From 783ba47ecf08bd3f9c7c7454ea0ba75973384adc Mon Sep 17 00:00:00 2001
From: Edward Wible <aewible@gmail.com>
Date: Sat, 20 Jul 2013 20:16:20 -0300
Subject: [PATCH 1/2] Set :en as fallback locale for grape errors when
 translations are missing for the default locale

---
 README.md                             |  6 +++++
 lib/grape/exceptions/base.rb          |  4 ++-
 spec/grape/validations/coerce_spec.rb | 38 ++++++++++++++++++++-------
 3 files changed, 37 insertions(+), 11 deletions(-)

diff --git a/README.md b/README.md
index 63419aa94..f8941fccb 100644
--- a/README.md
+++ b/README.md
@@ -430,6 +430,12 @@ rescue_from Grape::Exceptions::Validation do |e|
 end
 ```
 
+### I18n
+
+Grape supports I18n for parameter-related error messages, but will fallback to English if 
+translations for the default locale have not been provided. See [en.yml](https://github.com/intridea/grape/blob/master/lib/grape/locale/en.yml) for message keys.
+
+
 ## Headers
 
 Request headers are available through the `headers` helper or from `env` in their original form.
diff --git a/lib/grape/exceptions/base.rb b/lib/grape/exceptions/base.rb
index a917fa65f..71363d327 100644
--- a/lib/grape/exceptions/base.rb
+++ b/lib/grape/exceptions/base.rb
@@ -4,6 +4,7 @@ class Base < StandardError
 
       BASE_MESSAGES_KEY = 'grape.errors.messages'
       BASE_ATTRIBUTES_KEY = 'grape.errors.attributes'
+      FALLBACK_LOCALE = :en
 
       attr_reader :status, :message, :headers
 
@@ -58,7 +59,8 @@ def translate_message(key, options = {})
       end
 
       def translate(key, options = {})
-        ::I18n.translate(key, options)
+        message = ::I18n.translate(key, options)
+        message.present? ? message : ::I18n.translate(key, options.merge({:locale => FALLBACK_LOCALE}))
       end
 
     end
diff --git a/spec/grape/validations/coerce_spec.rb b/spec/grape/validations/coerce_spec.rb
index 47eb3c563..1d056e893 100644
--- a/spec/grape/validations/coerce_spec.rb
+++ b/spec/grape/validations/coerce_spec.rb
@@ -6,19 +6,37 @@
   def app; subject end
 
   describe 'coerce' do
-    it "i18n error on malformed input" do
-      I18n.load_path << File.expand_path('../zh-CN.yml',__FILE__)
-      I18n.reload!
-      I18n.locale = :'zh-CN'
-      subject.params { requires :age, :type => Integer }
-      subject.get '/single' do 'int works'; end
+    
+    context "i18n" do
+    
+      after :each do
+        I18n.locale = :en
+      end
+    
+      it "i18n error on malformed input" do
+        I18n.load_path << File.expand_path('../zh-CN.yml',__FILE__)
+        I18n.reload!
+        I18n.locale = :'zh-CN'
+        subject.params { requires :age, :type => Integer }
+        subject.get '/single' do 'int works'; end
+
+        get '/single', :age => '43a'
+        last_response.status.should == 400
+        last_response.body.should == '年龄格式不正确'
+      end
+    
+      it 'gives an english fallback error when default locale message is blank' do
+        I18n.locale = :'pt-BR'
+        subject.params { requires :age, :type => Integer }
+        subject.get '/single' do 'int works'; end
 
-      get '/single', :age => '43a'
-      last_response.status.should == 400
-      last_response.body.should == '年龄格式不正确'
-      I18n.locale = :en
+        get '/single', :age => '43a'
+        last_response.status.should == 400
+        last_response.body.should == 'invalid parameter: age'
+      end
 
     end
+    
     it 'error on malformed input' do
       subject.params { requires :int, :type => Integer }
       subject.get '/single' do 'int works'; end

From b8088f2dda2955e56535f93539dd94cd8acf8888 Mon Sep 17 00:00:00 2001
From: Edward Wible <aewible@gmail.com>
Date: Mon, 22 Jul 2013 03:37:42 -0300
Subject: [PATCH 2/2] update readme and changelog

---
 CHANGELOG.md | 1 +
 README.md    | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 019dd335f..271e334a0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@ Next Release
 * Grape is no longer tested against Ruby 1.8.7.
 * [#442](https://github.com/intridea/grape/issues/442): Enable incrementally building on top of a previous API version - [@dblock](https://github.com/dblock).
 * [#442](https://github.com/intridea/grape/issues/442): API `version` can now take an array of multiple versions - [@dblock](https://github.com/dblock).
+* [#444](https://github.com/intridea/grape/issues/444): Added :en as fallback locale for I18n - [@aew](https://github.com/aew).
 
 * Your contribution here.
 
diff --git a/README.md b/README.md
index f8941fccb..0b374e676 100644
--- a/README.md
+++ b/README.md
@@ -433,7 +433,7 @@ end
 ### I18n
 
 Grape supports I18n for parameter-related error messages, but will fallback to English if 
-translations for the default locale have not been provided. See [en.yml](https://github.com/intridea/grape/blob/master/lib/grape/locale/en.yml) for message keys.
+translations for the default locale have not been provided. See [en.yml](lib/grape/locale/en.yml) for message keys.
 
 
 ## Headers