How to empty ASP.net postback cache?

Question

I have an asp.net webform on which I click a button to fill server side C# variables. If I am correct this occurs by an HTTP POST (a postback since I resend the user supplied data with the webform back to the server using the body of the HTTP request)

When the server recieves the postback, it will send some instructions bac to the client (for instance "display an alert message").

My problem here is that when I refresh (F5) the webform, what ever action that was performed last is reexecuted. Hence, a postback is reexecuted when I refresh the page, thus triggering a response from the server.

How can I disable this behavior ? By this I mean that how could hitting F5 just reload the page as if it was the first time (I guess all my code behind variables will be restoredto default too...)

Hate to say this but web forms developers are kind of stuck with that behavior. The only way to avoid it is to make sure the page the user is viewing resulted from a GET and not a POST. Quite easy in MVC but very hard with web forms. — John Wu, Mar 14 '17 at 22:55
@JohnWu Don't know much about MVC now...but do you have any idea of how I could "catch" a F5 ? Then I'd deal with it manually — Kurt Miller, Mar 14 '17 at 23:23

score 2 · Answer 1 · answered Mar 14 '17 at 22:58

2

This is default browser behavior. F5 will always trigger a repost if the form was submitted (PostBack).

You can get around this behavior by redirecting to the same page again after a PostBack

Response.Redirect(Request.RawUrl, false);

But if you use this, you cannot get a response to the client like you normally would. Only setting a Session before the redirect and then deal with it on the page after redirect would be the only way to get a response from the server to the client.

Better is making sure a repost will not create any problems, like duplicate database entries etc.

answered Mar 14 '17 at 22:58

VDWWD

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Yes. Dealing with duplicate helps. But is it not possible to make F5 restore the whole page (including the code behind) as if it was the 1st load ? – Kurt Miller Mar 14 '17 at 23:19
Or maybe do you have any idea of how I could "catch" a F5 ? Then I'd deal with it manually – Kurt Miller Mar 14 '17 at 23:23
No, as John Wu already mentioned it's an integral part of aspnet webforms.The only thing that comes close is using `UpdatePanels`. – VDWWD Mar 14 '17 at 23:24
Thank you. I'll look into that. – Kurt Miller Mar 14 '17 at 23:36

How to empty ASP.net postback cache?

1 Answers1