# Auto\_complete and HTTP errors **URL:** \ **Category:** Rails\ **Created:** [November 28, 2008, 9:44am UTC](https://www.ruby-forum.com/t/auto-complete-and-http-errors/154362 "2008-11-28T09:44:39Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Cameron\_McCloud](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/e274bd/32.png) [@Cameron\_McCloud](https://www.ruby-forum.com/u/Cameron_McCloud)\ **Post date:** [November 28, 2008, 9:44am UTC](https://www.ruby-forum.com/t/auto-complete-and-http-errors/154362/1 "2008-11-28T09:44:39Z")
Hi, I have a simple example in Rails 2.1.2, 2.2.2 using the auto\_complete plugin. It works wonderfully. However, I was wondering how it would handle errors. For example, if for some reason a person couldn’t be found, the HTTP request will come back with a 404 def auto\_complete\_for\_people\_foo # Cause a deliberate error people = Person.find(22222) # doesn’t exist . . . end Or there might be a syntax error in the code and we get a 500 error back. def auto\_complete\_for\_people\_foo # Cause a deliberate error asflksajflasjlf # Not valid Ruby code . . . end For other AJAX functionality in our application (e.g. form\_remote\_tag) we have global AJAX repsonders as follows: Ajax.Responders.register({ onComplete: function(transport) { console.info(“COMPLETE”); Element.hide(‘spinner’); if (transport.transport.status == 0 || transport.transport.status == 12029) { // Lost connection as reported in Firefox (0) or IE (12029) alert(“The connection with the server has been lost.”); console.info(“LOST CONNECTION”); } else if (transport.transport.status != 200 ) { alert(String.format(“The server has reported an error with code {0}”, transport.transport.status)); console.info(“ERROR”); } }, onCreate: function() { Element.show(‘spinner’); console.info(“LOADING…”); } }); For auto\_complete, the onCreate callback gets invoked, but the onComplete one never does. I’ve checked this in Firebug - I can see the 404 or 500 POST errors, but I the Does anyone have any ideas or areas they can point me to? TIA Cam. ---
**Author:** ![Cameron\_McCloud](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/e274bd/32.png) [@Cameron\_McCloud](https://www.ruby-forum.com/u/Cameron_McCloud)\ **Post date:** [November 28, 2008, 9:49am UTC](https://www.ruby-forum.com/t/auto-complete-and-http-errors/154362/2 "2008-11-28T09:49:56Z")
The last bit should have read: For auto\_complete, the onCreate callback gets invoked, but the onComplete one never does. I’ve checked this in Firebug - I can see the 404 or 500 POST errors, but the onComplete responder never kicks in. ---
**Author:** ![Cameron\_McCloud](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/e274bd/32.png) [@Cameron\_McCloud](https://www.ruby-forum.com/u/Cameron_McCloud)\ **Post date:** [November 28, 2008, 10:48am UTC](https://www.ruby-forum.com/t/auto-complete-and-http-errors/154362/3 "2008-11-28T10:48:38Z")
On Nov 28, 8:48 am, Cameron McCloud [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > The last bit should have read: > > For auto\_complete, the onCreate callback gets invoked, but the > onComplete one never does. I’ve checked this in Firebug - I can see > the 404 or 500 POST errors, but the onComplete responder never kicks > in. That’s weird. Prototype itself uses that to maintain the value of Ajax.activeRequestCount Is that value going up and down as it should? If you look at the code, one thing that would screw this over would be if the onComplete callback for that particular request threw an exception Fred ---
**Author:** ![Cameron\_McCloud](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/e274bd/32.png) [@Cameron\_McCloud](https://www.ruby-forum.com/u/Cameron_McCloud)\ **Post date:** [November 28, 2008, 11:22am UTC](https://www.ruby-forum.com/t/auto-complete-and-http-errors/154362/4 "2008-11-28T11:22:07Z")
On Nov 28, 10:16 am, Cameron McCloud [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > When I CTRL-F5 to start off afresh, the Ajax.activeRequestCount is 0. > > If I type in my name very slowly into the edit box, the count is now 7 > > - it is never decremented. When my code is running normally (i.e. I’m > not deliberately forcing errors), the count always returns to zero. So it’s not just your responder 🙂 Is your ‘normal’ onComplete throwing an exception a possibility ? ( you could put a breakpoint in dispatchException). Fred ---
**Author:** ![Cameron\_McCloud](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/e274bd/32.png) [@Cameron\_McCloud](https://www.ruby-forum.com/u/Cameron_McCloud)\ **Post date:** [November 28, 2008, 11:16am UTC](https://www.ruby-forum.com/t/auto-complete-and-http-errors/154362/5 "2008-11-28T11:16:50Z")
When I CTRL-F5 to start off afresh, the Ajax.activeRequestCount is 0. If I type in my name very slowly into the edit box, the count is now 7 - it is never decremented. When my code is running normally (i.e. I’m not deliberately forcing errors), the count always returns to zero. On Nov 28, 9:48 am, Frederick C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![Cameron\_McCloud](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/e274bd/32.png) [@Cameron\_McCloud](https://www.ruby-forum.com/u/Cameron_McCloud)\ **Post date:** [November 28, 2008, 12:13pm UTC](https://www.ruby-forum.com/t/auto-complete-and-http-errors/154362/6 "2008-11-28T12:13:51Z")
I put a breakpoint on dispatchException and it hits that with the following: TypeError: element.hasClassName is not a function message=element.hasClassName is not a function. The line that triggered the exception is in prototype.js line 1322 (Latest Prototype.js 1.6.0.3) However, I also get this even if I don’t have any Ajax responders set up. On Nov 28, 10:24 am, Cameron McCloud [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![Cameron\_McCloud](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/e274bd/32.png) [@Cameron\_McCloud](https://www.ruby-forum.com/u/Cameron_McCloud)\ **Post date:** [November 28, 2008, 12:32pm UTC](https://www.ruby-forum.com/t/auto-complete-and-http-errors/154362/7 "2008-11-28T12:32:39Z")
On Nov 28, 11:12 am, Cameron McCloud [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I put a breakpoint on dispatchException and it hits that with the > following: > > TypeError: element.hasClassName is not a function > message=element.hasClassName is not a function. > > The line that triggered the exception is in prototype.js line 1322 > (Latest Prototype.js 1.6.0.3) You need to crawl up the stack to see who called that. My guess is that your onComplete callback does something that doesn’t make sense when the response wasn’t a 200. Fred ---
**Author:** ![Cameron\_McCloud](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/e274bd/32.png) [@Cameron\_McCloud](https://www.ruby-forum.com/u/Cameron_McCloud)\ **Post date:** [November 28, 2008, 12:46pm UTC](https://www.ruby-forum.com/t/auto-complete-and-http-errors/154362/8 "2008-11-28T12:46:10Z")
On reading the Prototype docs (something I should have done earlier), there’s another Responder for handling exceptions - onException. This does get called and through it I can let the user know that something went wrong. It doesn’t seem to tell me if the problem is a 404, 500 and I can’t tell if the server is no longer available, but it’s a start. Thanks for all your help Frederick. Cameron. On Nov 28, 11:12 am, Cameron McCloud [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![Cameron\_McCloud](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/e274bd/32.png) [@Cameron\_McCloud](https://www.ruby-forum.com/u/Cameron_McCloud)\ **Post date:** [November 28, 2008, 11:25am UTC](https://www.ruby-forum.com/t/auto-complete-and-http-errors/154362/9 "2008-11-28T11:25:39Z")
Strangely enough when the focus is on the auto complete edit field in Firefox and I ALT-TAB to my editor, another AJAX request is made, but this time the onComplete gets called and I get the alert message box On Nov 28, 10:21 am, Frederick C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)