How to access translation key for ActiveModel validation error?

Question

I Have a situation, where I wan't to store the translation key for a validation error in my db instead of the error message it self. Imagine the following situation:

class Car < ActiveRecord::Base
  validates_presence_of :year, :fuel
end

car = Car.new(:fuel => 'Diesel')
car.save!
#=> ActiveRecord::RecordInvalid

Now if I call:

car.errors
#=> :year=>["can't be blank"]

I get the translated error message.

Instead I would like to extract the translation key that would generate this (in this case I think it would be something like errors.messages.blank), so I can store it in my database in a different model e.g. FailedCar so I can later on generate an I18n customized form for filling in the missing information manually in a view.

UPDATE

I think it's this method that I need to hook into. I want to fetch the key and the options returned, so I can perform the translations again at a later point in time.

Answer 1

Okay I finally got it!

The solution is NOT to patch or do anything on the rails side of things - instead - the answer lies in the I18n gem.

I18n, which rails uses for translations by standard, has the ability to plugin new backends to provide more flexibility to it. In this case, the backend called metadata does exactly what I needed. When adding I18n::Backend::Simple.include(I18n::Backend::Metadata) to an initializer, it gives me the possibility of extracting all translation related information directly from the error message string by adding the method call translation_metadata.

A fantastic simple solution to a complicated problem :-)