Fix JSON error response when calling error! with non-Strings.

Author: jrforrest

CHANGELOG.md

@@ -1,6 +1,7 @@
 0.14.1 (Next)
 =============
 
+* [#1216](https://github.com/ruby-grape/grape/pull/1142): Fix JSON error response when calling `error!` with non-Strings - [@jrforrest](https://github.com/jrforrest).
 * Your contribution here.
 
 0.14.0 (12/17/2015)

README.md

@@ -1543,6 +1543,12 @@ You can abort the execution of an API method by raising errors with `error!`.
 error! 'Access Denied', 401
 ```
 
+Anything that responds to `#to_s` can be given as a first argument to `error!`.
+
+```ruby
+error! :not_found, 404
+```
+
 You can also return JSON formatted objects by raising error! and passing a hash
 instead of a message.
 

lib/grape/error_formatter/json.rb

@@ -3,14 +3,23 @@ module ErrorFormatter
     module Json
       class << self
         def call(message, backtrace, options = {}, env = nil)
-          message = Grape::ErrorFormatter::Base.present(message, env)
+          result = wrap_message(Grape::ErrorFormatter::Base.present(message, env))
 
-          result = message.is_a?(String) ? { error: message } : message
           if (options[:rescue_options] || {})[:backtrace] && backtrace && !backtrace.empty?
             result = result.merge(backtrace: backtrace)
           end
           MultiJson.dump(result)
         end
+
+        private
+
+        def wrap_message(message)
+          if message.is_a?(Exceptions::ValidationErrors) || message.is_a?(Hash)
+            message
+          else
+            { error: message }
+          end
+        end
       end
     end
   end

spec/grape/api_spec.rb

@@ -1668,13 +1668,23 @@ def self.call(message, _backtrace, _option, _env)
       get '/error'
       expect(last_response.body).to eql 'Access Denied'
     end
-    it 'rescues error! and return json' do
-      subject.format :json
-      subject.get '/error' do
-        error!('Access Denied', 401)
+    context 'with json format' do
+      before { subject.format :json }
+
+      it 'rescues error! called with a string and returns json' do
+        subject.get('/error') { error!(:failure, 401) }
+      end
+      it 'rescues error! called with a symbol and returns json' do
+        subject.get('/error') { error!(:failure, 401) }
+      end
+      it 'rescues error! called with a hash and returns json' do
+        subject.get('/error') { error!({ error: :failure }, 401) }
+      end
+
+      after do
+        get '/error'
+        expect(last_response.body).to eql('{"error":"failure"}')
       end
-      get '/error'
-      expect(last_response.body).to eql '{"error":"Access Denied"}'
     end
   end