first_or_create by email and then save the nested model

问题

I two models User and Submission as follows:

class User < ActiveRecord::Base
  # Associations
  has_many :submissions
  accepts_nested_attributes_for :submissions

  # Setup accessible (or protected) attributes for your model
  attr_accessible :email, :name, :role, :submission_ids, :quotation_ids, :submissions_attributes

  validates :email, :presence => {:message => "Please enter a valid email address" }
  validates :email, :uniqueness => { :case_sensitive => false }
end

class Submission < ActiveRecord::Base
  belongs_to :user
  attr_accessible :due_date, :text, :title, :word_count, :work_type, :rush, :user, :notes

  validates :work_type, :title, :text,:presence => true
  validates :text, :length => { :minimum => 250 }
  validates :word_count, :numericality => { :only_integer => true }
end

I have a form which collects the data required by these two models. Users controller:

def index
  @user = User.new
  @user.submissions.build
end

def create
  @user = User.where(:email => params[:user][:email]).first_or_create(params[:user])

  if @user
    redirect_to :root
  else
    render 'pages/index'
  end
end

What I want to do is first check if the user already exists in the system by the email submitted. If so then I want to create a submission for that user. Otherwise create the user and submission at the same time.

I'm confused on how to do this with the first_or_create method.

Any help appreciated.

回答1:

first_or_create accepts a block. So you could do it as follows:

@user = User.where(:email => params[:user][:email]).first_or_create do |user|
  # This block is called with a new user object with only :email set
  # Customize this object to your will
  user.attributes = params[:user]
  # After this, first_or_create will call user.create, so you don't have to
end

回答2:

Since your use case is a little more complicated, it may not hurt to split this up into two separate actions. If you want this to occur atomically, you can throw it in a transaction.

User.transaction do
  # Create the user if they don't already exist
  @user = User.where(:email => params[:user][:email]).first_or_create

  # Update with more attributes, and create nested submissions
  @user.update_attributes(params[:user])
end

回答3:

Hey I think it should be something like that

@user = User.first_or_create(params[:user])

Then in user model

def first_or_create(params)
  unless user = User.where(:email => params[:email]).first # try to find user
    user = User.create(email: params[:user]) 
    # it should create also submission because of accepts_nested_attributes_for 
  else #user exsists so we need to create submission for him
    user.submissions.create(params[:submissions])
  end
end

来源：https://stackoverflow.com/questions/16644756/first-or-create-by-email-and-then-save-the-nested-model