Translation Fields

translation_fields.ex

defmodule TranslationFields do
  @moduledoc """
  Usage:
      defmodule Product do
        use TranslationFields
        
        @translated_locales ~w(en fr)
        @translated_fields ~w(name description)

        schema "products" do
          field :price, :integer
          field :sku, :string
          field :slug, :string

          translation_fields()
          timestamps()
        end

    Then for each `@translated_fields` it will define one persistent field containing the translations
    as a map (named `fieldname_translations`), and virtual attributes for each locale (named `fieldname_localename`).

    ie.: `%Product{description_en: nil, description_fr: nil, description_translations: nil, name_en: nil, name_fr: nil, name_translations: nil, ...}
  """
  defmacro __using__(_opts) do
    quote do
      import TranslationFields

      @translated_locales ~w()
      @translated_fields ~w()
    end
  end

  defmacro translation_fields do
    quote do
      Enum.each(@translated_fields, fn(field) ->
        field :"#{field}_translations", :map

        Enum.each(@translated_locales, fn(locale) ->
          field :"#{field}_#{locale}", :string, virtual: true
        end)
      end)
    end
  end
end