Question

预订has_and_belongs_to_many学生学生has_and_belongs_to_many图书

在BooksStudents模型中，我想添加“status”字段来存储，如果它是租来的，买了..etc。并且能够选择例如@student.books.rented或@student.books.where(:books_students=>{:status=>2})

我可以用HABTM做到吗？

Answer 1

AFAIK不，你需要一个has_many：通过设置..

class Book < ActiveRecord::Base
  has_many :books_students  
  has_many :students, :through => :books_students
end

class BooksStudent  < ActiveRecord::Base
  belongs_to :book  
  belongs_to :student 
end 

classStudent  < ActiveRecord::Base 
  has_many :books_students  
  has_many :books, :through => :books_students  
end

因此您可以执行@student.books或@student.student_books.where(:status =>2)

之类的操作

rails3 has_and_belongs_to_many自定义

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