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I'm wondering if there's such a thing as a best practice for one to many relationships. I'm planning a simple rails app that will have a relational DB with either of the following scenarios:

  • Scenario A ERD: A user can have zero or many lists, and a list can have zero to many items. I know that this means a user cannot directly create an item. An item can only be created through a list. An item actually belongs to a list, and a list belongs to a user.

  • Scenario B ERD: A user can have zero or many lists, and the user can also have zero or many items. This means everything is directly associated to the user. Items will be associated to a list due to a foreign key via a list ID.

Is there a best practice to use/not use either scenario?

Thanks in advance!

codejoe
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  • what information is contained in the lists and items? the best practice can be suggested based on that information and more specifically your use case. – coffeebytes May 26 '17 at 03:07
  • The information in lists/items would strings - lists would be something like a to-do list or a shopping list. – codejoe May 26 '17 at 13:31

1 Answers1

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Scenario A is a better approach. 

class User < ActiveRecord::Base
  has_many :lists
  has_many :items, :through => :lists
end

class List < ActiveRecord::Base
  has_many :items
end
coffeebytes
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