问题描述
我有这个模型:
class Student < ActiveRecord::Base
has_many :tickets
has_many :movies, through: :tickets
end
class Movie < ActiveRecord::Base
has_many :tickets, dependent: :destroy
has_many :students, through: :tickets
belongs_to :cinema
end
class Ticket < ActiveRecord::Base
belongs_to :movie, counter_cache: true
belongs_to :student
end
class Cinema < ActiveRecord::Base
has_many :movies, dependent: :destroy
has_many :students, through: :movies
has_many :schools, dependent: :destroy
has_many :companies, through: :yard_companies
end
class School < ActiveRecord::Base
belongs_to :company
belongs_to :student
belongs_to :cinema, counter_cache: true
end
class Teacher < ActiveRecord::Base
belongs_to :movie, counter_cache: true
belongs_to :company
end
class Contract < ActiveRecord::Base
belongs_to :company
belongs_to :student
end
class Company < ActiveRecord::Base
has_many :teachers
has_many :movies, through: :teachers
has_many :contracts
has_many :students, through: :contracts
end
如果我在我的 movies_controller.rb 中写这个:
If I write this in my movies_controller.rb:
@students = @movie.cinema.companies.students.all
我有这个错误:
未定义方法 'students' for #Company::ActiveRecord_Associations_CollectionProxy:0x00000007f13d88>
如果我写这个:
@students = @movie.cinema.companies.find(6).students.all
它向我显示了我的 select_collection 中正确的学生.
it shows me the correct students in my select_collection.
如何更好地理解这个过程?
更新:
我需要这部电影的一家电影院的所有学生的 collection_select.
I need the collection_select of every students in companies of a cinema of this movie.
怎么写?
推荐答案
如 Nermin 所述，您正在尝试从一个孩子的集合中请求一个孩子的集合.
As described by Nermin you're trying to request a collection of children, from a collection of children.
您可以使用 collect 收集来自公司的学生:
You could use collect to gather the students from the companies along the lines of:
@movie.cinema.companies.collect(&:students).flatten.uniq
但我认为您最好按照以下方式向学生模型添加范围:
But I think you would do better to add a scope to your Student model along the lines of:
scope :for_companies, ->(_companies) {joins(:companies).where(company: _companies)}
使用Student.for_companies(@movie.cinema.companies)
免责声明:未经测试，但应该是一个起点！
Disclaimer: untested, but should be a starting point!
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