet been instantiated. Specifically what I'm trying to implement is this: http://www.codeproject.com/KB/user-controls/popupcalendarcontrol.aspx but it is written for an older version of ASP.NET and does not work for me. Is there a way to instantiate the controls at the start of Page_Load? or another event that I can catch on load? With a normal windows form I would call InitializeComponent() in the constructor.
There are absolutely different events you can attach to but it sounds like the page isn't loading the controls properly because they should be available by that point. You can take a look at the ASP.NET Page Life Cycle for more information.
Does the TextBox sit within a bound control, such as a FormView, GridView, DataList, etc? If so, then the control won't exist until after the databinding happens. Once that event happens, you can do something like
DirectCast(myDataList.SelectedRow.FindControl("myTextBox"),
TextBox).Text
I know that I am a bit behind in getting to this question BUT I have found something unusual that I can NOT find documented anywhere. It would appear that IF your page is "under" a Master Page, and IF you refer to ANYTHING on said master page, the controls to your current page are null - EVERYONE of them. I found this out by referencing "Master.Environment" - a public string - during my InitializeCulture method and having the FIRST control on my current (Default.aspx) page be null during Page_Load() - WHATEVER the first control was.
I know I am late but if this can help ANYBODY, I want the word out.