Question

User has_one UserProfile which has_one Community.

Given a community_id, I want a list of emails from the Users table.

How do I get a list of all User.email where community_id = 5?

The best I can find (which does work) is:

User.select(:email).joins(:user_profile).merge(UserProfile.for_community(5))

But it seems brute-force… is there not a way to do something simpler along the lines of this below?

User.user_profile.community(5)

Answer 1

I don’t think you know what your code does…

If the UserProfile has_one community, then the communities table must have a column titled user_id. That means there is only one User associated with any given community id.

To solve your question, as stated, you could delegate the user method to the user_profile.

class Community < ActiveRecord::Base
  belongs_to :user_profile
  delegate :user, to: :user_profile
end

Then you could do Community.find(community_id).user.email

Hope that helps.