# Any advise on exception / error handling approaches/prinicip

**URL:** <https://www.ruby-forum.com/t/any-advise-on-exception-error-handling-approaches-prinicip/87341>\
**Category:** Rails\
**Created:** [March 1, 2007, 9:49pm UTC](https://www.ruby-forum.com/t/any-advise-on-exception-error-handling-approaches-prinicip/87341 "2007-03-01T21:49:42Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![greg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/71c47a/32.png) [@greg](https://www.ruby-forum.com/u/greg)\
**Post date:** [March 1, 2007, 9:49pm UTC](https://www.ruby-forum.com/t/any-advise-on-exception-error-handling-approaches-prinicip/87341/1 "2007-03-01T21:49:42Z")

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Hi,

Can I ask for some advise re what the best practice is for handling  
exceptions & errors through my rails code from the point of view of how  
to  
display them back to the user? Some items I’d love to be covered  
include:

- is the principle that ALL exceptions (even those the application might  
not  
to be able to do anything about) should be caught and then the  
application  
then decides what text and view .rhtml? Or should the approach be to  
allow  
exceptions to occur and the rails framework to then pass this to a  
general  
error page?

- errors/exceptions that may occur in the action record / data layer -  
what  
categories of errors/exceptions here should be either (a) returned as  
call  
didn’t work or (b) exception. That is, from a best practice point of  
view  
are there 2 categories of errors/exceptions in the data layer that  
should be  
acknowledged and handed differently in terms of how they are captured  
and  
passed back to the controller layer? (e.g. catch exception and process  
in  
model code and return appropriate response, OR through to an approach  
like:  
any issue that occur in the rails or database itself that get raised as  
an  
exception, don’t try to catch them, but let the exception be thrown back  
to  
the controller (at which point my first question kicks in re whether the  
controller should catch these areas and process or let the rails  
framework  
through to a general application error page)

- where can I see all the possible errors like RoutingError,  
UnknownAction…? Is it enough to stick with the standard rails  
rescue\_action\_in\_public method (see below)?

‘404.html’)),  
“404 Not Found”)  
else  
render\_text(IO.read(File.join(RAILS\_ROOT, ‘public’,  
‘500.html’)),  
“500 Internal Error”)  
end  
end

- allocation of specific error numbers against each specific error the  
application catches/can create?

- separate log file for error details in a specific parseable/setout  
format  
(e.g. for a paging system to reference) in additional to standard log  
file  
which contains various other details like rails SQL / timing  
information, or  
full exception stack details

- an action’s render - this won’t be reached if I through an exception  
before this point or there is a rails exception I don’t catch before  
this  
point no?

- anything else related to monitoring application health?

Thanks  
Greg

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<div class="post-metadata">

**Author:** ![greg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/71c47a/32.png) [@greg](https://www.ruby-forum.com/u/greg)\
**Post date:** [March 2, 2007, 9:21pm UTC](https://www.ruby-forum.com/t/any-advise-on-exception-error-handling-approaches-prinicip/87341/2 "2007-03-02T21:21:25Z")

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[bump - still very keen to hear back if possible:)]

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<div class="post-metadata">

**Author:** ![greg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/71c47a/32.png) [@greg](https://www.ruby-forum.com/u/greg)\
**Post date:** [March 2, 2007, 9:37pm UTC](https://www.ruby-forum.com/t/any-advise-on-exception-error-handling-approaches-prinicip/87341/3 "2007-03-02T21:37:44Z")

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dont let the user see the raw error and give them a nice page,  
explaining that it aint their fault. (most users will blame there  
self’s)

There is also a nice plugin out there that will email every time a error  
occur’s