adding option to allow grape to handle Grape::Exception when rescue :…

…all is set

CHANGELOG.md

@@ -1,7 +1,7 @@
 0.16.3 (Next)
 =============
 
-* Your contribution here.
+* [#1398](https://github.com/ruby-grape/grape/pull/1398): Option to allow Grape to handle Grape::Exception when rescue :all is set [@mmclead](https://github.com/mmclead)
 
 #### Features
 

README.md

@@ -1806,6 +1806,14 @@ class Twitter::API < Grape::API
 end
 ```
 
+As an option to ```rescue_from :all``` you can specify that Grape should still use its built in exception handling.
+
+```ruby
+class Twitter::API < Grape::API
+  rescue_from :all, rescue_grape_errors: true
+end
+```
+
 You can also rescue specific exceptions.
 
 ```ruby

lib/grape/middleware/error.rb

@@ -12,7 +12,7 @@ def default_options
           error_formatters: {},
           rescue_all: false, # true to rescue all exceptions
           rescue_subclasses: true, # rescue subclasses of exceptions listed
-          rescue_options: { backtrace: false }, # true to display backtrace
+          rescue_options: { backtrace: false, rescue_grape_errors: false }, # true to display backtrace, true to let Grape handle Grape::Exceptions
           rescue_handlers: {}, # rescue handler blocks
           base_only_rescue_handlers: {}, # rescue handler blocks rescuing only the base class
           all_rescue_handler: nil # rescue handler block to rescue from all exceptions
@@ -30,7 +30,7 @@ def call!(env)
           end)
         rescue StandardError => e
           is_rescuable = rescuable?(e.class)
-          if e.is_a?(Grape::Exceptions::Base) && !is_rescuable
+          if e.is_a?(Grape::Exceptions::Base) && (!is_rescuable || rescuable_by_grape?(e.class))
             handler = ->(arg) { error_response(arg) }
           else
             raise unless is_rescuable
@@ -59,6 +59,11 @@ def rescuable?(klass)
         options[:rescue_all] || (options[:rescue_handlers] || []).any? { |error, _handler| klass <= error } || (options[:base_only_rescue_handlers] || []).include?(klass)
       end
 
+      def rescuable_by_grape?(klass)
+        return false if klass == Grape::Exceptions::InvalidVersionHeader
+        options[:rescue_options][:rescue_grape_errors]
+      end
+
       def exec_handler(e, &handler)
         if handler.lambda? && handler.arity == 0
           instance_exec(&handler)

spec/grape/exceptions/body_parse_errors_spec.rb

@@ -50,6 +50,28 @@ def app
         expect(last_response.body).to eq('message was processed')
       end
     end
+
+    context 'and rescue_grape_errors set to true' do
+      before do
+        subject.rescue_from :all, rescue_grape_errors: true
+      end
+
+      context 'with content_type json' do
+        it 'returns body parsing error message' do
+          post '/beer', 'test', 'CONTENT_TYPE' => 'application/json'
+          expect(last_response.status).to eq 400
+          expect(last_response.body).to include 'message body does not match declared format'
+        end
+      end
+
+      context 'with content_type xml' do
+        it 'returns body parsing error message' do
+          post '/beer', 'test', 'CONTENT_TYPE' => 'application/xml'
+          expect(last_response.status).to eq 400
+          expect(last_response.body).to include 'message body does not match declared format'
+        end
+      end
+    end
   end
 
   context 'api without a rescue handler' do