Merge pull request #20831 from jmbejar/rails-api-json-error-response

Rails API: Ability to return error responses in json format also in development

6 files changed, 181 insertions, 38 deletions

diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index b8563d5076..271a57a7ad 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,3 +1,13 @@
+*   Add a `response_format` option to `ActionDispatch::DebugExceptions`
+    to configure the format of the response when errors occur in
+    development mode.
+
+    If `response_format` is `:default` the debug info will be rendered
+    in an HTML page. In the other hand, if the provided value is `:api`
+    the debug info will be rendered in the original response format.
+
+    *Jorge Bejar*
+
 *   Change the `protect_from_forgery` prepend default to `false`
 
     Per this comment
diff --git a/actionpack/lib/action_dispatch/http/mime_negotiation.rb b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
index 7acf91902d..0152c17ed4 100644
--- a/actionpack/lib/action_dispatch/http/mime_negotiation.rb
+++ b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
@@ -67,6 +67,8 @@ module ActionDispatch
 
           v = if params_readable
             Array(Mime[parameters[:format]])
+          elsif format = format_from_path_extension
+            Array(Mime[format])
           elsif use_accept_header && valid_accept_header
             accepts
           elsif xhr?
@@ -160,6 +162,13 @@ module ActionDispatch
       def use_accept_header
         !self.class.ignore_accept_header
       end
+
+      def format_from_path_extension
+        path = @env['action_dispatch.original_path'] || @env['PATH_INFO']
+        if match = path && path.match(/\.(\w+)\z/)
+          match.captures.first
+        end
+      end
     end
   end
 end
diff --git a/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
index 66bb74b9c5..b55c937e0c 100644
--- a/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
+++ b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
@@ -38,9 +38,10 @@ module ActionDispatch
       end
     end
 
-    def initialize(app, routes_app = nil)
-      @app        = app
-      @routes_app = routes_app
+    def initialize(app, routes_app = nil, response_format = :default)
+      @app             = app
+      @routes_app      = routes_app
+      @response_format = response_format
     end
 
     def call(env)
@@ -66,41 +67,79 @@ module ActionDispatch
       log_error(request, wrapper)
 
       if request.get_header('action_dispatch.show_detailed_exceptions')
-        traces = wrapper.traces
-
-        trace_to_show = 'Application Trace'
-        if traces[trace_to_show].empty? && wrapper.rescue_template != 'routing_error'
-          trace_to_show = 'Full Trace'
+        case @response_format
+        when :api
+          render_for_api_application(request, wrapper)
+        when :default
+          render_for_default_application(request, wrapper)
         end
+      else
+        raise exception
+      end
+    end
 
-        if source_to_show = traces[trace_to_show].first
-          source_to_show_id = source_to_show[:id]
-        end
+    def render_for_default_application(request, wrapper)
+      template = create_template(request, wrapper)
+      file = "rescues/#{wrapper.rescue_template}"
 
-        template = DebugView.new([RESCUES_TEMPLATE_PATH],
-          request: request,
-          exception: wrapper.exception,
-          traces: traces,
-          show_source_idx: source_to_show_id,
-          trace_to_show: trace_to_show,
-          routes_inspector: routes_inspector(exception),
-          source_extracts: wrapper.source_extracts,
-          line_number: wrapper.line_number,
-          file: wrapper.file
-        )
-        file = "rescues/#{wrapper.rescue_template}"
-
-        if request.xhr?
-          body = template.render(template: file, layout: false, formats: [:text])
-          format = "text/plain"
-        else
-          body = template.render(template: file, layout: 'rescues/layout')
-          format = "text/html"
-        end
-        render(wrapper.status_code, body, format)
+      if request.xhr?
+        body = template.render(template: file, layout: false, formats: [:text])
+        format = "text/plain"
       else
-        raise exception
+        body = template.render(template: file, layout: 'rescues/layout')
+        format = "text/html"
       end
+      render(wrapper.status_code, body, format)
+    end
+
+    def render_for_api_application(request, wrapper)
+      body = {
+        status: wrapper.status_code,
+        error:  Rack::Utils::HTTP_STATUS_CODES.fetch(
+          wrapper.status_code,
+          Rack::Utils::HTTP_STATUS_CODES[500]
+        ),
+        exception: wrapper.exception.inspect,
+        traces: wrapper.traces
+      }
+
+      content_type = request.formats.first
+      to_format = "to_#{content_type.to_sym}"
+
+      if content_type && body.respond_to?(to_format)
+        formatted_body = body.public_send(to_format)
+        format = content_type
+      else
+        formatted_body = body.to_json
+        format = Mime[:json]
+      end
+
+      render(wrapper.status_code, formatted_body, format)
+    end
+
+    def create_template(request, wrapper)
+      traces = wrapper.traces
+
+      trace_to_show = 'Application Trace'
+      if traces[trace_to_show].empty? && wrapper.rescue_template != 'routing_error'
+        trace_to_show = 'Full Trace'
+      end
+
+      if source_to_show = traces[trace_to_show].first
+        source_to_show_id = source_to_show[:id]
+      end
+
+      DebugView.new([RESCUES_TEMPLATE_PATH],
+        request: request,
+        exception: wrapper.exception,
+        traces: traces,
+        show_source_idx: source_to_show_id,
+        trace_to_show: trace_to_show,
+        routes_inspector: routes_inspector(wrapper.exception),
+        source_extracts: wrapper.source_extracts,
+        line_number: wrapper.line_number,
+        file: wrapper.file
+      )
     end
 
     def render(status, body, format)
diff --git a/actionpack/test/controller/mime/respond_to_test.rb b/actionpack/test/controller/mime/respond_to_test.rb
index c025c7fa00..76e2d3ff43 100644
--- a/actionpack/test/controller/mime/respond_to_test.rb
+++ b/actionpack/test/controller/mime/respond_to_test.rb
@@ -661,10 +661,6 @@ class RespondToControllerTest < ActionController::TestCase
   end
 
   def test_variant_inline_syntax
-    get :variant_inline_syntax, format: :js
-    assert_equal "text/javascript", @response.content_type
-    assert_equal "js", @response.body
-
     get :variant_inline_syntax
     assert_equal "text/html", @response.content_type
     assert_equal "none", @response.body
@@ -674,6 +670,12 @@ class RespondToControllerTest < ActionController::TestCase
     assert_equal "phone", @response.body
   end
 
+  def test_variant_inline_syntax_with_format
+    get :variant_inline_syntax, format: :js
+    assert_equal "text/javascript", @response.content_type
+    assert_equal "js", @response.body
+  end
+
   def test_variant_inline_syntax_without_block
     get :variant_inline_syntax_without_block, params: { v: :phone }
     assert_equal "text/html", @response.content_type
diff --git a/actionpack/test/dispatch/debug_exceptions_test.rb b/actionpack/test/dispatch/debug_exceptions_test.rb
index 30772bd9ed..159bf10545 100644
--- a/actionpack/test/dispatch/debug_exceptions_test.rb
+++ b/actionpack/test/dispatch/debug_exceptions_test.rb
@@ -75,6 +75,13 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
     end
   end
 
+  class BoomerAPI < Boomer
+    def call(env)
+      env['action_dispatch.show_detailed_exceptions'] = @detailed
+      raise "puke!"
+    end
+  end
+
   RoutesApp = Struct.new(:routes).new(SharedTestRoutes)
   ProductionApp  = ActionDispatch::DebugExceptions.new(Boomer.new(false), RoutesApp)
   DevelopmentApp = ActionDispatch::DebugExceptions.new(Boomer.new(true), RoutesApp)
@@ -205,6 +212,68 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
     assert_match(/ActionController::ParameterMissing/, body)
   end
 
+  test "rescue with json error for API request" do
+    @app = ActionDispatch::DebugExceptions.new(Boomer.new(true), RoutesApp, :api)
+
+    get "/", headers: { 'action_dispatch.show_exceptions' => true }
+    assert_response 500
+    assert_no_match(/<header>/, body)
+    assert_no_match(/<body>/, body)
+    assert_equal "application/json", response.content_type
+    assert_match(/RuntimeError: puke/, body)
+
+    get "/not_found", headers: { 'action_dispatch.show_exceptions' => true }
+    assert_response 404
+    assert_no_match(/<body>/, body)
+    assert_equal "application/json", response.content_type
+    assert_match(/#{AbstractController::ActionNotFound.name}/, body)
+
+    get "/method_not_allowed", headers: { 'action_dispatch.show_exceptions' => true }
+    assert_response 405
+    assert_no_match(/<body>/, body)
+    assert_equal "application/json", response.content_type
+    assert_match(/ActionController::MethodNotAllowed/, body)
+
+    get "/unknown_http_method", headers: { 'action_dispatch.show_exceptions' => true }
+    assert_response 405
+    assert_no_match(/<body>/, body)
+    assert_equal "application/json", response.content_type
+    assert_match(/ActionController::UnknownHttpMethod/, body)
+
+    get "/bad_request", headers: { 'action_dispatch.show_exceptions' => true }
+    assert_response 400
+    assert_no_match(/<body>/, body)
+    assert_equal "application/json", response.content_type
+    assert_match(/ActionController::BadRequest/, body)
+
+    get "/parameter_missing", headers: { 'action_dispatch.show_exceptions' => true }
+    assert_response 400
+    assert_no_match(/<body>/, body)
+    assert_equal "application/json", response.content_type
+    assert_match(/ActionController::ParameterMissing/, body)
+  end
+
+  test "rescue with json on API request returns only allowed formats or json as a fallback" do
+    @app = ActionDispatch::DebugExceptions.new(Boomer.new(true), RoutesApp, :api)
+
+    get "/index.json", headers: { 'action_dispatch.show_exceptions' => true }
+    assert_response 500
+    assert_equal "application/json", response.content_type
+    assert_match(/RuntimeError: puke/, body)
+
+    get "/index.html", headers: { 'action_dispatch.show_exceptions' => true }
+    assert_response 500
+    assert_no_match(/<header>/, body)
+    assert_no_match(/<body>/, body)
+    assert_equal "application/json", response.content_type
+    assert_match(/RuntimeError: puke/, body)
+
+    get "/index.xml", headers: { 'action_dispatch.show_exceptions' => true }
+    assert_response 500
+    assert_equal "application/xml", response.content_type
+    assert_match(/RuntimeError: puke/, body)
+  end
+
   test "does not show filtered parameters" do
     @app = DevelopmentApp
 
diff --git a/actionpack/test/dispatch/show_exceptions_test.rb b/actionpack/test/dispatch/show_exceptions_test.rb
index ffdf775836..14894d4b82 100644
--- a/actionpack/test/dispatch/show_exceptions_test.rb
+++ b/actionpack/test/dispatch/show_exceptions_test.rb
@@ -8,7 +8,7 @@ class ShowExceptionsTest < ActionDispatch::IntegrationTest
       case req.path
       when "/not_found"
         raise AbstractController::ActionNotFound
-      when "/bad_params"
+      when "/bad_params", "/bad_params.json"
         begin
           raise StandardError.new
         rescue
@@ -120,4 +120,18 @@ class ShowExceptionsTest < ActionDispatch::IntegrationTest
     assert_response 405
     assert_equal "", body
   end
+
+  test "bad params exception is returned in the correct format" do
+    @app = ProductionApp
+
+    get "/bad_params", headers: { 'action_dispatch.show_exceptions' => true }
+    assert_equal "text/html; charset=utf-8", response.headers["Content-Type"]
+    assert_response 400
+    assert_match(/400 error/, body)
+
+    get "/bad_params.json", headers: { 'action_dispatch.show_exceptions' => true }
+    assert_equal "application/json; charset=utf-8", response.headers["Content-Type"]
+    assert_response 400
+    assert_equal("{\"status\":400,\"error\":\"Bad Request\"}", body)
+  end
 end