How to create another object when creating a Devise User from their registration form in Rails?

Question

There are different kinds of users in my system. One kind is, let's say, a designer:

class Designer < ActiveRecord::Base
  attr_accessible :user_id, :portfolio_id, :some_designer_specific_field
  belongs_to :user
  belongs_to :portfolio
end

That is created immediately when the user signs up. So when a user fills out the sign_up form, a Devise User is created along with this Designer object with its user_id set to the new User that was created. It's easy enough if I have access to the code of the controller. But with Devise, I don't have access to this registration controller.

What's the proper way to create a User and Designer upon registration?

Answer 1

In a recent project I've used the form object pattern to create both a Devise user and a company in one step. This involves bypassing Devise's RegistrationsController and creating your own SignupsController.

# config/routes.rb
# Signups
get 'signup' => 'signups#new',     as: :new_signup
post 'signup' => 'signups#create', as: :signups  


# app/controllers/signups_controller.rb
class SignupsController < ApplicationController
  def new
    @signup = Signup.new
  end

  def create
    @signup = Signup.new(params[:signup])

    if @signup.save
      sign_in @signup.user
      redirect_to projects_path, notice: 'You signed up successfully.'
    else
      render action: :new
    end
  end
end

The referenced signup model is defined as a form object.

# app/models/signup.rb

# The signup class is a form object class that helps with
# creating a user, account and project all in one step and form
class Signup
  # Available in Rails 4
  include ActiveModel::Model

  attr_reader :user
  attr_reader :account
  attr_reader :membership

  attr_accessor :name
  attr_accessor :company_name
  attr_accessor :email
  attr_accessor :password

  validates :name, :company_name, :email, :password, presence: true

  def save
    # Validate signup object
    return false unless valid?

    delegate_attributes_for_user
    delegate_attributes_for_account

    delegate_errors_for_user unless @user.valid?
    delegate_errors_for_account unless @account.valid?

    # Have any errors been added by validating user and account?
    if !errors.any?
      persist!
      true
    else
      false
    end
  end

  private

  def delegate_attributes_for_user
    @user = User.new do |user|
      user.name = name
      user.email = email
      user.password = password
      user.password_confirmation = password
    end
  end

  def delegate_attributes_for_account
    @account = Account.new do |account|
      account.name = company_name
    end
  end

  def delegate_errors_for_user
    errors.add(:name, @user.errors[:name].first) if @user.errors[:name].present?
    errors.add(:email, @user.errors[:email].first) if @user.errors[:email].present?
    errors.add(:password, @user.errors[:password].first) if @user.errors[:password].present?
  end

  def delegate_errors_for_account
    errors.add(:company_name, @account.errors[:name].first) if @account.errors[:name].present?
  end

  def persist!
    @user.save!
    @account.save!
    create_admin_membership
  end

  def create_admin_membership
    @membership = Membership.create! do |membership|
      membership.user = @user
      membership.account = @account
      membership.admin = true
    end
  end
end

An excellent read on form objects (and source for my work) is this CodeClimate blog post on Refactoring.

In all, I prefer this approach vastly over using accepts_nested_attributes_for, though there might be even greater ways out there. Let me know if you find one!

===

Edit: Added the referenced models and their associations for better understanding.

class User < ActiveRecord::Base
  # Memberships and accounts
  has_many :memberships
  has_many :accounts, through: :memberships
end

class Membership < ActiveRecord::Base
  belongs_to :user
  belongs_to :account
end

class Account < ActiveRecord::Base
  # Memberships and members
  has_many :memberships, dependent: :destroy
  has_many :users, through: :memberships
  has_many :admins, through: :memberships,
                    source: :user,
                    conditions: { 'memberships.admin' => true }
  has_many :non_admins, through: :memberships,
                        source: :user,
                        conditions: { 'memberships.admin' => false }
end

This structure in the model is modeled alongside saucy, a gem by thoughtbot. The source is not on Github AFAIK, but can extract it from the gem. I've been learning a lot by remodeling it.

Answer 2

If you don't want to change the registration controller, one way is to use the ActiveRecord callbacks

class User < ActiveRecord::Base
  after_create :create_designer

  private

  def create_designer
      Designer.create(user_id: self.id) 
  end
end