Rails 关联 - 如何为不同种类的用户设置关联? [英] Rails associations - how can I set up associations for different varieties of users?

问题描述

我正在创建一个由学校、课程、学生和教师组成的网络应用.

I'm creating a web app which consists of schools, courses, students, and teachers.

一所学校可以开设多门课程，而一门课程可以有一名老师和多名学生.

A school can have many courses and a course has one teacher and many students.

我遇到的问题是，单个用户可能是一门课程的老师，但可能是另一门课程的学生(甚至是不同学校课程的学生或老师).我不想为教师创建一个模型，为学生创建一个单独的模型，因为我想在一个地方跟踪我的所有用户.有一个注册表，其中列出了哪些用户被注册为课程的学生.

The problem I am running into is that a single user could be a teacher of one course, but a student in another course (or even a student or teacher in a course in a different school). I don't want to create a model for teachers and a separate model for students because I would like to track all my users in one place. There is an enrollment table which lists which users are enrolled as students in a course.

我想做如下事情:

class School < ActiveRecord::Base
  has_many :courses
  has_many :students :through enrollments
  has_many :teachers :through courses
end

class Course < ActiveRecord::Base
  has_one :teacher
  belongs_to :school
  has_many :students :through enrollments
end

class User < ActiveRecord::Base
  has_many :courses
  has_many :schools
end

但如果我只有一个用户表而不是两个单独的学生和教师表，这将不起作用.

But if I have only a users table and not two separate students and teachers tables, this won't work.

相反，我必须做类似的事情

Instead, I would have to do something like

class School < ActiveRecord::Base
  has_many :users [that are teachers]
  has_many :users :through enrollments [that are students]
end

如何设置我的模型和关联以使其正常工作?

How can I set up my model and associations to make this work?

谢谢.

推荐答案

使用继承.

教师和学生继承自用户模型.可以参考http://api.rubyonrails.org/classes/ActiveRecord/Base.html 了解更多信息.请务必在您的用户表中创建类型"列或等效列.

Teachers and students are inherited from the users model. You can consult http://api.rubyonrails.org/classes/ActiveRecord/Base.html for further information. Be sure to create a "type" column or equivalent in your User table.

class User < ActiveRecord::Base
end

class Student < User
end

class Teacher < User
end

Rails 会单独对待它们，但它们仍将存在于 User 表中.如果您需要进一步的帮助，请告诉我

Rails will treat them individually, but they will still exist in the User table.Let me know if you need further assistance

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