CGI and locking

Ryszard has asked for the wisdom of the Perl Monks concerning the following question:

I'm in the unfort situation where i have a web interface and a link that will execute a heavy and long query.

What I dont want is the user to double click the link, or click many times if the query doesnt return "fast enuff"

I've got some ideas for a locking mechanism, however I'm also after any idea's/experience others may have.

Comment on CGI and locking

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Re: CGI and locking by rob_au (Abbot) on May 15, 2002 at 09:56 UTC
Not surprisingly merlyn has written something on this already ... Check out Highlander - allow only one invocation at a time of an expensive CGI script which he also wrote about in one of his Web Techniques columns.	[reply]
Re: Re: CGI and locking by perrin (Chancellor) on May 15, 2002 at 13:35 UTC
Actually, I think this column is more appropriate.	[reply]
Re: CGI and locking by zakb (Pilgrim) on May 15, 2002 at 12:05 UTC
You can do this reasonably reliably client-side with Javascript too... I've written the below from memory, I have used something similar in the past for exactly this situation... `<script language="javascript"> var submitCount = 0; function doSubmit() { if (submitCount == 0) { submitCount++; document.form1.submit(); } else { alert("Please wait, lengthy query executing..."); } } </script> ... <form name=...> ... <input type="button" onClick="doSubmit();"> </form> ...` [download] Update: andye beat me to it! This approach will only work if your clients have Javascript enabled.	[reply] [d/l]
Re: CGI and locking by andye (Curate) on May 15, 2002 at 11:59 UTC
One neat trick: use Javascript to deactivate the submit button on form submit. Obviously you need to do something on the server-side as well - because not everyone has Javascript switched on - but this method provides immediate feedback to (most) users and prevents them from even trying to double-submit. hth, andy.	[reply]