Creating has_one models on save

rubyonrails-talk
1

What is the best practice to create has_one (always exist) model relationships when creating the parent model.

eg: class User < ActiveRecord::Base   has_one :balance end

class Balance < ActiveRecord::Base   belongs_to :user end

A User always has a Balance

I would like to create the Balance model when the User is saved.

There is 3 (maybe more choices to accomplish this), which one is the best practice:

1. Create the Balance model and associate it to the User from the controller that is creating the User model.

2. Do it in the User model with after_create :create_balance

3. Do it in a UserObeserver:

class UserObserver < ActiveRecord::Observer   def after_create(user)     balance = Balance.new(:amount => 0)     balance = customer     balance.save   end end

Thanks! If this has been covered before, sorry, but just not finding the right search terms to limit results.

2

What is the best practice to create has_one (always exist) model

relationships when creating the parent model.

eg:

class User < ActiveRecord::Base

has_one :balance

end

class Balance < ActiveRecord::Base

belongs_to :user

end

A User always has a Balance

I would like to create the Balance model when the User is saved.

There is 3 (maybe more choices to accomplish this), which one is the

best practice:

  1. Create the Balance model and associate it to the User from the

controller that is creating the User model.

  1. Do it in the User model with after_create :create_balance

  2. Do it in a UserObeserver:

class UserObserver < ActiveRecord::Observer

def after_create(user)

balance = Balance.new(:amount => 0)

balance = customer

balance.save

end

end

Thanks! If this has been covered before, sorry, but just not finding

the right search terms to limit results.

Albert, you should be able to do the following:

class User < ActiveRecord::Base

after_save :create_balance

protected

def create_balance

 balance = Balance.new( :amount => 0 )

# fill in any additional attributes

balance.save!

self.balance = balance # associate the balance to the user

end

end

BTW, you can use an after_save filter to invoke the create_balance method when you save the

user instance.

Good luck,

-Conrad

3

Thanks Conrad...

I think after_create is the better filter to use, otherwise the Balance is reset to 0 everytime there is an update to the User.

4

Albert Wong wrote:

What is the best practice to create has_one (always exist) model relationships when creating the parent model.

In addition to the technical answers...

Isn't the relation "always has one" really the relation "is part of"?

Why all the fields are not in the same record?