Translating locales for Rails model errors

As you may know you can specify own message for Rails model validation error like this:

# app/models/user.rb
class User < ActiveRecord::Base
  PASSWORD_FORMAT = /\A.*(?=.{8,})(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).*\z/

  validates_format_of :password, :with => PASSWORD_FORMAT,
    message: "Must include uppercase & number"

end

…which is good until your application reach the stage when you want to support multiple languages.

I’ve seen some developers do something like this:

# app/models/user.rb
  # ...
  validates_format_of :password, :with => PASSWORD_FORMAT,
    message: I18n.t('wrong_password')
  # ...
end

…which is kinda acceptable if you doing something super-ninja like, but for 99% of cases there is already built in Rails solution, so why not to use it:

# app/models/user.rb
  # ...
  validates_format_of :password, :with => PASSWORD_FORMAT,
  # ...

# config/locales/en.yml
en:
  activerecord:
    errors:
      models:
        user:
          attributes:
            password:
              invalid: 'Must include uppercase & number'

• for validates_presence_of keyword you can use blank
• for validates_length_of keyword you can use too_short or too_long
• for validates_uniqueness_of keyword you can use taken

You can find other keys in this Rails error message interpolation table

As demonstrated in official Active Record locales guide there is a certain locales fallback tree for Active Record:

activerecord.errors.models.admin.attributes.name.blank
activerecord.errors.models.admin.blank
activerecord.errors.models.user.attributes.name.blank
activerecord.errors.models.user.blank
activerecord.errors.messages.blank
errors.attributes.name.blank
errors.messages.blank

You can use it for example if you want certain translation to apply on attribute password for all models:

# config/locales/en.yml
en:
  errors:
   attributes:
     password:
       invalid: 'Wrong password format !!'

One interesting thing I discovered is that for this to work errors key must be before activerecord key in your locales file otherwise they wont work. But I’m not 100% sure on that (may be caused one of gems I use in the project):

# config/locales/en.yml
en:
  errors:
   attributes:
     # ...
  activerecord:
    # ...  

For those that need more flexibility there is option to specify your own symbols (as demonstrated in this SO answer )

# app/models/user.rb
  # ...
  validates_format_of :password, :with => PASSWORD_FORMAT,
    message: :foo
  # ...

which will point to: en.activerecord.errors.models.user.attributes.password.foo

# config/locales/en.yml
en:
  activerecord:
    errors:
      models:
        user:
          attributes:
            password:
              foo: "Are U bannanas ? O_O"

…same fallback rules should apply.

source:

• http://stackoverflow.com/questions/4451076/rails-internationalization-i18n-in-model-validations-possible-or-not
• http://guides.rubyonrails.org/i18n.html#translations-for-active-record-models

published: 2014-05-29

keywords: I18n, locales, internationalization, Ruby on Rails 4, Rails 3, Ruby 2.1.1, models, errors