This method seems like it will be not so efficient with all the `find_by`'s.

You might consider something like this: `countries.map{|c| ratification_for_country(c).try(:to_s)}.compact.join(', ')`

Then
```
def ratification_for_country(c)
  @ratifications_by_country ||= ratifications.index_by(&:country)
  @ratifications_by_country[c]
end

And also try to ensure that when the Documents are loaded in the first place their ratifications => country are eager loaded.