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A set of responders modules to dry up your Rails app.


Add the responders gem to your Gemfile:

gem "responders"

Update your bundle and run the install generator:

$ bundle install
$ rails g responders:install

If you are including this gem to support backwards compatibilty for responders in previous releases of Rails, you only need to include the gem and bundle.

$ bundle install

Responders Types


Sets the flash based on the controller action and resource status. For instance, if you do: respond_with(@post) on a POST request and the resource @post does not contain errors, it will automatically set the flash message to "Post was successfully created" as long as you configure your I18n file:

yaml flash: actions: create: notice: "%{resource_name} was successfully created." update: notice: "%{resource_name} was successfully updated." destroy: notice: "%{resource_name} was successfully destroyed." alert: "%{resource_name} could not be destroyed."

In case the resource contains errors, you should use the failure key on I18n. This is useful to dry up flash messages from your controllers. Note: by default alerts for update and destroy actions are commented in generated I18n file. If you need a specific message for a controller, let’s say, for PostsController, you can also do:

yaml flash: posts: create: notice: "Your post was created and will be published soon"

This responder is activated in all non get requests. By default it will use the keys :notice and :alert, but they can be changed in your application:

ruby config.responders.flash_keys = [ :success, :failure ]

You can also have embedded HTML. Just create a _html scope.

yaml flash: actions: create: alert_html: "<strong>OH NOES!</strong> You did it wrong!" posts: create: notice_html: "<strong>Yay!</strong> You did it!"

See also the namespace_lookup option to search the full hierarchy of possible keys.


Automatically adds Last-Modified headers to API requests. This allows clients to easily query the server if a resource changed and if the client tries to retrieve a resource that has not been modified, it returns not_modified status.


Makes your create and update action redirect to the collection on success.


This responder allows you to use callable objects as the redirect location. Useful when you want to use the respond_with method with a custom route that requires persisted objects, but the validation may fail.

Note: this responder is included by default, and doesn’t need to be included on the top of your controller (including it will issue a deprecation warning).

```ruby class ThingsController < ApplicationController respond_to :html

def create @thing = Thing.create(params[:thing]) respond_with @thing, location: -> { thing_path(@thing) } end end ```

Dealing with namespaced routes

In order for the LocationResponder to find the correct route helper for namespaced routes you need to pass the namespaces to respond_with:

```ruby class Api::V1::ThingsController < ApplicationController respond_to :json

# POST /api/v1/things def create @thing = Thing.create(thing_params) respond_with :api, :v1, @thing end end ```

Configuring your own responder

Responders only provides a set of modules and to use them you have to create your own responder. After you run the install command, the following responder will be generated in your application:

ruby # lib/application_responder.rb class ApplicationResponder < ActionController::Responder include Responders::FlashResponder include Responders::HttpCacheResponder end

Your application also needs to be configured to use it:

```ruby # app/controllers/application_controller.rb require “application_responder”

class ApplicationController < ActionController::Base self.responder = ApplicationResponder respond_to :html end ```

Controller method

This gem also includes the controller method responders, which allows you to cherry-pick which responders you want included in your controller.

ruby class InvitationsController < ApplicationController responders :flash, :http_cache end

Interpolation Options

You can pass in extra interpolation options for the translation by adding an flash_interpolation_options method to your controller:

```ruby class InvitationsController < ApplicationController responders :flash, :http_cache

def create @invitation = Invitation.create(params[:invitation]) respond_with @invitation end


def flash_interpolation_options { resource_name: } end end ```

Now you would see the message "[email protected] was successfully created" instead of the default "Invitation was successfully created."


This gem also includes a responders controller generator, so your scaffold can be customized to use respond_with instead of default respond_to blocks. From 2.1, you need to explicitly opt-in to use this generator by adding the following to your config/application.rb:

ruby config.app_generators.scaffold_controller :responders_controller

Failure handling

Responders don’t use valid? to check for errors in models to figure out if the request was successful or not, and relies on your controllers to call save or create to trigger the validations.

ruby def create @widget = # @widget will be a valid record for responders, as we haven't called `save` # on it, and will always redirect to the `widgets_path`. respond_with @widget, location: -> { widgets_path } end

Responders will check if the errors object in your model is empty or not. Take this in consideration when implementing different actions or writing test assertions on this behavior for your controllers.

ruby def create @widget = @widget.errors.add(:base, :invalid) # `respond_with` will render the `new` template again. respond_with @widget end

Verifying request formats

respond_with will raise an ActionController::UnknownFormat if the request MIME type was not configured through the class level respond_to, but the action will still be executed and any side effects (like creating a new record) will still occur. To raise the UnknownFormat exception before your action is invoked you can set the verify_requested_format! method as a before_action on your controller.

```ruby class WidgetsController < ApplicationController respond_to :json before_action :verify_requested_format!

# POST /widgets.html won’t reach the create action. def create widget = Widget.create(widget_params) respond_with widget end end



Want more examples ? Check out these blog posts:

Bugs and Feedback

If you discover any bugs or want to drop a line, feel free to create an issue on GitHub.

MIT License. Copyright 2020 Rafael França, Carlos Antônio da Silva. Copyright 2009-2019 Plataformatec.