Ruby on Rails i18n - Want To Translate Custom Messages in Models

Use a symbol for the message:

validates :email, presence:   true, length: { maximum: 60 },            format:     { with: valid_email_regex, message: :bad_email },            uniqueness: { case_sensitive: false } 

then in the yaml file

[lang]:  activerecord:    errors:      messages:        bad_email: "just ain't right"

If there's a translation specific to this model, it will override the general one above:

[lang]:  activerecord:    errors:      models:        model_name: # or namespace/model_name          attributes:            email:              bad_email: "model-specific message for invalid email"

If you write custom validations, add_error(:email, :bad_email) will do the lookup above, but errors[:email] << :bad_email will not.

I just walked through all this and found the rails guides for custom validators too hard-coded... I'm posting this here even though it's not exactly what you asked, but the Q title fits perfectly (which is why I read this post for my problem).

Custom validation with i18n message:

validate :something_custom?, if: :some_trigger_conditiondef something_custom?  if some_error_condition    errors.add(:some_field_key, :some_custom_msg)  endend# en.ymlactiverecord:   errors:    models:      some_model:        some_custom_msg: "This is i18n controlled. yay!"

The solution to this does not need to be custom; The format validator message already maps to the :invalid symbol. You need only set the invalid in translation.

en:  activerecord:    errors:      models:        some_model:          attributes:            email:              invalid: "FOO"

Reference: http://edgeguides.rubyonrails.org/i18n.html#error-message-interpolation