Don't convert empty body on POST/PUT.

When posting with content type 'application/json' and an empty body, multi_json crashes on the empty string.

Author: tim-vandecasteele

lib/grape/endpoint.rb

@@ -125,7 +125,7 @@ def params
 
     # Pull out request body params if the content type matches and we're on a POST or PUT
     def body_params
-      if ['POST', 'PUT'].include?(request.request_method.to_s.upcase)
+      if ['POST', 'PUT'].include?(request.request_method.to_s.upcase) && request.body.size > 0
         return case env['CONTENT_TYPE']
           when 'application/json'
             MultiJson.decode(request.body.read)

spec/grape/endpoint_spec.rb

@@ -191,6 +191,11 @@ def app; subject end
         last_response.body.should == 'Bobby T.'
       end
 
+      it 'should not convert empty JSON bodies to params' do
+        put '/request_body', '', {'CONTENT_TYPE' => 'application/json'}
+        last_response.body.should == ''
+      end
+
       it 'should convert XML bodies to params' do
         post '/request_body', '<user>Bobby T.</user>', {'CONTENT_TYPE' => 'application/xml'}
         last_response.body.should == 'Bobby T.'