fix(#1922): Allow to use instance variables defined in the endpoints inside rescue_from

CHANGELOG.md

@@ -3,6 +3,7 @@
 #### Features
 
 * [#2371](https://github.com/ruby-grape/grape/pull/2371): Use a param value as the `default` value of other param - [@jcagarcia](https://github.com/jcagarcia).
+* [#2377](https://github.com/ruby-grape/grape/pull/2377): Allow to use instance variables values inside rescue_from - [@jcagarcia](https://github.com/jcagarcia).
 * Your contribution here.
 
 #### Fixes

lib/grape/dsl/inside_route.rb

@@ -167,6 +167,23 @@ def error!(message, status = nil, additional_headers = nil)
         throw :error, message: message, status: self.status, headers: headers
       end
 
+      # Creates a Rack response based on the provided message, status, and headers.
+      # The content type in the headers is set to the default content type unless provided.
+      # The message is HTML-escaped if the content type is 'text/html'.
+      #
+      # @param message [String] The content of the response.
+      # @param status [Integer] The HTTP status code.
+      # @params headers [Hash] (optional) Headers for the response
+      #                      (default: {Rack::CONTENT_TYPE => content_type}).
+      #
+      # Returns:
+      # A Rack::Response object containing the specified message, status, and headers.
+      #
+      def rack_response(message, status = 200, headers = { Rack::CONTENT_TYPE => content_type })
+        message = ERB::Util.html_escape(message) if headers[Rack::CONTENT_TYPE] == 'text/html'
+        Rack::Response.new([message], Rack::Utils.status_code(status), headers)
+      end
+
       # Redirect to a new url.
       #
       # @param url [String] The url to be redirect.

lib/grape/middleware/error.rb

@@ -46,7 +46,7 @@ def call!(env)
             rescue_handler_for_any_class(e.class) ||
             raise
 
-          run_rescue_handler(handler, e)
+          run_rescue_handler(@env[Grape::Env::API_ENDPOINT], handler, e)
         end
       end
 
@@ -119,21 +119,29 @@ def rescue_handler_for_any_class(klass)
         options[:all_rescue_handler] || :default_rescue_handler
       end
 
-      def run_rescue_handler(handler, error)
+      def run_rescue_handler(endpoint, handler, error)
         if handler.instance_of?(Symbol)
           raise NoMethodError, "undefined method '#{handler}'" unless respond_to?(handler)
 
           handler = public_method(handler)
         end
 
-        response = handler.arity.zero? ? instance_exec(&handler) : instance_exec(error, &handler)
+        response = (catch(:error) do
+          handler.arity.zero? ? endpoint.instance_exec(&handler) : endpoint.instance_exec(error, &handler)
+        end)
+
+        response = error!(response[:message], response[:status], response[:headers]) if error?(response)
 
         if response.is_a?(Rack::Response)
           response
         else
-          run_rescue_handler(:default_rescue_handler, Grape::Exceptions::InvalidResponse.new)
+          run_rescue_handler(endpoint, :default_rescue_handler, Grape::Exceptions::InvalidResponse.new)
         end
       end
+
+      def error?(response)
+        response.is_a?(Hash) && response[:message] && response[:status] && response[:headers]
+      end
     end
   end
 end

spec/grape/api_spec.rb

@@ -2130,6 +2130,25 @@ class CustomError < Grape::Exceptions::Base; end
       expect(last_response.status).to be 500
       expect(last_response.body).to eql 'Invalid response'
     end
+
+    context 'when using instance variables inside the rescue_from' do
+      it 'is able to access the values' do
+        expected_instance_variable_value = 'wadus'
+
+        subject.rescue_from(:all) do
+          body = { my_var: @my_var }
+          error!(body, 400)
+        end
+        subject.get('/') do
+          @my_var = expected_instance_variable_value
+          raise
+        end
+
+        get '/'
+        expect(last_response.status).to be 400
+        expect(last_response.body).to eq({ my_var: expected_instance_variable_value }.to_json)
+      end
+    end
   end
 
   describe '.rescue_from klass, block' do