Commit flash changes when using a redirect route.

In ca324a0d the flash middleware was effectively removed by its constructor returning the app it was passed and the `commit_flash` call was moved to the `ActionController::Metal#dispatch` method. This broke any redirect routes that modified the flash because the redirect happens before `dispatch` gets called. To fix it, this commit adds a `commit_flash` call in the `serve` method of `ActionDispatch::Routing::Redirect`. Fixes #27992.

Commit flash changes when using a redirect route.
In ca324a0d the flash middleware was effectively removed by its constructor returning the app it was passed and the `commit_flash` call was moved to the `ActionController::Metal#dispatch` method. This broke any redirect routes that modified the flash because the redirect happens before `dispatch` gets called. To fix it, this commit adds a `commit_flash` call in the `serve` method of `ActionDispatch::Routing::Redirect`. Fixes #27992.
558336ee · Andrew White · b04473e5 · 558336ee · 558336ee · 558336ee
3 changed file
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
+*   Commit flash changes when using a redirect route.
+
+    Fixes #27992.
+
+    *Andrew White*
+
+
 ## Rails 5.1.0.beta1 (February 23, 2017) ##

 *   Prefer `remove_method` over `undef_method` when reloading routes

--- a/actionpack/lib/action_dispatch/routing/redirection.rb
+++ b/actionpack/lib/action_dispatch/routing/redirection.rb
@@ -36,6 +36,8 @@ def serve(req)
        uri.host   ||= req.host
        uri.port   ||= req.port unless req.standard_port?

+        req.commit_flash
+
        body = %(<html><body>You are being <a href="#{ERB::Util.unwrapped_html_escape(uri.to_s)}">redirected</a>.</body></html>)

        headers = {

--- a/actionpack/test/dispatch/routing_test.rb
+++ b/actionpack/test/dispatch/routing_test.rb
@@ -4913,3 +4913,52 @@ def test_paths_with_partial_dynamic_segments_are_recognised
    )
  end
 end
+
+class FlashRedirectTest < ActionDispatch::IntegrationTest
+  SessionKey = "_myapp_session"
+  Generator  = ActiveSupport::LegacyKeyGenerator.new("b3c631c314c0bbca50c1b2843150fe33")
+
+  class KeyGeneratorMiddleware
+    def initialize(app)
+      @app = app
+    end
+
+    def call(env)
+      env["action_dispatch.key_generator"] ||= Generator
+      @app.call(env)
+    end
+  end
+
+  class FooController < ActionController::Base
+    def bar
+      render plain: (flash[:foo] || "foo")
+    end
+  end
+
+  Routes = ActionDispatch::Routing::RouteSet.new
+  Routes.draw do
+    get "/foo", to: redirect { |params, req| req.flash[:foo] = "bar"; "/bar" }
+    get "/bar", to: "flash_redirect_test/foo#bar"
+  end
+
+  APP = build_app Routes do |middleware|
+    middleware.use KeyGeneratorMiddleware
+    middleware.use ActionDispatch::Session::CookieStore, key: SessionKey
+    middleware.use ActionDispatch::Flash
+    middleware.delete ActionDispatch::ShowExceptions
+  end
+
+  def app
+    APP
+  end
+
+  include Routes.url_helpers
+
+  def test_block_redirect_commits_flash
+    get "/foo", env: { "action_dispatch.key_generator" => Generator }
+    assert_response :redirect
+
+    follow_redirect!
+    assert_equal "bar", response.body
+  end
+end