Unable to create associations

rubyonrails-talk
1

I have two tables, user & provider and I'm struggling to set up the association between them.

A simplified table structure for the two is:

CREATE TABLE users (     id integer not null,     login string not null,     password string not null )

CREATE TABLE providers (     id integer not null,     user_id integer not null,     ... )

and I've used the generater to create two modules, as follows (cut down)

class User < ActiveRecord::Base   has_one :provider

  def invoices_raised     provider.get_invoices   end

  ....

end

class Provider < ActiveRecord::Base   has_many :invoices   belongs_to :user

  def get_invoices     invoices.find(:all)   end end

I have a controller that calls invoices_raised :

class AccountController < ApplicationController   model :user

  before_filter :get_invoices

  def get_invoices     @user = User.find(@session['user'].id)

    @invoices_raised = @user.invoices_raised   end

  ...

end

but inside the invoices_raised method I get the following error:

You have a nil object when you didn't expect it! The error occured while evaluating nil.get_invoices

I thought that using belongs_to & has_one was supposed to implicitly create a provider instance for me?

2

Bryan Evans wrote:

User.has_one :provider will create an accessor on your User class that retrieves the Provider associated with a given user u (i.e. select * from providers where providers.user_id=u.id). There's not enough info in your post to determine why this method is returning a nil for your User instance; I would need to see the object that you are calling get_invoices on and how it is created.

get_invoices is called :

before_filter :get_invoices, :only => [:my_account]

Thanks for the reply Bryan, I know my understanding of asscociations is poor, and I have read the docs again now (and tbh, I think I need to again) but at that time in the morning, it seemed like the best thing to do .. :wink:

-S