Make error status for HTML/JS responses fully configurable

This essentially makes the previous change merged via #223 configurable,
so that we can keep the current behavior on existing apps, returning
`200 OK` even for errors, while changing the generator for new apps to
be configured with `422 Unprocessable Entity`, making them work better
with Hotwire/Turbo installations out of the box.

Please note that these defaults are likely to be swapped in a future
major version of Responders.

CHANGELOG.md

@@ -1,7 +1,7 @@
 ## Unreleased
 
 * Add config `responders.redirect_status` to allow overriding the redirect code/status used in redirects. The default is `302 Found`, which matches Rails, but it allows to change responders to redirect with `303 See Other` for example, to make it more compatible with how Hotwire/Turbo expects redirects to work.
-* Responding to an `HTML` or `JS` request that has errors on the resource now sets the status to `422 Unprocessable Entity`. (instead of the default of `200 OK`.) This makes it more consistent with other statuses more commonly used in APIs (JSON/XML for example), and works by default with Turbo/Hotwire which expects a 422 on form error HTML responses. Note that this change may break your application if you're relying on the previous 2xx status to handle error cases.
+* Add config `responders.error_status` to allow overriding the status code used to respond to `HTML` or `JS` requests that have errors on the resource. The default is `200 OK`, but it allows to change the response to be `422 Unprocessable Entity` in such cases for example, which makes it more consistent with other statuses more commonly used in APIs (like JSON/XML), and works by default with Turbo/Hotwire which expects a 422 on form error HTML responses. Note that changing this may break your application if you're relying on the previous 2xx status to handle error cases.
 * Add support for Ruby 3.0, 3.1, and 3.2, drop support for Ruby < 2.5.
 * Add support for Rails 6.1 and 7.0, drop support for Rails < 5.2.
 * Move CI to GitHub Actions.

README.md

@@ -213,7 +213,7 @@ def create
   @widget = Widget.new(widget_params)
   @widget.errors.add(:base, :invalid)
   # `respond_with` will render the `new` template again,
-  # and set the status to `422 Unprocessable Entity`.
+  # and set the status based on the configured `error_status`.
   respond_with @widget
 end
 ```
@@ -240,16 +240,29 @@ class WidgetsController < ApplicationController
 end
 ```
 
-## Configuring redirect statuses
+## Configuring error and redirect statuses
 
-By default, `respond_with` will perform redirects using the HTTP status code `302 Found`.
+By default, `respond_with` will respond to errors on `HTML` & `JS` requests using the HTTP status code `200 OK`,
+and perform redirects using the HTTP status code `302 Found`, both for backwards compatibility reasons.
 
-You can configure this behavior by setting `config.responders.redirect_status` to the desired status code.
+You can configure this behavior by setting `config.responders.error_status` and `config.responders.redirect_status` to the desired status codes.
 
 ```ruby
+config.responders.error_status = :unprocessable_entity
 config.responders.redirect_status = :see_other
 ```
 
+These can also be set in your custom `ApplicationResponder` if you have generated one: (see install instructions)
+
+```ruby
+class ApplicationResponder < ActionController::Responder
+  self.error_status = :unprocessable_entity
+  self.redirect_status = :see_other
+end
+```
+
+_Note: these defaults may change in a future major release of responders._
+
 ## Examples
 
 Want more examples ? Check out these blog posts:

lib/action_controller/respond_with.rb

@@ -96,7 +96,7 @@ def clear_respond_to
     #   2. If there are validation errors, the response
     #      renders a default action, which is <tt>:new</tt> for a
     #      +post+ request or <tt>:edit</tt> for +patch+ or +put+,
-    #      and the status is set to <tt>422 Unprocessable Entity</tt>.
+    #      and the status is set based on the configured `error_status`.
     #   Thus an example like this -
     #
     #     respond_to :html, :xml

lib/action_controller/responder.rb

@@ -120,6 +120,7 @@ module ActionController # :nodoc:
   #
   # Using <code>respond_with</code> with a block follows the same syntax as <code>respond_to</code>.
   class Responder
+    cattr_accessor :error_status, default: :ok
     cattr_accessor :redirect_status, default: :found
     attr_reader :controller, :request, :format, :resource, :resources, :options
 
@@ -238,7 +239,7 @@ def default_render
       if @default_response
         @default_response.call(options)
       elsif !get? && has_errors?
-        controller.render({ status: :unprocessable_entity }.merge!(options))
+        controller.render({ status: error_status }.merge!(options))
       else
         controller.render(options)
       end
@@ -266,6 +267,8 @@ def display(resource, given_options = {})
     end
 
     def display_errors
+      # TODO: use `error_status` once we switch the default to be `unprocessable_entity`,
+      # otherwise we'd be changing this behavior here now.
       controller.render format => resource_errors, :status => :unprocessable_entity
     end
 
@@ -307,7 +310,7 @@ def error_rendering_options
       if options[:render]
         options[:render]
       else
-        { action: default_action, status: :unprocessable_entity }
+        { action: default_action, status: error_status }
       end
     end
   end

lib/responders.rb

@@ -19,6 +19,7 @@ class Railtie < ::Rails::Railtie
     config.responders = ActiveSupport::OrderedOptions.new
     config.responders.flash_keys = [:notice, :alert]
     config.responders.namespace_lookup = false
+    config.responders.error_status = :ok
     config.responders.redirect_status = :found
 
     # Add load paths straight to I18n, so engines and application can overwrite it.
@@ -28,6 +29,7 @@ class Railtie < ::Rails::Railtie
     initializer "responders.flash_responder" do |app|
       Responders::FlashResponder.flash_keys = app.config.responders.flash_keys
       Responders::FlashResponder.namespace_lookup = app.config.responders.namespace_lookup
+      ActionController::Responder.error_status = app.config.responders.error_status
       ActionController::Responder.redirect_status = app.config.responders.redirect_status
     end
   end

test/action_controller/respond_with_test.rb

@@ -177,13 +177,25 @@ def test_using_resource_with_js_simply_tries_to_render_the_template
     assert_equal 200, @response.status
   end
 
-  def test_using_resource_for_post_with_js_renders_the_template_and_yields_unprocessable_entity_on_failure
+  def test_using_resource_for_post_with_js_renders_the_template_on_failure
     @request.accept = "text/javascript"
     errors = { name: :invalid }
     Customer.any_instance.stubs(:errors).returns(errors)
     post :using_resource
     assert_equal "text/javascript", @response.media_type
     assert_equal "alert(\"Hi\");", @response.body
+    assert_equal 200, @response.status
+  end
+
+  def test_using_resource_for_post_with_js_renders_the_template_and_yields_configured_error_status_on_failure
+    @request.accept = "text/javascript"
+    errors = { name: :invalid }
+    Customer.any_instance.stubs(:errors).returns(errors)
+    with_error_status(:unprocessable_entity) do
+      post :using_resource
+    end
+    assert_equal "text/javascript", @response.media_type
+    assert_equal "alert(\"Hi\");", @response.body
     assert_equal 422, @response.status
   end
 
@@ -270,12 +282,26 @@ def test_using_resource_for_post_with_html_redirects_on_success
     end
   end
 
-  def test_using_resource_for_post_with_html_rerender_and_yields_unprocessable_entity_on_failure
+  def test_using_resource_for_post_with_html_rerender_on_failure
     with_test_route_set do
       errors = { name: :invalid }
       Customer.any_instance.stubs(:errors).returns(errors)
       post :using_resource
       assert_equal "text/html", @response.media_type
+      assert_equal 200, @response.status
+      assert_equal "New world!\n", @response.body
+      assert_nil @response.location
+    end
+  end
+
+  def test_using_resource_for_post_with_html_rerender_and_yields_configured_error_status_on_failure
+    with_test_route_set do
+      errors = { name: :invalid }
+      Customer.any_instance.stubs(:errors).returns(errors)
+      with_error_status(:unprocessable_entity) do
+        post :using_resource
+      end
+      assert_equal "text/html", @response.media_type
       assert_equal 422, @response.status
       assert_equal "New world!\n", @response.body
       assert_nil @response.location
@@ -330,25 +356,54 @@ def test_using_resource_for_patch_with_html_redirects_on_success
     end
   end
 
-  def test_using_resource_for_patch_with_html_rerender_and_yields_unprocessable_entity_on_failure
+  def test_using_resource_for_patch_with_html_rerender_on_failure
     with_test_route_set do
       errors = { name: :invalid }
       Customer.any_instance.stubs(:errors).returns(errors)
       patch :using_resource
       assert_equal "text/html", @response.media_type
+      assert_equal 200, @response.status
+      assert_equal "Edit world!\n", @response.body
+      assert_nil @response.location
+    end
+  end
+
+  def test_using_resource_for_patch_with_html_rerender_and_yields_configured_status_on_failure
+    with_test_route_set do
+      errors = { name: :invalid }
+      Customer.any_instance.stubs(:errors).returns(errors)
+      with_error_status(:unprocessable_entity) do
+        patch :using_resource
+      end
+      assert_equal "text/html", @response.media_type
       assert_equal 422, @response.status
       assert_equal "Edit world!\n", @response.body
       assert_nil @response.location
     end
   end
 
-  def test_using_resource_for_patch_with_html_rerender_and_yields_unprocessable_entity_on_failure_even_on_method_override
+  def test_using_resource_for_patch_with_html_rerender_on_failure_even_on_method_override
     with_test_route_set do
       errors = { name: :invalid }
       Customer.any_instance.stubs(:errors).returns(errors)
       @request.env["rack.methodoverride.original_method"] = "POST"
       patch :using_resource
       assert_equal "text/html", @response.media_type
+      assert_equal 200, @response.status
+      assert_equal "Edit world!\n", @response.body
+      assert_nil @response.location
+    end
+  end
+
+  def test_using_resource_for_patch_with_html_rerender_and_yields_configured_error_status_on_failure_even_on_method_override
+    with_test_route_set do
+      errors = { name: :invalid }
+      Customer.any_instance.stubs(:errors).returns(errors)
+      @request.env["rack.methodoverride.original_method"] = "POST"
+      with_error_status(:unprocessable_entity) do
+        patch :using_resource
+      end
+      assert_equal "text/html", @response.media_type
       assert_equal 422, @response.status
       assert_equal "Edit world!\n", @response.body
       assert_nil @response.location
@@ -365,26 +420,54 @@ def test_using_resource_for_put_with_html_redirects_on_success
     end
   end
 
-  def test_using_resource_for_put_with_html_rerender_and_yields_unprocessable_entity_on_failure
+  def test_using_resource_for_put_with_html_rerender_on_failure
     with_test_route_set do
       errors = { name: :invalid }
       Customer.any_instance.stubs(:errors).returns(errors)
       put :using_resource
+      assert_equal "text/html", @response.media_type
+      assert_equal 200, @response.status
+      assert_equal "Edit world!\n", @response.body
+      assert_nil @response.location
+    end
+  end
 
+  def test_using_resource_for_put_with_html_rerender_and_yields_configured_error_status_on_failure
+    with_test_route_set do
+      errors = { name: :invalid }
+      Customer.any_instance.stubs(:errors).returns(errors)
+      with_error_status(:unprocessable_entity) do
+        put :using_resource
+      end
       assert_equal "text/html", @response.media_type
       assert_equal 422, @response.status
       assert_equal "Edit world!\n", @response.body
       assert_nil @response.location
     end
   end
 
-  def test_using_resource_for_put_with_html_rerender_and_yields_unprocessable_entity_on_failure_even_on_method_override
+  def test_using_resource_for_put_with_html_rerender_on_failure_even_on_method_override
     with_test_route_set do
       errors = { name: :invalid }
       Customer.any_instance.stubs(:errors).returns(errors)
       @request.env["rack.methodoverride.original_method"] = "POST"
       put :using_resource
       assert_equal "text/html", @response.media_type
+      assert_equal 200, @response.status
+      assert_equal "Edit world!\n", @response.body
+      assert_nil @response.location
+    end
+  end
+
+  def test_using_resource_for_put_with_html_rerender_and_yields_configured_error_status_on_failure_even_on_method_override
+    with_test_route_set do
+      errors = { name: :invalid }
+      Customer.any_instance.stubs(:errors).returns(errors)
+      @request.env["rack.methodoverride.original_method"] = "POST"
+      with_error_status(:unprocessable_entity) do
+        put :using_resource
+      end
+      assert_equal "text/html", @response.media_type
       assert_equal 422, @response.status
       assert_equal "Edit world!\n", @response.body
       assert_nil @response.location
@@ -688,6 +771,14 @@ def with_test_route_set
     end
   end
 
+  def with_error_status(status)
+    old_status = ActionController::Responder.error_status
+    ActionController::Responder.error_status = status
+    yield
+  ensure
+    ActionController::Responder.error_status = old_status
+  end
+
   def with_redirect_status(status)
     old_status = ActionController::Responder.redirect_status
     ActionController::Responder.redirect_status = status