Translate Rails model association - not working - ruby-on-rails

Question

Anyone has some tips as how to translate model associations in Rails?
For example: I have a Person model, which can have many Phone. However, a Person needs to have at least one Phone. I'm not able to translate that validation. The best I could do was this:
validates_presence_of :phones, :message => "At least one phone is required."
And on my YAML, I replaced this line to omit the %{attribute}:
format: ! '%{message}'
This way only my message is displayed, and I avoid the un-translated field name to be displayed.
This is causing me a lot of headache, because some gems simply don't allow me to pass :message => "something describing the error", so I wanted to configure all the error messages through my YAML.
Also, with some models I'm able to translate their attributes, while with others I'm not. For example:
activerecord:
attributes:
additional_info:
account_manager: "Manager"
This works. I can see on my form "Manager". However, when this field has an error, Rails will display it as "Additional info account manager can't be blank".
I tried this:
activerecord:
errors:
models:
additional_info:
attributes:
account_manager: "Manager"
But no luck.
I did read the docs, but no clue on why it's happening.

Answer 1

Here are the valid key paths for Rails 4.1:
# Basic Attribute on Model
activerecord:
attributes:
#{model_class.model_name.i18n_key}:
#{attribute_name}:
"Localized Value"
# Attribute on Nested Model
activerecord:
attributes:
#{model_class.model_name.i18n_key}/#{association_name}:
#{attribute_name}:
"Localized Value"
#{association_name}:
#{attribute_name}:
"Fallback Localized Value"
So, given this model (which has the i18n_key of :person):
class Person
has_many :friends
end
You'd have these locale definitions:
activerecord:
attributes:
person:
first_name:
"My Name"
person/friends:
first_name:
"My Friend's Name"
friends:
first_name:
"A Friend's Name"
If your model is a namespace, such as:
class MyApp::Person
has_many :friends
end
the i18n_key becomes :my_app/person and your / key starts to wear out:
activerecord:
attributes:
my_app/person:
first_name:
"My Name"
my_app/person/friends:
first_name:
"My Friend's Name"
friends:
first_name:
"A Friend's Name"

Answer 2

Rails 3.2 has changed this behavior. The way I've posted before is deprecated.
Now, in order to translate associations, there is the need to add a slash (instead of nesting everything). So instead of this:
activerecord:
attributes:
person:
additional_info:
account_manager: "Manager"
The correct now is:
activerecord:
attributes:
person:
additional_info/account_manager: "Manager"
Also, I figured out that has_many associations are being translated differently from that. If you want to translate those, the following example may help:
activerecord:
attributes:
emails:
address: "E-mail field"
Instead of the model name, like I did above, you need to pass the association name, in this case emails.
Check this comment and pull request for more info:
https://github.com/rails/rails/commit/c19bd4f88ea5cf56b2bc8ac0b97f59c5c89dbff7#commitcomment-619858
https://github.com/rails/rails/pull/3859