Update Translator module

The translator module does not require to be passed the name of the
translation container field. The test have also been updated to reflect
this change.

lib/trans/translator.ex

@@ -102,9 +102,12 @@ defmodule Trans.Translator do
       "Cómo escribir un corrector ortográfico"
 
   """
-  def translate(struct, locale, field, opts \\ []) when is_map(struct) do
-    translation_container = opts[:container] || :translations
-    translated_field = with {:ok, all_translations} <- Map.fetch(struct, translation_container),
+  def translate(struct, locale, field) when is_map(struct) do
+    # Check if the struct is a map or an actual struct.
+    # If it is a struct, check if it uses Trans and if the field is among the translatable fields
+    # Look for `translations` and `"translations"
+    raise_if_untranslatable(struct, field)
+    translated_field = with {:ok, all_translations} <- Map.fetch(struct, translation_container(struct)),
                             {:ok, translations_for_locale} <- Map.fetch(all_translations, to_string(locale)),
                             {:ok, translated_field} <- Map.fetch(translations_for_locale, to_string(field)),
       do: translated_field
@@ -114,5 +117,12 @@ defmodule Trans.Translator do
     end
   end
 
+  defp translation_container(%{translations: _}), do: :translations
+  defp translation_container(%{"translations" => _}), do: "translations"
+  defp translation_container(_) do
+    raise ArgumentError, message: "Translation container not found. You must define a 'translations' field into your map or struct so it can be used by Trans."
+  end
+
+  defp raise_if_untranslatable(_struct, _field), do: nil
 
 end

test/translator_test.exs

@@ -8,21 +8,27 @@ defmodule TranslatorTest do
 
   test "retrieve translation for existing attribute" do
     article = build(:article)
-    fr_body = Translator.translate(article, :fr, :body, container: :test_translation_container)
-    assert fr_body == article.test_translation_container["fr"]["body"]
+    fr_body = Translator.translate(article, :fr, :body)
+    assert fr_body == article.translations["fr"]["body"]
   end
 
   test "fallback to default value when no translation available" do
     article = build(:article)
     # Since we don't have a "de" translation, it will return the default value'
-    body = Translator.translate(article, :de, :body, container: :test_translation_container)
+    body = Translator.translate(article, :de, :body)
     assert body == article.body
   end
 
   test "raise error wen translating an untraslatable attribute" do
     article = build(:article)
     assert_raise KeyError, fn ->
-      Translator.translate(article, :es, :fake_attr, container: :test_translation_container)
+      Translator.translate(article, :es, :fake_attr)
+    end
+  end
+
+  test "raise error when no translation container" do
+    assert_raise ArgumentError, fn ->
+      Translator.translate(%{}, :es, :fake_attr)
     end
   end
 end