I'm trying to describe it in as few steps as possible:
I have Page1.aspx with lot of controls, and Preview and Save button among those. I also have Page2.aspx that is the redirection target of a Preview Button click.
Since I need all the controls selections from Page1 to draw a preview on Page2 the redirection is done with setting Preview's PostBackUrl.
I also must have preview shown on a new tab or window so I used onClientClick="aspnetForm.target='_blank'" for Preview button definition.
Save button-click callback, after storing data to a database does redirection to some Page0.aspx (initial list of reports - the subject of the code)
Preview button works fine - a preview renders in a new tab, but when I go to the old tab and click on Save, I see from debugger, that firstly Page2.aspx(?) and secondly Page1.aspx are loaded. Then all the data is stored in the db, but though Page0 redirection is executed Page1.aspx stays loaded in the browser.
I have no idea what processes are behind this. Could one who knows give me an insight? Or if you consider my approach impossible to implement give some idea how to do the same?
If it's of importance, everything on the Page1 is located in an update panel.
Thank you very much for replying
In ASP.NET there are basically zero (0) circumstances in which you will ever send form data from one page to another. Although what exactly you are trying to accomplish is vague, you can consider some of the following:
Isolate unique operations/systems to a single page. If you have something like a User Profile, don't have three different aspx pages; just use a single page for the user or admin to manage that data / functions. Postback events are your friend.
Understand the difference between ViewState and traditional form data. I'm guessing that if you're trying to post form data from one page to another, you probably don't understand the point of ViewState. Using a single page to maintain temporary data that the user is currently working with is a great use for ViewState. If you want the data to appear on another page then you need to consider the data from the previous page as final and thus should be saved to a database or some other medium.
These are just some general guidelines because there is no exact answer to your problem without saying something generic like "You're doing it wrong." I would recommend starting by never again trying to post form data from one aspx page to another.
Related
I can't believe how many articles I have read and example code I've tried to understand, with no success in accomplishing what I need to do. Hopefully someone can help me out by providing some example code or pointing me to another resource.
I am working in ASP.NET 4.0, C# using VS 2012 Express. The project is a web site. I have a UI page that contains checkbox controls and dropdowns for a user to set preferences. At the bottom of the page is a checkbox for the user to agree to some terms and conditions and an image button they click to get the results based on their preferences. This all works and so does the results page.
The problem is that the results page takes as much as 90 seconds to complete. I can't just leave the user with a "Loading..." on the status bar of their browser. So what I am wanting is:
User clicks to get results
Results page loads immediately
Once results page has loaded, a call is made to server that begins the 90 second process.
User is provided a status display of the progress.
Once process completes, a link is presented for them to view their results.
I see many examples with varied approaches. Most of them require the user to click a button to begin the process. I don't want the user to have to click another button - I just want the process to begin when the results page is finished loading.
Additionally, I'm looking for an idea of how to code the client page to make calls to the server to obtain the status of the process. Preferably a percentage value and a text message for each step of the process. Ie:
25%
Compressing files...
I've seen some Web Method examples, but I don't think I've seen a single one that demonstrates beginning the process initially without having to click a button to invoke it initially. I considered putting the Javascript call in the , but it is contained in a Master.Master that is used by many other pages.
Does anyone know of any code examples that might help me accomplish this sort of thing?
I found a really nice solution from EssentialObjects.com. Their progress bar control is free, although I needed their CallBack custom control to do what I wanted - the CallBack control is not free.
Hope this helps someone else out!
We have a site where all pages are output cached, i.e. the caching is on aspx-level with VaryByParam="*". Now there is a requirement to make a gallup control, i.e. a small "How is this site working for you?" and then when the user clicks an answer the results are shown.
The gallup is implemented as a usercontrol that is added to the master page so gallups can be added to any page to which a gallup is created in the cms. The problem is that output cache naturally caches all clicks so when user no 2 votes he sees the results that where calculated after the first vote on that alternative.
Now I'm trying to use cache substition. I added an asp:Substition tag where the user control used to be, load the control dynamically and render it (using this approach http://coderwall.com/p/4ajzqq). The problem is that the postbacks that voting triggers is never fired. Apparently the method that the substition control executes is loaded outside the page life cycle or too late.
Any ideas?
Regards,
Mathias
I solved this by skipping the substitution control and just used the user control as normal, so the gallup/question view was output cached. Then in the click handler for the answer alternatives I added
Response.Cache.SetNoServerCaching();
which exempted the results view from output cache and hence it was updated as it should.
It is also possible to use Response.Cache.SetNoServerCaching() in Global.asax, using VaryByCustom. It merely requires sensing in Global.asax whether the page is a post-back or not. Here is a code example.
I have an asp.net application with a search page, with criteria and result display on the same page. I want to keep a copy of the populated search page to redistribute it later to the same user, upon the button click on another page. It's kind of a "return to search" button. How can I do that?
Here is some context:
The search criteria is made up of some basic controls, and the results are then (after postback) displayed in a GridView. I also have a master page. Simple as that.
Now consider the following scenario: The user can investigate the results by clicking links that show detail pages, and can drill down over quite many detail pages with associated data. If he/she wants to get back to the search results he/she needs to click the back button of the browser quite many times.
I would like to provide a "Back to search" button on the master page that allows to return to the populated search page with one click.
Note:
I can not use the browser history in any way because it must work also when the user opened one of the detail views in another tab.
I have seen Keeping the Viewstate persistent and retrieve it on demand but it hope there is an easier solution because my grid is paginated and I have also more than one search page, where I would like to return to just the last one used.
Thanks, Marcel
I can offer some logical ways to resolve this problem, without using specialized asp.net features if they exist:
1) Is there some way to save the search string in GET request? So you can save it some way between moving through pages?
2) Another way is caching search pattern (with all filters or what you need there) somewhere - in database, for example and contain some key in get request, which would point on this pattern.
I'm doing some brainstorming for a portal framework, and I'm envisioning a breadcrumb navigation stack that is tracked via the ViewState (so that if the user clicks "back" in their browser and clicks some other link, the breadcrumb trail will depart from the right page). My pages are really just ascx controls that get loaded into a placeholder control on the main portal page based on the URL. When the user clicks a portal link, there is a postback that loads the original page and invokes the given link's "clicked" handler, which should then "push" the current location onto the breadcrumb stack before sending the browser a redirect instruction to change the URL to that of the page that I want to go to.
That's as far as my brainstorming goes for the moment, because once we perform a redirect, we lose the ViewState. Rather than doing the redirect, I've thought of simply telling my main portal page to replace the current page control with the target page control, thus avoiding the extra http round-trip and allowing me to keep the ViewState. But then my entire website experience occurs in the context of a single URL, so I lose URL bookmarking among other things. And if I wrap some of my controls in AJAX panels, the entire site happens in one page request as far as the browser's history is concerned.
What I would like is some way to have the browsing history and URLs behave as if each link is leading them to a new page with a descriptive URL and all that, but still have some way to know the path that the user took to get to the page that they're on (ViewState seeming to be the simplest way to track this).
Could anyone suggest some techniques I might try using?
First suggestion... You may want to look into ASP.NET MVC. However, I have to admit to some ignorance here as I'm not sure that would really solve your problem. But it sounds like the sort of thing MVC would be suited for.
Second... it's possible to override the methods responsible for saving and loading ViewState. One of the things you can do, for instance, is push the ViewState into the Session rather than sending it down to the user and back up on postback. You could easily add some custom code here.
Third... I think you may want to rethink part of your design. The ViewState really serves one purpose: It recreates the state of the page as it existed when the page was rendered for the user. If you are moving to a different page, or a new set of controls, why would you need the ViewState at all? The ViewState itself is really just a hack to begin with... ASP.NET's way of maintaining state on top of a stateless system. (but that's a whole 'nother discussion) We have other methods of maintaining state... the primary mechanism being the Session object. Why not save your breaacrumb data there instead?
I would look at using cookies. For performance reasons, you really want to avoid HTTP redirects if you can, and ViewState only works if the user submits a form, not for regular links.
You might do something like maintain several path lists in cookies that show the path that the user took to go from one page to another. Maybe you set a unique ID with each page that is applied by some JavaScript as a query string when the user clicks on a link, and the server uses that ID and the past history from the cookies to determine how to render the bread crumb on the next page?
I'm writing an asp.net web app. and i've hit a bit of a brick wall.
basically i have 2 pages, the main page with a text box in and a popup that contains a treeview.
My problem is this. when i select a treeview item i want the program to perform some database transactions using asp.net and then pass the value retrieved from the database into a javascript function that passes the data back from the popup page to the parent page. My problem is that i cannot find any way of calling a javascript function from asp.net. I've tried assigning attributes to controls on page load, but this does not work as when the page loads the data has not been retrieved from the database.
Have a look at the ClientScriptManager class. You can register scripts from code-behind that will run when the HTML page loads. Those scripts can call other javascript functions on the page.
There are many tutorials and examples on the Web. Here's one I found that may help but there are many more.
How to use the client script manager
You hit the nail on the head when you said "I've tried assigning attributes to controls on page load, but this does not work as when the page loads the data has not been retrieved from the database." You just need to discover when you're pulling the data from the database, and then assign the values after that. Without looking at your code, there's no way to know for sure, but Page_PreRender is probably a good bet to assign your values...it's probably after you're pulling information from the db...it's pretty much the last place that you can make things happen before the html is generated for the client.
You can invoke a function resided in the Main Page and call that function in the Main Page from the Child Page which is your pop up window.
Please refer to these links for references
http://chiragrdarji.wordpress.com/2007/03/10/call-parent-windows-javascript-function-from-child-window-or-passing-data-from-child-window-to-parent-window-in-javascript/
http://www.webmasterworld.com/forum91/2957.htm
http://hspinfo.wordpress.com/2008/01/12/call-parent-windows-javascript-function-from-child-window/
This one helps with retrieving popups from values using javascript
http://www.eggheadcafe.com/articles/20060117.asp
This one shows how to fire a postback using javascript, and manage it in the codebehind.
http://weblogs.asp.net/mnolton/archive/2003/06/04/8260.aspx
If you put them together, and use Control.ClientID to find the actual "html name" of your asp.net controls, you'll be able to set that up in no time.
Might not be the prettiest way to do it in town, and incidentally make little baby Jesus cry, but anyway, it works.
[edit]Oh. I just saw that it seems I answered the question the other way around, or "how to trigger codebehind from Javascript". I think the method I suggest may help you, if you use it right.
The javascript of the popup should pass the information to the parent window, and the parent window function should call a postback when it receives the information.
The javascript of the popup window should be only registered on a postback with the correct information retrieved, so that when the postback occurs on the popup because of the selection of the right information, the window closes and passes the information to the parent page.
The parent page, triggering postback, does the thingies you need it to, and the app resumes "normally" from there on, doing whatever you need it to, outside of the popup page.