feat(RenderMiddleware) use middleware for view helper lifecycle

Author: rmosolgo

lib/react/rails.rb

@@ -1,6 +1,7 @@
 require 'react/rails/asset_variant'
 require 'react/rails/engine'
 require 'react/rails/railtie'
+require 'react/rails/render_middleware'
 require 'react/rails/version'
 require 'react/rails/component_mount'
 require 'react/rails/view_helper'

lib/react/rails/railtie.rb

@@ -4,7 +4,6 @@ module React
   module Rails
     class Railtie < ::Rails::Railtie
       config.react = ActiveSupport::OrderedOptions.new
-
       # Sensible defaults. Can be overridden in application.rb
       config.react.variant = (::Rails.env.production? ? :production : :development)
       config.react.addons = false
@@ -25,6 +24,7 @@ class Railtie < ::Rails::Railtie
 
       # Include the react-rails view helper lazily
       initializer "react_rails.setup_view_helpers", group: :all do |app|
+        app.config.middleware.use(::React::Rails::RenderMiddleware)
         app.config.react.jsx_transformer_class ||= React::JSX::DEFAULT_TRANSFORMER
         React::JSX.transformer_class = app.config.react.jsx_transformer_class
         React::JSX.transform_options = app.config.react.jsx_transform_options

lib/react/rails/render_middleware.rb

@@ -0,0 +1,16 @@
+module React
+  module Rails
+    class RenderMiddleware
+      HELPER_IMPLEMENTATION_KEY = "react_rails.view_helper_implementation"
+      def initialize(app)
+        @app = app
+      end
+
+      def call(env)
+        new_helper = React::Rails::ViewHelper.helper_implementation_class.new
+        env[HELPER_IMPLEMENTATION_KEY] = new_helper
+        @app.call(env)
+      end
+    end
+  end
+end

lib/react/rails/view_helper.rb

@@ -7,7 +7,9 @@ module ViewHelper
       mattr_accessor :helper_implementation_class
 
       def react_component(*args, &block)
-        self.helper_implementation_class.new.react_component(*args, &block)
+        impl_key = React::Rails::RenderMiddleware::HELPER_IMPLEMENTATION_KEY
+        helper_obj = request.env[impl_key]
+        helper_obj.react_component(*args, &block)
       end
     end
   end

test/react/rails/render_middleware_test.rb

@@ -0,0 +1,42 @@
+require 'test_helper'
+
+# This helper implementation just counts the number of
+# calls to `react_component`
+class DummyHelperImplementation
+  attr_reader :counter
+  def initialize
+    @counter = 0
+  end
+
+  def react_component(*args)
+    @counter += 1
+  end
+end
+
+class RenderMiddlewareTest < ActionDispatch::IntegrationTest
+  impl_key = React::Rails::RenderMiddleware::HELPER_IMPLEMENTATION_KEY
+
+  def setup
+    @previous_helper_implementation = React::Rails::ViewHelper.helper_implementation_class
+    React::Rails::ViewHelper.helper_implementation_class = DummyHelperImplementation
+  end
+
+  def teardown
+    React::Rails::ViewHelper.helper_implementation_class = @previous_helper_implementation
+  end
+
+  test "it creates a helper object and puts it in the request env" do
+    get '/pages/1'
+    helper_obj = request.env[impl_key]
+    assert(helper_obj.is_a?(DummyHelperImplementation), "It uses the view helper implementation class")
+    assert_equal(1, helper_obj.counter, "It uses that object during rendering")
+  end
+
+  test "there's a new helper object for every request" do
+    get '/pages/1'
+    first_helper = request.env[impl_key]
+    get '/pages/1'
+    second_helper = request.env[impl_key]
+    assert(first_helper != second_helper, "The helper for the second request is brand new")
+  end
+end