I am sure this has been asked before, but all of the links I find have to do with posting data to a popup page.
In my case I am trying to return two values/variables from the popup page back to the orginal page.
My effort thus far was to create two session variables in the popup page code behind, and then refresh the first page when the popup was closed. I'm not sure how best to do this. I do not want a fullpage refresh, I just want two textboxes to show the values of each of the session variables.
If I use the postback URL on my close button, my codebehind never fires to populate my session variables and it opens another instance of my calling page.
If someone has a link or tutorial to show this I would be very greatful.
Thank you,
Firstly I don't understand that returning value to the parent does need a session variable ?
Well you can pass the values to the parent in either json or XML or array, all you need is a piece of JavaScript which is window.parent and you can call the JavaScript method on the parent.
If your requirement is to save it in server session you can do whatever you are doing currently
I found these links which answered my question allowing me to solve this problem with ASP/VB not JavaScript, JSON or XML.
http://asp-net.wonderhowto.com/how-to/implement-cross-page-postback-asp-net-214606/
http://www.asp.net/web-forms/videos/how-do-i/how-do-i-implement-a-cross-page-postback-in-aspnet
Related
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.
I have a webpage with a textbox and a button and when the button is clicked i get som calculations on the value entered, but i cannot enter another value and see calulations on that new number.
How can I achieve this? Thanks in advance.
From your question it sounds like you want to be able to change the values without having to click the button again, and have the calculations redone. The reason clicking your button works is because the page goes through a Postback The calculations are then processed server side and returned after the page has loaded. What you want to do can be accomplished in a handful of ways including: jQuery or ajax. One thing you may want to look at is jQuery .post This can help you post the values of your form to a processing page and then set the return value on your form. On the other hand since you're using .NET you could also take a look at the Microsoft AJAX Control Toolkit One place you could start is by looking at the Update Panel. Good luck and I hope this helps!
I have two controls of interest on a page: a DropDownList and a Button. If the user presses the button, he gets a popup form which, when completed, causes the base page to completely reload, losing the value in the DropDownList. To clarify, it's a refresh, not a postback. I cannot change it to make it a postback. What is the most straightforward way of persisting the selected value in the DropDownList across this page refresh? I cannot avoid the page refresh, because the data entered in the popup is reflected elsewhere on the base page.
Update
I've cobbled together a tenative solution that I'm not terribly happy with: when the user clicks the button, I use javascript to get the current value of the dropdown and pass that with the querystring to the popup being loaded. When the user clicks "Save" on the popup, which causes the data to be saved then the base page to be reloaded, I first store the querystring value into a Session variable. The base page, on loading, looks at said Session variable. If a value is present, it sets the value of the dropdown accordingly and deletes the Session variable.
Although somewhat kludgy, it's the best I can come up with. I know that my Gracious Benefactors dislike using Session variables, but given the page reload, I cannot come up with an alternative. Also, since the Session variable is short-lived, being created shortly before a page is closed then being deleted shortly after the succeeding page is opened, I'm hoping this will be acceptable.
Contrasting opinions, refutating my solution or reasoning, are enthusiastically welcome.
Conclusion
Ultimately, after I described the solution to my Gracious Benefactors, we agreed upon an alternate approach: if a selection is made in the DropDownList, it must be saved before opening the popup. This avoids the whole ViewState problem altogether.
For updated question:
The solution you are trying sounds like it should work. It's not the sort of thing you want to use SessionState for but there are requirements here that make the situation out of the ordinary.
Depending on how you are getting the base page to reload you may be able to add a query string to that which would save you from putting hte value in the SessionState. But I imagine you have probably considered that.
But basically, as Postback values and viewstate are out of the question, SessionState and query strings are you only real option. Oh, unless you are allowed to use HTML5 local storage? (probably not)
From before question update:
If the aspnetForm is being posted back the the value should be persisted automatically by means of the postback values. So the first thing to know is whther your form is going through a postback or if you are refreshing the page in some other way.
If you can't postback the main form then as rockinthesixstring said an Ajax post might be what you need.
Also, if you are doing anything fancy with binding the datasource to the DropDownList or trying to persist the selectedValue yourself then check and re-think that.
Pls somebody help me with viewsate. Suppose i have created two forms. First form contains First name and Last name and one button called NEXT. And Second form contain two fields and two button like Back and Save. While i am entering some value in form1 pressing one NEXT button and redirecting to second page. There when i am pressing Back button from second page it should come to first page whichever data i filled should exists, but in my case its not showing only empty form i can see when i am pressing on back button.
For this i have used viewstate mechanism. in page directory i have set enableviewstate=true.
postbackurl in both the button. Pls somebody help me what is wrong with me.
Thanks,
Sumit
Viewstate won't carry information from one WebForm to another. It only carries information across postbacks on the same WebForm.
You want to use another method, like SessionState, to carry information from the first page to the second page. Otherwise, you could combine all your inputs on the same page and separate them into multiple steps using something like the ASP.NET Wizard control.
David Lively's suggestions of cookie or database solutions are good, too.
ViewState will help you ship data between views/postbacks of the same page, but isn't really going to help you when moving data between separate pages.
In your first page, populate a cookie or database with your form fields. Any form can then update the cookie, delete it, or what have you.
You can call a javascript function that is doing a "real" back. Maybe I am missing something but this is what I would do.
onClick="history.go(-1)"
When a page is called from some other page it is not a post back, it is viewed as if it is a first time call... When a page is called from the same page then it is termed as a post back... View state or in the sense control values are maintained only during post back, and gets reseted to form values during first time call...
This is the reason behind why you are not seeing the values of the controls.
As others suggested, try using session or cookies and the best option would be Wizard.
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.