CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-4rails-activerecord
Don P
Don P

Reputation: 63637

Rails: associations - User has_many Model1, and Model1 has_many Model2

A "User" has many "datasets". A "dataset" has many "graphs". How should this be modeled using Rails Associations? Is anything wrong with this setup?

Basically a user can upload many datasets. For each dataset, a user can create several graphs from it. I will need to "get all graphs for a user" and "get all graphs for a dataset".

Models

class User < ActiveRecord::Base
    has_many :datasets
    has_many :graphs, through: :datasets
end

class Dataset < ActiveRecord::Base
    belongs_to :user
    has_many :graphs
end

class Graph < ActiveRecord::Base
  belongs_to :dataset
  belongs_to :user # Do I need this line? Or is it implicit since it belongs to dataset?
end

Tables

Users

id, email

Datasets

id, user_id, name

Graphs

id, dataset_id, type # Do I need "user_id" in here also?

Upvotes: 0

Views: 59

Answers (1)

sevenseacat
sevenseacat

Reputation: 25029

It looks OK apart from the Graph belonging to User part. If Rails supported belongs_to :through, it could be used here, but as it is, having the user_id on the Graph table is not necessary - a Graph's user can simply be retrieved through the Dataset.

Upvotes: 0

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