Store message_key on validation exception

CHANGELOG.md

@@ -3,6 +3,7 @@
 
 * [#1216](https://github.com/ruby-grape/grape/pull/1142): Fix JSON error response when calling `error!` with non-Strings - [@jrforrest](https://github.com/jrforrest).
 * [#1225](https://github.com/ruby-grape/grape/pull/1225): Fix `given` with nested params not returning correct declared params - [@JanStevens](https://github.com/JanStevens).
+* [#1227](https://github.com/ruby-grape/grape/pull/1227): Store `message_key` on Grape::Exceptions::Validation - [@stjhimy](https://github.com/sthimy).
 * Your contribution here.
 
 0.14.0 (12/07/2015)

lib/grape/exceptions/validation.rb

@@ -4,10 +4,12 @@ module Grape
   module Exceptions
     class Validation < Grape::Exceptions::Base
       attr_accessor :params
+      attr_accessor :message_key
 
       def initialize(args = {})
         fail 'Params are missing:' unless args.key? :params
         @params = args[:params]
+        @message_key = args[:message_key]
         args[:message] = translate_message(args[:message_key]) if args.key? :message_key
         super
       end

spec/grape/exceptions/validation_spec.rb

@@ -0,0 +1,11 @@
+require 'spec_helper'
+
+describe Grape::Exceptions::Validation do
+  it 'fails when params are missing' do
+    expect { Grape::Exceptions::Validation.new(message_key: 'presence') }.to raise_error(RuntimeError, 'Params are missing:')
+  end
+
+  it 'store message_key' do
+    expect(Grape::Exceptions::Validation.new(params: ['id'], message_key: 'presence').message_key).to eq('presence')
+  end
+end