I have a web form with a detail and a list view on it, the user fills the data in the fields of the detail view and then presses the "save" button, and everything is ok for the moment.
However, if they press F5 after this operation a new record is going to be inserted in the DB, because the postback is repeated.
Does anybody knows how this could be avoided?
This will be the same for any webpage that uses a POST request for its operations.
You could stop this by using Response.Redirect("yourpage.aspx") after your save button event. This will send them to a fresh version of your page without post data in it.
Another way of doing it would be for your form to include some sort of autheticity token, such as a generated GUID. You could do some checking before processing the save request that a request using that GUID has not been issued before.
来源：https://stackoverflow.com/questions/1142740/asp-net-issue-with-f5-after-postback-because-it-does-what-it-should