Has One - Belongs to question

Rails
1

I have a User model that has_one BillingProfile and BillingProfile
belongs to a User. How do I retrieve the billing profile corresponding
to that particular user? TIA.

2

class User < ActiveRecord::Base
has_one :billing_profile
end

class BillingProfile < ActiveRecord::Base
belongs_to :user
end

user = User.find(:first)
user.billing_profile

3

I generated the User model by using RESTful Authentication plugin. I
ran the ./script/generate authenticated user sessions command and it
generated the migration for users table. I ran the rake db:migrate. I
also defined the has_one and belongs_to in the User and BillingProfile
class.

My question is currently the BillingProfile table does not have the
user_id foreign key. Do I need to create a separate migration for
that? Thanks again.

4

In my User object I am saving the login id of the user, (after the user
logs
in successfully)

session[:user_key] = user.id

In my BillingProfile show method, I want to retrieve the billling
profile
for that particular user:

billing_profile = BillingProfile.find(:first, :conditions =>
"user_id=‘user_key’ ")

Is the above code the right way to do it? TIA.

5

Yes, the billing_profiles table must have a column of type integer,
named
user_id. It will act as a foreign key to the users table.

6

The way I would probably do it is something like:

@user = User.find(session[:user_key])
@billing_profile = @user.billing_profile

The first line sets the @user instance variable the User object with id
session[:user_key].
The second line grabs a BillingProfile object, in particular, the one
with
user_id = @user.id . It would probably be a good exercise to look at
the
SQL queries generated for these calls.

7

That’s the way to do it…
but you might consider using eager loading so you avoid an extra DB call
(if
you can)

@user = User.find(session[:user_key], :include=>[:billing_profile])
@billing_profile = @user.billing_profile