ruby-on-rails - Rails3 has_and_belongs_to_many 定制

Question

预订has_and_belongs_to_many学生
学生has_and_belongs_to_many书籍

在 BooksStudents 模型中，我想添加“状态”字段来存储它是否被租用、购买等。并能够选择例如 @student.books.rented 或 @student.books.where(:books_students=>{:status=>2})

我可以使用 HABTM 做到这一点吗？

Answer 1

据我所知不，您将需要一个 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

所以你可以做类似 @student.books 或 @student.student_books.where(:status =>2)