Question

New to RoR, but am having a stab at building an app – and I’m looking for some advice on my db structure.

I’ve got 4 models/tables: Users > Clients > Jobs > Tasks

The app will work as follows:

1. Users will login
2. They can add Clients
3. They can add Jobs to Clients
4. They can add Tasks to Jobs

So, Tasks belong to Jobs, Jobs belong to Clients, and Clients belong to Users.

I want to query the DB for any one of a Client, a Job, or a Task and also make sure that it belongs to the currently logged-in User. I’m struggling to write a ‘railsy’ join query and design my associations so I can do this.

I know this would be super easy if I had a user_id field in every table, but that doesn’t seem like the right way to do it.

I’ve read the guide at http://guides.rubyonrails.org/association_basics.html, but am still in the dark a little. Can anyone shed some light on how I might structure my DB – and more importantly my associations?

Thx.

Answer 1

I’m not sure, if I understood your question correctly, but I believe this can be a solution:

If you write your associations like this, ActiveRecord will create automatically the joins if you ask for user.jobs or user.tasks.

class User < ActiveRecord::Base
  has_many :clients
  has_many :jobs, :through => :clients
  has_many :tasks, :through => :jobs
end

For more Information see the Rails-Api-Documentation

If you want to get everything for a user in one request. You can do this:

user.clients.joins(:jobs => :tasks)