Question

Consider a model for keeping user id’s of subscribers on a particular comment thread, such that

thread has_many subscribers

where subscribers is of type user.

I feel like generating a new a table for subscribers is overkill. In principle, I’d like to access thread.subscribers to get a list of subscribers- surely there is a ‘lighter’ way?

I’m using Rails 3 with SQLite.

Answer 1

There are two methods you could use.

Options One is to use a habtm relationship like:

class Thread
  has_and_belongs_to_many :users
end

However personally I would use an additional model, so that should you even need it you can specify stuff about subscriptions:

class Thread
  has_many :subscriptions
end

class Subscription
  belongs_to :thread
  belongs_to :user
end

Generally a useful join model is considered better practice.

Additionally I wouldn’t really be worrying about how ‘light’ you database schema is. Databases are very good at what they’re good at, and that’s why we let they do it. Encoding this kind of information as a string or the like as other issues and may even be less efficient.