Rails3中has_and_belongs_to_many定制

Question

书has_and_belongs_to_many学生
学生has_and_belongs_to_many书籍

在BooksStudents模式，我想添加“状态”字段来存储，如果是租来的，买了..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吗？

Answer 1

AFAIK没有，你将需要的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 

所以你可以做这样的事情@student.books或@student.student_books.where(:status =>2)