Rails 3模型继承

Question

I have three models: Users, which belongs to Concerts, which belongs to Regions. A User listening to a Concert in a Region. Model belongs_to relationships set up respectively.

In the Concerts controller, I count the number of Users listening to a Concert like this:

@listeners = @concert.users.count

However, I want to list the number of listeners per concert at the region level. In my Region controller I want to do something like this:

@all_listeners = @region.concert.users.count . The number of listeners of each concert, in each region. I know this code is not correct but that is the general idea. Any point in the right direction appreciated.

Answer 1

Add a has_many :through to your Region class.

class User < ActiveRecord::Base
  belongs_to :concert
end

class Concert < ActiveRecord::Base
  belongs_to :region
  has_many :users
end

class Region < ActiveRecord::Base
  has_many :concerts
  has_many :users, :through => :concerts
end

Then you can count the users in a region as so:

@all_listeners = @region.users.count