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Clear POST data after submission so user can't click Back in browser

My form when redirected to the thank you page after completion seems to retain all the data in the values field so if the user clicks back everything is there meaning they can just resubmit it and its super annoying.
if (emailSent) {
Response.BufferOutput = true;
Response.Redirect("MYDOMAIN/redirect.aspx");
};
Above is where I redirect after the form has been submitted. For my code to pull the data I am using:
Request.Form[randomFormField]
When I redirect and then click back everything is there.
$(".submitBut").click(function() {
$(this).closest('form').find("input[type=text], textarea").val("");
window.location.href('MYREDIRECTDMAIN/redirect.aspx');
});
Above is another one of my attempts
I have tried a variety of different things and nothing seems to work. I need an ASP.NET solution or C# or JQuery.

Javascript on page load: clear all form fields
Uhm....
$(document).ready(function() {
$(':input').val('');
});
References:
Input
Clearing

MVC 4 with jQuery Mobile page seems to be caching and controller method not being called

EDIT
Figured it out.. $.ajaxSetup({ cache: false }); wasn't working because i had data-ajax set to turned off on the form and therefore i wasn't able to set no cache ajax on it.. just for completeness if anybody knows how to get this done WHILE dada-ajax is set to false then please post so here
Something else that I just tried and it worked was to simply add data-ajax="false" to any link that you want a page refresh on. Meaning that if I have data-ajax="false" on a link it will always refresh the page before showing it!
For example the link I had a problem with was
Add a new weekly update
and the problem was that for some reason that page was caching and always showing the cached page.. So one of the easy fixes was to add data-ajax="false" to it and that forced a reload of the page everytime
Add a new weekly update
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Question:
I have a options menu which brings up a form which also has a cancel and submit button.
Once the form is submitted there is certain validation that runs and if something is missing it returns to the form with some validation text.
Now if I click the cancel button at anytime i should be brought back to the options menu and if I click on the same button that brings up the form i should see a brand new clean form and this works fine if I do it before the validation.
The problem is that if I submit a non valid form which returns with the error validation messages and THEN press cancel it seems that the page becomes cached or something similar because from that point on anytime I click on the form options menu button the same form shows up each with the validation errors and data. I put a break point in the method that returns the form View() and they are never hit so for some reason it skips the entire method which creates a new form and somehow just shows the old page.
The cancel button is the following
Cancel
Does anybody know what is happening? is it being cached somehow when it returns to the same page with the validation errors??
** EDIT **
I Tried adding [OutputCache(NoStore = true, Duration = 0, VaryByParam = "*")] in front of the controller by to no avail..
I also now added
$.ajaxSetup({ cache: false });
to the top of my $(document).ready(function () but that also does not seem to be doing anything, do I just put it there or do I have to call it somehow?
I checked System.Web.HttpContext.Current.Cache and the page doesn't show up there.

Have you tried setting the output cache options on the controller action like
[OutputCache(Duration=600,VaryByParam="id")]
You might also want to try making sure jquery is not caching the request as well. You can globally turn off jquery ajax caching using the information here: How to set cache: false in jQuery.get call

You can try using $.mobile.changePage() to transition to the page, it allows you to set some options, one of which is reloadPage.
reloadPage (boolean, default: false) Forces a reload of a page, even if it is already in the DOM of the page container. Used only when
the 'to' argument of changePage() is a URL.
Source: http://jquerymobile.com/demos/1.1.1/docs/api/methods.html
You could work this into your link with something like:
<script>
function changeMyPage(url) {
$.mobile.changePage(url, { reloadPage : true });
}
</script>
Cancel
jquery Mobile pulls multiple pseudo-pages into the DOM at one time and normally deletes (.removes()) a pseudo-page after you've navigated away from it. It however sounds like that's not happening so you may need to use my above code (or something similar) to force a refresh of the page.

You need to clear your ModelState before hand.
This should work:
if (ModelState.IsValid)
{
//saving
if (result > 0)
{
**ModelState.Clear();**
return View(new CategoryViewModel());
}
}
How to Clear model after submit the data in database in MVC3

IsPostBack property of the page never gets false even after page refresh

I get stuck in a very unusual problem. I've a code written in C# which is simply checking IsPostBack property on the Page_Load. I know that IsPostBack remains false when page lands for the first time and bocme true only when any control post the form to the server (having runat=sever).
I also know that if we hit refresh, the IsPostBack property should change to false (since refresh is not a postback).
This is the sample code:
if (!IsPostBack)
{
// If I click on any control on the page, and then hit refresh,
// the code inside this block should execute, but this is not happening.
// After first postback, I tried refreshing the page for more than
// ten times, but always finds IsPostBack=true
// ...
}
else
{
// ...
}
I clicked on a server side button (a postback), then hit refresh. I assume it will go to the if block but no luck. No matter how many times i hit Refresh on browser, IsPostBack is always true. which is truly an unusual activity I've never seen before.
I would really appreciate any help. I need to know why this is happening, is this a browser related problem or something else? I used mozilla and chrome.
Every time I hit refresh, I get a warning on both browsers.
On chrome: Confirm form submission
The page that you're looking for used info that you entered, returning to that page might cause any action you took to be repeated.Do you want to continue?
On mozilla: Confirm
To display the page, firefox must send info that will repeat any action...
Thanks in advance for any kind help.
Praveen

Most browser will do a post of the same data if you refresh after posting.
This is the meaning of the dialogues you have seen (they are asking if you want to re-post - click yes/OK means a re-post).
In order to avoid the re-post, simply go to the address bar and press enter. That will cause a new request to be issues rather than a re-post.

Those dialogs that the browsers put up tell you that they are going to do a postback instead of just get'ting the page. And you can see in your code that the warnings are accurate - any handlers that were invoked on the original postback will get invoked a second time. This is one of the main problems with postbacks - they essentially break the refresh key. If you just want to load the page, you have to mouse up to the address bar and hit enter. This will load the page with IsPostback false.

asp.net: how do i prevent users from posting the same data multiple times

i have a little asp.net web application.
it is a front end to a sql-server-2008 database.
after they fill out all the data, they will press submit and the data will be sent to the database.
after this point if the user refreshes the page, the data is posted again!!! how do i disable this from happening?

Send a Location header back to the user that redirects the browser to another page: refresh will then reload that other page rather than resubmit the old form.

This is caused by the last request being a POST request to the page, what do you need to do is a redirect so the last request becomes a GET.
After you have handled the post data you can just do a redirect to the same page with:
Response.Redirect("~/ThePage.aspx");
This will prevent you from presenting a message to the user straight from the code behind, if you want to present a success message using this method you will need to add a querystring or something similar:
Response.Redirect("~/ThePage.aspx?result=success");
And then check on the page bind if the querystring to present a success message is set, such a check could look something like this:
if (Request.QueryString["result"] != null && Request.QueryString["result"].ToString().ToLower() == "success")
{
//Show success message
}
Another solution which probably is superior but might require some more work is to wrap the form in a updatepanel, you can read more about it here: http://ajax.net-tutorials.com/controls/updatepanel-control/
An updatepanel will make the form submit with AJAX instead of full postback.

You need to follow the Post/Redirect/Get pattern which is explained on WikiPedia and alluded to by Femi. In your code after you've done your processing do a Response.Redirect to the desired page.

See this article about the PRG pattern: http://en.wikipedia.org/wiki/Post/Redirect/Get
In short, after the user POSTs (submits) data to your server, you issue a Response.Redirect to have the users browser GET a page. This way, if the user presses the reload button, it is the GET request that is repeated.

Prevent duplicate postback in ASP.Net (C#)

Simple one here... is there a clean way of preventing a user from double-clicking a button in a web form and thus causing duplicate events to fire?
If I had a comment form for example and the user types in "this is my comment" and clicks submit, the comment is shown below... however if they double-click, triple-click or just go nuts on the keyboard they can cause multiple versions to be posted.
Client-side I could quite easily disable the button onclick - but I prefer server-side solutions to things like this :)
Is there a postback timeout per viewstate that can be set for example?
Thanks

I dont think that you should be loading the server for trivial tasks like these. You could try some thing jquery UI blocking solution like this one. Microsoft Ajax toolkit should also have some control which does the same. I had used it a long time ago, cant seem to recall the control name though.

With jQuery you can make use of the one event.
Another interesting read is this: Build Your ASP.NET Pages on a Richer Bedrock.

Set a session variable when the user enters the page like Session["FormXYZSubmitted"]=false.
When the form is submitted check that variable like
if((bool) Session["FormXYZSubmitted"] == false) {
// save to db
Session["FormXYZSubmitted"] = true;
}

Client side can be tricky if you are using Asp.Net validation.
If you have a master page, put this in the master page:
void IterateThroughControls(Control parent)
{
foreach (Control SelectedButton in parent.Controls)
{
if (SelectedButton is Button)
{
((Button)SelectedButton).Attributes.Add("onclick", " this.disabled = true; " + Page.ClientScript.GetPostBackEventReference(((Button)SelectedButton), null) + ";");
}
if (SelectedButton.Controls.Count > 0)
{
IterateThroughControls(SelectedButton);
}
}
}
Then add this to the master page Page_Load:
IterateThroughControls(this);

I have had the same scenario. The solution of one of my coworkers was to implement a kind of Timer in Javascript, to avoid considering the second click as a click.
Hope that helps,

Disable the button on click, utilize jquery or microsoft ajax toolkit.

Depending on how important this is to you, could create an array of one time GUID's which you remove from the array once the update has been processed (ie posted back in viewstate/hidden field)
If the guid is not in the array on postback, the request is invalid.
Substitute database table for array in a clustered environment.