How to define the relationship between these 3 models?

Question

I have 3 models like this-

| User       | Skill       | SubSkills    |
|:-----------|------------:|:------------:|
| Name       |Title        |     Title    |  
| Trade      |Trade        |    Done(bool)|    

What the models should look like-

class User < ActiveRecord::Base
  has_and_belongs_to_many :skills
end

class Skill < ActiveRecord::Base
  has_and_belongs_to_many :users
  has_many :sub_skills
end

class SubSkills < ActiveRecord::Base
  belongs_to :user #not sure
  belongs_to :skill
end

Basically skills are the same for every user of the same trade and one user has many skills. Each skill has many subskills but a subskill is done(or not) for a particular user.

Is this possible? Whats a better way to design this relationship? How will the routes be defined for this? Like which resource will be nested under which resource?

Answer 1

I think you are close, but try this:

class SubSkills < ActiveRecord::Base
  belongs_to :skill
  has_one :user, through: :skill
end

The routes could be done a number of ways: not nested, nested, shallow nesting ...etc. (check out Rails Routing from the Outside In , particularly section 2.7.1 Limits to Nesting ). It really depends on the needs of your application.

You could do something like:

/users/:id/skills/:skill_id/sub_skills/:sub_skill_id

..thus in your routes.rb you would have:

resources :users do
  resources :skills do
    resources :sub_skills
  end
end

If you want to be able to access all sub_skills directly from the user like user.sub_skills rather than via a specific skill like user.skills.last.sub_skills you would have to add the association to the User model like this:

class User < ActiveRecord::Base
  has_and_belongs_to_many :skills
  has_many :sub_skills, through: :skills
end