Question

Given two models:

class User < ActiveRecord::Base
  attr_accessible :name, :user_status

end

class UserStatus < ActiveRecord::Base
  attr_accessible :descr
end

The user.user_status column is intended to be a single ID which can be used to join against UserStatus for additional information, such as status icon and description.

UserStatus is a read-only reference table which will have very few rows, all unique. Let’s say it has only four rows:

{ :id => 0, :descr => 'New' },
{ :id => 1, :descr => 'Banned' },
{ :id => 2, :descr => 'Active' },
{ :id => 3, :descr => 'Unverified' }

Should I bother with ActiveRecord associations for reference tables? If so, what is the proper ActiveRecord association if I want to (or must) store the associated UserStatus ID in the user table? From what I can tell, based on the documentation, ‘User belongs_to :user_status’ is my best bet, but linguistically this is failure; because a User does not “belong to” a status, a user is in a state or has a status. Or is this just too hair-splitting of me?

Answer 1

belongs_to doesn’t always make linguistic sense, but in this case it’s just what you want.

UserStatus has_many :users
User belongs_to :user_status

Which also allows the status to find all users in that state, which can be useful.

naughtyPeople = UserStatus.where(descr: 'Banned').users

What’s more important, linguistically, is the API you settle on to get this data.

User.find(123).user_status.descr

That kind of sucks. It has the relations you want, but the API is pretty verbose.

class User
  def status
    user_status.descr
  end
end

User.find(123).status

Much better.

Or even possibly this!

class User
  def status
    user_status.descr
  end

  def status=(status_string)
    self.user_status = UserStatus.where(descr: status_string).first
  end
end

user = User.find(123)
user.status = 'Banned'
user.user_status #=> { id: 3, descr: "Banned" }

How far you want to massage it is up to you.