If a template causes an ActiveRecord::RecordNotFound exception to be raised, the original exception is swallowed up by ActionView and turned into an ActionView::Template::Error.
It seems that in Rails 5 there was an original_exception method but that appears to be gone in Rails 6.
I'd like to be able to inspect the cause of the ActionView::Template::Error so I can show better contextual errors.
Is there any way to do so?
If you catch the ActionView::Template::Error, there should be a #cause method defined on it which returns the original exception. Example:
begin
begin
raise ArgumentError
rescue
raise RuntimeError
end
rescue => e
puts "#{ e } caused by #{ e.cause }"
end
prints
RuntimeError caused by ArgumentError
Related
I have the following code in Rails routing:
class LegacyRedirector
InvalidUrlError = Class.new(ActionController::RoutingError)
def call(params, request)
URI.parse(request.path)
rescue URI::InvalidURIError => e
raise InvalidUrlError.new(e.message)
end
end
# routes.rb
match 'a', to: redirect(LegacyRedirector.new)
This is for catching invaild URLs. However when I test it in browser for curl, it would still display URI::InvalidURIError, not my new error class. It seems the rescue block was never reached, yet I am sure I am rescuing the correct type. How can that be?
URI::InvalidURIError at /twitter/typeahead-js/wikis/home[
=========================================================
> bad URI(is not URI?): "/twitter/typeahead-js/wikis/home["
lib/gitlab/routing.rb, line 31
------------------------------
``` ruby
> 31 URI.parse(request.path)
32 rescue URI::InvalidURIError => e
33 raise InvalidUrlError.new(e.message)
34 end
```
One possible cause could be better_errors.
If an error is raised in a rescue block, its cause would be the original error. better_errors displays that cause instead, meaning the backtrace will not be in the rescue block. This gives you the illusion that it is never rescued.
This was recently fixed, see https://github.com/BetterErrors/better_errors/pull/459 for more details
Sometimes I need to debug some nasty exception that has its backtrace hidden or truncated, like an ArgumentError without any stack trace.
I am used to debugging with byebug. The problem is that the byebug interpreter is a REPL, so it's not possible to write multiline code. I am trying to figure out how to make an inline rescue and print the backtrace from there, ie I want an inline, REPL compatible, version of
begin
....
rescue => e
puts e.backtrace.join("\n")
end
I have tried
begin; my_crashing_method.call; rescue Exception => e; puts e.backtrace; end
But that line raises a SyntaxError
*** SyntaxError Exception: (byebug):1: syntax error, unexpected keyword_rescue
rescue Exception => e
^
I'm not sure what I am missing ?
EDIT
The line above works fine on a regular IRB/Rails shell but not from a byebug shell
IRB
begin my_crashing_method.call; rescue Exception => e; puts e.backtrace end
Stack Trace shows successfully
Byebug
(byebug) begin; my_crashing_method.call; rescue Exception => e; puts e.backtrace
*** SyntaxError Exception: (byebug):1: syntax error, unexpected end-of-input
begin
^
nil
*** NameError Exception: undefined local variable or method `my_crashing_method' for #<StaticPagesController:0x007fae79f61088>
nil
*** SyntaxError Exception: (byebug):1: syntax error, unexpected keyword_rescue
rescue Exception => e
^
nil
*** NameError Exception: undefined local variable or method `e' for #<StaticPagesController:0x007fae79f61088>
nil
When you enter multiple lines ruby code or in a single line on byebug, you need to escape the semicolon using backlash. The following should do the trick.
begin\; my_crashing_method.call\; rescue Exception => e\; puts e.backtrace end
https://github.com/deivid-rodriguez/byebug/blob/master/GUIDE.md#command-syntax
I'm trying to figure out the best way to catch a specific error thrown AND the error's message in Ruby on Rails. My use case is that I encounter a timeout error every now and then which is thrown with a general error and I want to treat the timeout error differently than other errors within the same general error. I'm not sure what other type of errors could be thrown in the general error but I assume more of them exist. I have some sample code below of how I'm currently handling it, but I was thinking there might be a better way which I haven't found yet?
tries = 0
begin
tries += 1
<code>
rescue Foo::Bar => e
case e.to_s
when 'More specific timeout error message'
retry unless tries >= 5
else
# Let me see other error messages
log.info("Error: #{e.to_s}")
end
end
You can use multi rescue, to handle different errors.
begin
# DO SOMETHING
rescue Net::Timeout => e # change it to the error your want to catch, check the log.
# handle it
rescue SyntaxError => e # just an example
# handle it
rescue => e # any error that not catch by above rescue go here.
# handle it
end
Read more:
http://phrogz.net/programmingruby/tut_exceptions.html
You can try Rollbar, it help report error on production.
Take a look at retriable gem. It seems like a good fit for what you're proposing. Usually you'd rescue from an specific error type, but retriable also gives you the choice to rescue based on the error message.
begin
Retriable.retriable on: { Foo::Bar => /More specific timeout error message/ }, tries: 3 do
# will retry if an error of type Foo::Bar is raised
# and its message matches /More specific timeout error message/
# code here...
end
rescue => e # rescue for everything else
puts e.message # same as e.to_s
end
In my Rails 3 app, I am fetching path_info by:
Rails.application.routes.recognize_path(url, { :method => request.request_method }) rescue {}
If a crawler hits a URL like "http://localhost:3000/admin_", the above code raises following error:
LoadError: Expected /Users/user/myRailsApp/app/controllers/admin_controller.rb to define Admin_Controller
from /Users/user/.rvm/gems/ree-1.8.7-2012.02/gems/activesupport-3.0.20/lib/active_support/dependencies.rb:492:in `load_missing_constant'
I have two questions:
Why is rescue not working? If I change it to rescue LoadError => e, exception is handled gracefully.
Is there any other alternative rather than rescuing such exception(s)?
If you omit the exception type, by default rescue will rescue only StandardError exceptions and subclasses.
LoadError doesn't inherit from StandardError:
LoadError.ancestors
=> [LoadError, ScriptError, Exception, Object, Kernel, BasicObject]
Therefore, the one-line rescue pattern doesn't work with a LoadError.
When exiting a Rails app using raise or fail, how to prevent the backtrace from being displayed?
Tried using back_trace_limit but it only seems to work for the console...?
You have total control over the backtrace returned with an exception instance by using its set_backtrace method. For example:
def strip_backtrace
yield
rescue => err
err.set_backtrace([])
raise err
end
begin
strip_backtrace do
puts 'hello'
raise 'ERROR!'
end
rescue => err
puts "Error message: #{err.message}"
puts "Error backtrace: #{err.backtrace}"
end
Output:
hello
Error message: ERROR!
Error backtrace: []
The strip_backtrace method here catches all errors, sets the backtrace to an empty array, and re-raises the modified exception.