CrudResponder

Embrace CRUD interface for your models

We should keep controllers skinny and don't repeat ourself, right? But this scaffolded action doesn't look very DRY:

def create
  @post = Post.new(post_params)

  respond_to do |format|
    if @post.save
      format.html { redirect_to @post, notice: 'Post was successfully created.' }
      format.json { render :show, status: :created, location: @post }
    else
      format.html { render :new }
      format.json { render json: @post.errors, status: :unprocessable_entity }
    end
  end
end

You can make it simpler if you don't need to respond to anything but html, or use responders gem.

Let's assume we need only html and also add flash message on error:

def create
  @post = Post.new(post_params)

  if @post.save
    redirect_to @post, notice: 'Post was successfully updated.' }
  else
    flash[:alert] = "Error updating post: #{@post.errors.full_messages.to_sentence}"
    render :edit
  end
end

But it's still not DRY because we have to repeat this code in every controller, and even a different action of the same controller:

def update
  @post = Post.find(params[:id])

  if @post.update(post_params)
    redirect_to @post, notice: 'Post was successfully created.'
  else
    flash[:alert] = "Error creating post: #{@post.errors.full_messages.to_sentence}"
    render :new
  end
end

But the only differences between these actions are:

• Method called on a model
• Action on success
• Action on error
• Text in flash message on success
• Text in flash message on error

And they are repeated over and over again. Let's extract these differences:

def create
  @post = Post.new(post_params)
  crud_respond @post # will call save, set flashes and redirects/render appropriately
end

def update
  @post = Post.find(params[:id])
  @post.assign_attributes(post_params)
  crud_respond @post # also call save
end

def destroy
  @post = Post.find(params[:id])
  crud_respond @post # call destroy because called from destroy action
end

Method to call on the object determined by the name of controller's action.

Installation

Add this line to your application's Gemfile:

gem 'crud_responder'

And then execute:

  $ bundle install

Or install it yourself as:

  $ gem install crud_responder

Generate initial files:

$ rails g crud_responder:install

Usage

Include CrudResponder into your ApplicationController (or whatever base controller you have). Note: generator already has included CrudResponder to Application controller.

class ApplicationController
  include CrudResponder
end

Use crud_respond method with object you need to create, update or destroy. Optionally, you can pass options to this method to override default redirect and render actions

def create
  @post = Post.new(post_params)
  crud_respond @post, success_url: root_path, error_action: :custom_new_action
  # will redirect to root_path in case of success or render :custom_new_action otherwise
end

By default you will be redirected to object show, objects index or back in this order. And render :new when creating object and :edit when updating.

You can specify error_url instead of error_action to be redirected instead of action render in case of error:

def create
  @post = Post.new(post_params)
  crud_respond @post, success_url: root_path, error_url: 'https://google.com'
  # will redirect to root_path in case of success or to https://google.com otherwise
end

You can specify custom flash messages:

def create
  @post = Post.new(post_params)
  crud_respond @post, success_message: 'Yep :)', error_message: 'Nope :('
  # will render flash 'Yep :)' on success or 'Nope :(' on failure instead of default ones
end

You can also specify per-controller default options:

private

def crud_responder_default_options
  { success_url: root_path }
  # will redirect to `root_path` for every successful request in this controller
end

If you need to create a bunch of objects (not just one) you can create wrapper class with same interface. For example, uploading multiple files:

# app/controllers/media_items_controller.rb
class MediaItemsController < ApplicationController
  def create_multiple
    @media_item_multiple = MediaItem::CreateMultiple.new(media_item_create_multiple_params)
    crud_respond @media_item_multiple, success_url: media_items_path
  end

  private

  def media_item_create_multiple_params
    params.require(:media_item_create_multiple).permit(:description, files: [])
  end
end

# app/models/media_item/create_multiple.rb
class MediaItem::CreateMultiple
  include ActiveModel::Model

  attr_accessor :description, :files
  validates :files, presence: true

  def save
    return false unless valid?
    ActiveRecord::Base.transaction do
      files.each do |file|
        MediaItem.create!(description: description,  file: file)
      end
    end
    true
  rescue ActiveRecord::RecordInvalid => e
    errors.add(:base, e.to_s)
    false
  end
end

Now your controllers are skinny again! Also, you are forced to think in terms of CRUD interface to models and REST to controllers.

TODO

• Support for pure API controllers (which is much simpler)
• Testing

Note about pure API controllers. I already use this idea:

# somewhere in base controller for API
protected

def result(object, method = :save, options = {})
  method = :destroy if caller[0][/`.*'/][1..-2] == 'destroy'
  serializable_attrs = *options.fetch(:serializable_attrs, :id)
  if object.send method
    object_json(object, serializable_attrs)
    respond_with object, location: (method == :destroy ? nil : object_url(object))
  else
    fail UnprocessableEntityError, object.errors.full_messages.to_sentence
  end
end

def object_url(object)
  polymorphic_url(object)
rescue NoMethodError
  "there is no show route for #{object.class.name} object"
end

def object_json(object, serializable_attrs)
  object.instance_exec(serializable_attrs) do |attrs|
    @_s_attrs = attrs
    def to_json(*) # don't want to return the whole object on create/update
      hash = {}
      @_s_attrs.each do |attr|
        hash[attr] = try(attr) if try(attr)
      end
      hash.any? ? JSON.generate(hash) : ''
    end
  end
end

I'm thinking of extracting this as well plus adding support for ActiveModelSerializers. Any feedback is welcome.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/olegantonyan/crud_responder. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.