[Rails] Exception + rescue/raise

Syntax Does "raise" trigger exception?Rescue Rescue all exceptions Rescue from StandardError Raise Raise a single string Related Articles

Syntax

begin
   # raise 'A test exception.'
   puts "I'm not raising exception"
rescue Exception => e
   puts e.message
   puts e.backtrace.inspect
else
   puts "Congratulations-- no errors!"
ensure
   puts "Ensuring execution"
end

# I'm not raising exception
# Congratulations-- no errors!
# Ensuring execution

Does "raise" trigger exception?

Short answer: yes

Long answer: what exception are you raising? what exception are you capturing?

Rescue

Rescue all exceptions

rescue Exception

💡

Rescue everything is a bad idea because it includes SyntaxError, LoadError, and Interrupt.

Rescuing Interrupt prevents the user from using CTRLC to exit the program.

Rescuing SignalException prevents the program from responding correctly to signals. It will be unkillable except by kill -9.

Rescue from `StandardError`

rescue without a parameter just rescues exceptions that inherit from StandardError

These three all rescue from StandardError.

begin
  # iceberg!
rescue
  # lifeboats
end

begin
  # iceberg!
rescue => e
  # lifeboats
end

begin
  # iceberg!
rescue StandardError => e
  # lifeboats
end

Raise

raise exception-type "exception message" condition

Raise a single string

With a single String argument, raises a RuntimeError with the string as a message.

(RuntimeError inherit from StandardError)

raise "this is an error"

https://www.geeksforgeeks.org/raising-exceptions-in-ruby/

https://stackoverflow.com/questions/3168160/begin-rescue-not-catching-error

https://stackoverflow.com/questions/10048173/why-is-it-bad-style-to-rescue-exception-e-in-ruby

https://www.mikeperham.com/2012/03/03/the-perils-of-rescue-exception/

https://www.geeksforgeeks.org/ruby-exceptions/?ref=rp