discourse/app/models/translation_override.rb

class TranslationOverride < ActiveRecord::Base
  validates_uniqueness_of :translation_key, scope: :locale
  validates_presence_of :locale, :translation_key, :value

  def self.upsert!(locale, key, value)
    params = { locale: locale, translation_key: key }
    row_count = where(params).update_all(value: value)
    create!(params.merge(value: value)) if row_count == 0
  end

end