Merge pull request rails#35424 from Korri/validation-rules-locale-fallback

Fall back to parent locale before falling back to the :errors namespace

Author: rafaelfranca

activemodel/CHANGELOG.md

@@ -1,3 +1,27 @@
+
+*   Changed how validation error translation strings are fetched: The new behaviour
+    will first try the more specific keys, including doing locale fallback, then try
+    the less specific ones.
+    
+    For example this is the order keys will now be tried for a `blank` error on a
+    `product`'s `title` attribute with current locale set to `en-US`:
+ 
+        en-US.activerecord.errors.models.product.attributes.title.blank
+        en-US.activerecord.errors.models.product.blank
+        en-US.activerecord.errors.messages.blank
+        
+        en.activerecord.errors.models.product.attributes.title.blank
+        en.activerecord.errors.models.product.blank
+        en.activerecord.errors.messages.blank
+        
+        en-US.errors.attributes.title.blank
+        en-US.errors.messages.blank
+        
+        en.errors.attributes.title.blank
+        en.errors.messages.blank
+ 
+    *Hugo Vacher*
+
 ## Rails 6.0.0.beta2 (February 25, 2019) ##
 
 *   Fix date value when casting a multiparameter date hash to not convert

activemodel/lib/active_model/errors.rb

@@ -479,6 +479,14 @@ def full_message(attribute, message)
     # * <tt>errors.messages.blank</tt>
     def generate_message(attribute, type = :invalid, options = {})
       type = options.delete(:message) if options[:message].is_a?(Symbol)
+      value = (attribute != :base ? @base.send(:read_attribute_for_validation, attribute) : nil)
+
+      options = {
+        model: @base.model_name.human,
+        attribute: @base.class.human_attribute_name(attribute),
+        value: value,
+        object: @base
+      }.merge!(options)
 
       if @base.class.respond_to?(:i18n_scope)
         i18n_scope = @base.class.i18n_scope.to_s
@@ -487,6 +495,11 @@ def generate_message(attribute, type = :invalid, options = {})
             :"#{i18n_scope}.errors.models.#{klass.model_name.i18n_key}.#{type}" ]
         end
         defaults << :"#{i18n_scope}.errors.messages.#{type}"
+
+        catch(:exception) do
+          translation = I18n.translate(defaults.first, options.merge(default: defaults.drop(1), throw: true))
+          return translation unless translation.nil?
+        end unless options[:message]
       else
         defaults = []
       end
@@ -496,15 +509,7 @@ def generate_message(attribute, type = :invalid, options = {})
 
       key = defaults.shift
       defaults = options.delete(:message) if options[:message]
-      value = (attribute != :base ? @base.send(:read_attribute_for_validation, attribute) : nil)
-
-      options = {
-        default: defaults,
-        model: @base.model_name.human,
-        attribute: @base.class.human_attribute_name(attribute),
-        value: value,
-        object: @base
-      }.merge!(options)
+      options[:default] = defaults
 
       I18n.translate(key, options)
     end

activerecord/test/cases/validations/i18n_generate_message_validation_test.rb

@@ -4,16 +4,20 @@
 require "models/topic"
 
 class I18nGenerateMessageValidationTest < ActiveRecord::TestCase
+  class Backend < I18n::Backend::Simple
+    include I18n::Backend::Fallbacks
+  end
+
   def setup
     Topic.clear_validators!
     @topic = Topic.new
-    I18n.backend = I18n::Backend::Simple.new
+    I18n.backend = Backend.new
   end
 
   def reset_i18n_load_path
     @old_load_path, @old_backend = I18n.load_path.dup, I18n.backend
     I18n.load_path.clear
-    I18n.backend = I18n::Backend::Simple.new
+    I18n.backend = Backend.new
     yield
   ensure
     I18n.load_path.replace @old_load_path
@@ -83,4 +87,16 @@ def test_generate_message_taken_with_custom_message
       assert_equal "Custom taken message", @topic.errors.generate_message(:title, :taken, value: "title")
     end
   end
+
+  test "activerecord attributes scope falls back to parent locale before it falls back to the :errors namespace" do
+    reset_i18n_load_path do
+      I18n.backend.store_translations "en", activerecord: { errors: { models: { topic: { attributes: { title: { taken: "custom en message" } } } } } }
+      I18n.backend.store_translations "en-US", errors: { messages: { taken: "generic en-US fallback" } }
+
+      I18n.with_locale "en-US" do
+        assert_equal "custom en message", @topic.errors.generate_message(:title, :taken, value: "title")
+        assert_equal "generic en-US fallback", @topic.errors.generate_message(:heading, :taken, value: "heading")
+      end
+    end
+  end
 end