在Rails中创建多个一对多关系

Question

This question almost answers it, but I still think it's overkill. Trouble with Rails has_many relationships

I really just want a to do assignments like this assign

@user.browsing_location = location1
@user.home_location = location2

I've done a lot of googling around and all the information is contradictory, or explains setting up many to many relationships, and explains methods using an intermediary table. But really all the database should need is for the user table to have two differently names id fields for the locations. Will something like the following work?

User Class

  class User < ActiveRecord::Base
  #locations created by this user
  has_many :locations, :foreign_key => :creator_id

  #locations for browsing and visiting
  belongs_to :browsing_location, :source => :location
  belongs_to :home_location, :source => :location

end

Location Class

class Location < ActiveRecord::Base
  #Users who are just browsing this location now
  has_many :browsing_users, :foreign_key => :browsing_location_id, :source => :users
  #Users who are living here now
  has_many :home_users, :foreign_key => :home_location_id, :source => :users

  #User who created this location
  has_one :user
end

Quite a lot of my models will need relationships like this so I would like to avoid having to create extra tables for this.

Answer 1

It appears that you're attempting to have two tables that inherit the location class, browsing_location and home_location and two tables that inherit the user class, browsing_user and home_user. For Rails 3:

You've got the general idea, but it appears that you have mixed things up a bit. :source is used for many to many relationships to determine which association to use. What you appear to need instead is :class_name

I would need to see your table definitions for users and locations to make sure you're using :foreign_key attribute correctly.

user.rb

class User < ActiveRecord::Base
  # locations created by this user
  has_many :locations, :foreign_key => :creator_id

  # I'm assuming the locations belong to the user, as you're end goal was stated as  
  # the ability to call set user.browsing_location and user.home_location 
  # that would mean that browsing_location and home_location would need to belong to
  # the User class, not the other way around.  
  has_many :browsing_locations, :class_name => :location
  has_many :home_locations, :class_name => :location

end

class Location < ActiveRecord::Base

  # User who created the location
  belongs_to :user

  # Users who are just browsing this location now
  has_many :browsing_users, :class_name => :users
  # Users who are living here now
  has_many :home_users, :class_name => :users

end