Merge pull request ruby-i18n#482 from jeffjyang/add-i18n-exist-check-without-fallback

Add an option to disable fallbacks for the I18n.exists? check

Author: radar

lib/i18n.rb

@@ -223,11 +223,11 @@ def translate!(key, options = EMPTY_HASH)
     alias :t! :translate!
 
     # Returns true if a translation exists for a given key, otherwise returns false.
-    def exists?(key, _locale = nil, locale: _locale)
+    def exists?(key, _locale = nil, locale: _locale, **options)
       locale ||= config.locale
       raise Disabled.new('exists?') if locale == false
       raise I18n::ArgumentError if key.is_a?(String) && key.empty?
-      config.backend.exists?(locale, key)
+      config.backend.exists?(locale, key, options)
     end
 
     # Transliterates UTF-8 characters to ASCII. By default this method will

lib/i18n/backend/base.rb

@@ -64,7 +64,7 @@ def translate(locale, key, options = EMPTY_HASH)
         entry
       end
 
-      def exists?(locale, key)
+      def exists?(locale, key, options = EMPTY_HASH)
         lookup(locale, key) != nil
       end
 

lib/i18n/backend/chain.rb

@@ -73,9 +73,9 @@ def translate(locale, key, default_options = EMPTY_HASH)
           throw(:exception, I18n::MissingTranslation.new(locale, key, options))
         end
 
-        def exists?(locale, key)
+        def exists?(locale, key, options = EMPTY_HASH)
           backends.any? do |backend|
-            backend.exists?(locale, key)
+            backend.exists?(locale, key, options)
           end
         end
 

lib/i18n/backend/fallbacks.rb

@@ -68,7 +68,8 @@ def extract_non_symbol_default!(options)
         return first_non_symbol_default
       end
 
-      def exists?(locale, key)
+      def exists?(locale, key, options = EMPTY_HASH)
+        return super unless options.fetch(:fallback, true)
         I18n.fallbacks[locale].each do |fallback|
           begin
             return true if super(fallback, key)

test/backend/fallbacks_test.rb

@@ -158,6 +158,14 @@ def setup
     assert_equal 'FOO', I18n.t(:foo, :locale => :'de-DE')
   end
 
+  test "exists? falls back from de-DE to de given a key missing from the given locale" do
+    assert_equal true, I18n.exists?(:foo, :locale => :'de-DE')
+  end
+
+  test "exists? should return false when fallback disabled given a key missing from the given locale" do
+    assert_equal false, I18n.exists?(:foo, :locale => :'de-DE', fallback: false)
+  end
+
   test "falls back from de-DE to de when there is no translation for de-DE available when using arrays, too" do
     assert_equal ['FOO', 'FOO'], I18n.t([:foo, :foo], :locale => :'de-DE')
   end
@@ -212,4 +220,10 @@ def setup
     assert_equal false, I18n.exists?(:baz, :de)
     assert_equal false, I18n.exists?(:bogus, :'de-DE')
   end
+
+  test "exists? should return false when fallback is disabled given a key which is missing from the given locale" do
+    assert_equal true, I18n.exists?(:bar, :'de-DE')
+    assert_equal false, I18n.exists?(:bar, :'de-DE', fallback: false)
+    assert_equal false, I18n.exists?(:bar, :'de-DE-XX', fallback: false)
+  end
 end