Display exceptions in text format for xhr request

actionpack/CHANGELOG.md

+*   Development mode exceptions are rendered in text format in case of XHR request.
+
+    *Kir Shatrov*
+
 *   Fix an issue where :if and :unless controller action procs were being run
     before checking for the correct action in the :only and :unless options.
 

actionpack/lib/action_dispatch/middleware/debug_exceptions.rb

@@ -34,27 +34,35 @@ def render_exception(env, exception)
       log_error(env, wrapper)
 
       if env['action_dispatch.show_detailed_exceptions']
+        request = Request.new(env)
         template = ActionView::Base.new([RESCUES_TEMPLATE_PATH],
-          :request => Request.new(env),
-          :exception => wrapper.exception,
-          :application_trace => wrapper.application_trace,
-          :framework_trace => wrapper.framework_trace,
-          :full_trace => wrapper.full_trace,
-          :routes_inspector => routes_inspector(exception),
-          :source_extract => wrapper.source_extract,
-          :line_number => wrapper.line_number,
-          :file => wrapper.file
+          request: request,
+          exception: wrapper.exception,
+          application_trace: wrapper.application_trace,
+          framework_trace: wrapper.framework_trace,
+          full_trace: wrapper.full_trace,
+          routes_inspector: routes_inspector(exception),
+          source_extract: wrapper.source_extract,
+          line_number: wrapper.line_number,
+          file: wrapper.file
         )
         file = "rescues/#{wrapper.rescue_template}"
-        body = template.render(:template => file, :layout => 'rescues/layout')
-        render(wrapper.status_code, body)
+
+        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)
       else
         raise exception
       end
     end
 
-    def render(status, body)
-      [status, {'Content-Type' => "text/html; charset=#{Response.default_charset}", 'Content-Length' => body.bytesize.to_s}, [body]]
+    def render(status, body, format)
+      [status, {'Content-Type' => "#{format}; charset=#{Response.default_charset}", 'Content-Length' => body.bytesize.to_s}, [body]]
     end
 
     def log_error(env, wrapper)

actionpack/lib/action_dispatch/middleware/templates/rescues/_request_and_response.text.erb

+<%
+  clean_params = @request.filtered_parameters.clone
+  clean_params.delete("action")
+  clean_params.delete("controller")
+
+  request_dump = clean_params.empty? ? 'None' : clean_params.inspect.gsub(',', ",\n")
+
+  def debug_hash(object)
+    object.to_hash.sort_by { |k, _| k.to_s }.map { |k, v| "#{k}: #{v.inspect rescue $!.message}" }.join("\n")
+  end unless self.class.method_defined?(:debug_hash)
+%>
+
+Request parameters
+<%= request_dump %>
+
+Session dump
+<%= debug_hash @request.session %>
+
+Env dump
+<%= debug_hash @request.env.slice(*@request.class::ENV_METHODS) %>
+
+Response headers
+<%= defined?(@response) ? @response.headers.inspect.gsub(',', ",\n") : 'None' %>

actionpack/lib/action_dispatch/middleware/templates/rescues/_trace.text.erb

+<%
+  traces = { "Application Trace" => @application_trace,
+             "Framework Trace"   => @framework_trace,
+             "Full Trace"        => @full_trace }
+%>
+
+Rails.root: <%= defined?(Rails) && Rails.respond_to?(:root) ? Rails.root : "unset" %>
+
+<% traces.each do |name, trace| %>
+<% if trace.any? %>
+<%= name %>
+<%= trace.join("\n") %>
+
+<% end %>
+<% end %>

actionpack/lib/action_dispatch/middleware/templates/rescues/missing_template.text.erb

+Template is missing
+
+<%= @exception.message %>

actionpack/lib/action_dispatch/middleware/templates/rescues/routing_error.text.erb

+Routing Error
+
+<%= @exception.message %>
+<% unless @exception.failures.empty? %>
+Failure reasons:
+<% @exception.failures.each do |route, reason| %>
+  - <%= route.inspect.delete('\\') %></code> failed because <%= reason.downcase %>
+<% end %>
+<% end %>
+
+<%= render template: "rescues/_trace", format: :text %>

actionpack/lib/action_dispatch/middleware/templates/rescues/template_error.text.erb

+<% @source_extract = @exception.source_extract(0, :html) %>
+<%= @exception.original_exception.class.to_s %> in <%= @request.parameters["controller"].camelize if @request.parameters["controller"] %>#<%= @request.parameters["action"] %>
+
+Showing <%= @exception.file_name %> where line #<%= @exception.line_number %> raised:
+<%= @exception.message %>
+<%= @exception.sub_template_message %>
+<%= render template: "rescues/_trace", format: :text %>
+<%= render template: "rescues/_request_and_response", format: :text %>

actionpack/lib/action_dispatch/middleware/templates/rescues/unknown_action.text.erb

+Unknown action
+
+<%= @exception.message %>

actionpack/test/dispatch/debug_exceptions_test.rb

@@ -128,6 +128,47 @@ def setup
     assert_match(/ActionController::ParameterMissing/, body)
   end
 
+  test "rescue with text error for xhr request" do
+    @app = DevelopmentApp
+    xhr_request_env = {'action_dispatch.show_exceptions' => true, 'HTTP_X_REQUESTED_WITH' => 'XMLHttpRequest'}
+
+    get "/", {}, xhr_request_env
+    assert_response 500
+    assert_no_match(/<body>/, body)
+    assert_equal response.content_type, "text/plain"
+    assert_match(/puke/, body)
+
+    get "/not_found", {}, xhr_request_env
+    assert_response 404
+    assert_no_match(/<body>/, body)
+    assert_equal response.content_type, "text/plain"
+    assert_match(/#{AbstractController::ActionNotFound.name}/, body)
+
+    get "/method_not_allowed", {}, xhr_request_env
+    assert_response 405
+    assert_no_match(/<body>/, body)
+    assert_equal response.content_type, "text/plain"
+    assert_match(/ActionController::MethodNotAllowed/, body)
+
+    get "/unknown_http_method", {}, xhr_request_env
+    assert_response 405
+    assert_no_match(/<body>/, body)
+    assert_equal response.content_type, "text/plain"
+    assert_match(/ActionController::UnknownHttpMethod/, body)
+
+    get "/bad_request", {}, xhr_request_env
+    assert_response 400
+    assert_no_match(/<body>/, body)
+    assert_equal response.content_type, "text/plain"
+    assert_match(/ActionController::BadRequest/, body)
+
+    get "/parameter_missing", {}, xhr_request_env
+    assert_response 400
+    assert_no_match(/<body>/, body)
+    assert_equal response.content_type, "text/plain"
+    assert_match(/ActionController::ParameterMissing/, body)
+  end
+
   test "does not show filtered parameters" do
     @app = DevelopmentApp