Exception Notification Plugin Question

Rails
1

Hi,

I have two questions re the Exception Notifier plugin (i.e. which you
install via “ruby script/plugin install exception_notification”)

Q1 - In it’s current setup (where it uses /public/500.html) is it
possible
to remove the “Status: 500 Internal Server Error Content-Type:
text/html”
text which seems to mysteriously get place at the top of the page?

Q2 - What’s the best way to add dynamic text to the error page? Should
I
change the following section of the plug-in to point to a normal Rails
action/rhtml view? But if I do this would this be making the design
brittle, i.e. what happens if there is a Rails internal issue itself
which
could mean it’s not possible for the error action/rhtml view to work?
…
def render_500
respond_to do |type|
type.html { render :file => “#{RAILS_ROOT}/public/500.html”,
:status
=> “500 Error” }
.
.
…

Tks
Greg

2

PS. In fact I think I may have been the scenario for which Exception
Notification was targeted at. Would the the below be correct:

[1] Uncaught Exception (i.e. not expected)
=> Exception Notification handles these / sends email

[2] Caught Exceptions (understood issue - can offer specific user
advice)
=> Use of custom application exception, global handler which can:
(a) send email alert, (b) display dynamic text in custom
application
error view.rhtml. That is concept is you can throw a custom app
exception anywhere in a model/controller and not have to worry
about
adding a handler/view.
=> QUESTION 1 - Where/how to catch such exception in the one spot and
and handle this? Extend Exception Notification plugin?

[3] Complex Business Rules (in Model, but not per field)
=> Use of Rails Validation framework but via adding validations
to :base within the error object

[4] Per Field Validations
=> Use of Rails Validations

3

I would also be interested to know how to do what Greg has mentioned.

With my web application, it would help me to pindown the issue if I know
the ID of the record in question. I’d like to add this to the exception
error.

Does anyone know the best way to do this?

Xin

Greg H. wrote:

Hi,

I have two questions re the Exception Notifier plugin (i.e. which you
install via “ruby script/plugin install exception_notification”)

Q1 - In it’s current setup (where it uses /public/500.html) is it
possible
to remove the “Status: 500 Internal Server Error Content-Type:
text/html”
text which seems to mysteriously get place at the top of the page?

Q2 - What’s the best way to add dynamic text to the error page? Should
I
change the following section of the plug-in to point to a normal Rails
action/rhtml view? But if I do this would this be making the design
brittle, i.e. what happens if there is a Rails internal issue itself
which
could mean it’s not possible for the error action/rhtml view to work?
…
def render_500
respond_to do |type|
type.html { render :file => “#{RAILS_ROOT}/public/500.html”,
:status
=> “500 Error” }
.
.
…

Tks
Greg

4

Xin,

I’ve ended up doing the following so far, some of which are adjustments
to
Jamis B.'some “Exception Notification” plugin. I’m still optimizing
this
for my own usage as I go. Hope this helps (any ideas/feedback welcome):

Usage:
if error_situation_occurs
raise Error.new( “Message to User Here - Will be shown on error page”,
“Additional message that will go to log file for
developers”,
Logger::ERROR)
end

Features:

  • Separate user & developer messages
  • Do not have to catch such errors back in controller or views as the
    below-mentioned rails rescue frame work will handle (i.e. less work,
    cleaner
    code)
  • Just need to raise the Error exception which then
    triggers/implies/carries
    out:
    (a) appropriate email message to user
    (b) developer specific additional message to logs
    © severity of log entry raised
    (b) triggers Email/SMS alert based on severity of the error (use of
    Ruby
    Logger severity levels)

class Error < RuntimeError
attr :developer_message
attr :severity

def initialize(user, dev=nil, sev=Logger::FATAL)
super user # Use normal exception parameter
for
User Message
@developer_message = dev || user # Set developer focused message
@severity = sev
end
end

def rescue_action_in_public(exception) # Override this Rails method
case exception
when *exceptions_to_treat_as_404
render_404
else
if exception.instance_of?(Error) # Added by Greg
# Custom Error (caught)
render_custom_error
case (exception.severity)
when Logger::FATAL
# trigger an email/sms for FATALs
send_notification(exception)
else
# no emails/sms otherwise - future step: have this
configurable in
environment.rb
end
else
# 500 Error (not caught)
render_500
send_notification(exception)
end
end
end

def render_custom_error
respond_to do |type|
type.html { render :template => “error/custom_500_error”}
type.all { render :nothing => true, :status => “500 Error” }
end
end

def log_error(exception) #:doc: # Override this Rails method
ActiveSupport::Deprecation.silence do
if ActionView::TemplateError === exception
logger.fatal(exception.to_s)
else
if exception.instance_of?(Error) # Added by Greg - logs the
User
Message, Log/Developer Message and limits stack trace to first 3 lines
# Custom Error (caught)
logger.error("#{exception.developer_message}\n" +
" Exception Class:#{exception.class}\n" +
" User Msg: #{exception.message}\n" +
" Backtrace:\n " + clean_backtrace(exception)[0…2].join("\n
“) + “\n\n”
)
else
logger.fatal(”#{exception.developer_message}\n" +
" Exception Class:#{exception.class}\n" +
" Backtrace:\n " + clean_backtrace(exception)[0…2].join("\n
") + “\n\n”
)
end
end
end
end