Prevent form resubmission and insert into database on page refresh
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8 سال پیش
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Prevent form resubmission and insert
Prevent form resubmission and insert into database on page refresh
here in this tutorial we have explained how to prevent form resumission on refreshing the page. all you just have to do is use response.sendRedirect() instead of request dispacher
Clicking the "submit" button on a form sends a request to the web server, which includes all the data entered on the form. Not only the URL but also the form data is part of the request, and this request is remembered by the browser. If the user clicks "refresh", the browser repeats the request, sending the same URL and form data to the web server again.
But forms can be submitted in two different ways, GET or POST, depending on the "method" attribute of the "form" tag. There is a convention that a GET request has no side-effects; it only fetches data but does not make any changes to the database. On the other hand, if a request changes data it should always use a POST request. As I said, these are only conventions, and there is not much technical difference between them, but a very important difference is that browsers will warn the user if they try to repeat a POST -- clicking "refresh" will pop up a dialog box warning the user that this may cause an operation to be repeated, and confirming that they really want to resubmit. The browser does not show this confirmation when refreshing a GET request.
Is your form using the GET method, as suspected by @mk? If so, changing it to POST is the simplest solution, since this will at least mean that the user is warned if they try to refresh.
But a better solution is the POST+REDIRECT+GET idiom suggested by @cletus. This splits the database update (POST) and the view (GET) into two operations. Clicking refresh on the browser then merely repeats the GET, which has no side-effects.
8 سال پیش
در تاریخ 1395/12/19 منتشر شده
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