CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-3activerecord
GorrillaMcD
GorrillaMcD

Reputation: 1894

e How to select records that are not associated with a parent model - Rails 3.2

First, my models:

User has_many :subscriptions
     has_many :courses, :through => :subscriptions

Subscription belongs_to :both

Course has_many :subscriptions
       has_many :users, :through => :subscriptions

To get the User's courses that are subscribed is easy enough:

@subscribed_courses = current_user.courses

Now I want to get a list of 5 random courses that the current_user is not associated with (for a "You might also like..." function on the user's homepage). What's the best way to do this? Would it be performant to select all Courses and then, in ruby, limit the hash to just the courses not in the @subscribed_courses instance variable? How would I do that if it's the best way?

Edit:

For example, Course.joins(:subscription) will give me all courses associated with a subscription. I want to query for courses that the user is not subscribed to, including those courses that no one has subscribed to yet (and so, aren't associated with a subscription). Sorry I didn't make that clearer before.

Upvotes: 0

Views: 67

Answers (1)

mikdiet
mikdiet

Reputation: 10018

Course.joins(:subscriptions).where('subscriptions.user_id <> ?', current_user.id).order('random()').limit(5)

Upvotes: 1

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