resending GET every time... BAD

[Troy]

Hi there-

I have a web application to maintain and one of the problems I am
dealing with is this:

1) user arrives at a page (URL=A) and it displays a list of stuff.
2) User clicks submit on a form pertaining to an item in the list.
2) Form is submitted, server performs operation, server sends back
same page with updated data.(URL=B)
3) User clicks reload
4) The form is submitted again (thanks to URL B), server tries to
perform same operation and fails.

Now I could use a POST, but then I'd get that annoying resubmit post
dialog and that's just as bad. I've seen stuff like, "DO NOT CLICK
THIS BUTTON MORE THAN ONCE" warnings before, but that won't fly with
my boss.

I know what the problem is, the URL is altered after I submit (which
includes a command that tells the server what action to perform).
When they reload, URL B is reissued. I need to replace URL B with the
original URL A. then the problem becomes, how do I save URL A int he
first place?

How can I get the form to submit only once?

thanks!
troy

[Jim Dabell]

Troy wrote:

Hi there-

I have a web application to maintain and one of the problems I am
dealing with is this:

1) user arrives at a page (URL=A) and it displays a list of stuff.
2) User clicks submit on a form pertaining to an item in the list.
2) Form is submitted, server performs operation, server sends back
same page with updated data.(URL=B)
3) User clicks reload
4) The form is submitted again (thanks to URL B), server tries to
perform same operation and fails.

Now I could use a POST, but then I'd get that annoying resubmit post
dialog and that's just as bad. I've seen stuff like, "DO NOT CLICK
THIS BUTTON MORE THAN ONCE" warnings before, but that won't fly with
my boss.

[snip]

The problem is that you have ignored section 9.1 of RFC 2616 (the HTTP 1.1
specification).

"In particular, the convention has been established that the GET and HEAD
methods SHOULD NOT have the significance of taking an action other than
retrieval. These methods ought to be considered "safe"."

-- <URL:http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.1>

A common way of constructing an interface like this is to have two files, a
'view' and a 'controller'. The view grabs the information out of the
database or wherever, and displays it to the user. That is all. The
controller updates the database and redirects to the view. That is all.

Now you can use POST with the forms, and the only page the user will attempt
to reload is the view page, which is now safe. If by some chance the user
does attempt to reload the action page, they will get a warning off their
browser (as they should). The warnings of common browsers aren't very
clear, but usually people figure out enough to hit cancel and then the back
button.
--
Jim Dabell

[Jonathan Snook]

"Troy" <tr**@morpheus.net> wrote in message

I know what the problem is, the URL is altered after I submit (which
includes a command that tells the server what action to perform).
When they reload, URL B is reissued. I need to replace URL B with the
original URL A. then the problem becomes, how do I save URL A int he
first place?

How can I get the form to submit only once?

This is more of a server-side programming issue and you may have better luck
in a forum that deals with the language you're developing in.

My thought is, URL B should be able to render with only the information that
appears in the querystring. If there's a form on the page that a user can
resubmit, you should be able to recreate it to contain the values that would
have been used before the user submitted it (URL A).

If the issue is that once URL A is submitted, it performs an action that
should only happen once (e.g: charging a credit card) then you'd need to
track whether that particular user (using a session id) has already
performed the action before performing it again.

Good luck,

Jonathan
--
http://www.snook.ca/

[Nick Kew]

In article <MG**********************@news01.bloor.is.net.cabl e.rogers.com>, one of infinite monkeys
at the keyboard of "Jonathan Snook" <go***************@snook.ca> wrote:

This is more of a server-side programming issue and you may have better luck
in a forum that deals with the language you're developing in.

Indeed, ISTR putting it in the FAQ for that group some years ago.

--
Nick Kew

In urgent need of paying work - see http://www.webthing.com/~nick/cv.html