```ruby
class I18nContentTranslation < ActiveRecord::Base
  def self.existing_languages
    self.select(:locale).uniq.map{ |l| l.locale.to_sym }.to_a
  end
end
```

Fix deprecation warning for `.uniq` usage
user
```ruby
class I18nContentTranslation < ActiveRecord::Base
  def self.existing_languages
    self.select(:locale).distinct.map { |l| l.locale.to_sym }.to_a
  end
end
```
assistant