提问人：Abenezer Daniel 提问时间：11/15/2023 更新时间：11/15/2023 访问量：75
两个表之间的 Rails 双向关系
Rails both way relationship between two tables
问：
在Ruby on Rails中，我试图能够在两个表之间创建双向多对多关系。我想要路由和控制器之间的关系。例如，我希望能够执行以下两项操作：
teachers = school_class.teachers.all
school_classes = teacher.school_classes.all因此，如果您能帮助我进行路由设置、控制器和此问题的模型，我将不胜感激。
我尝试使用has_and_belongs_to_many关联，我认为这是正确的方法，但我无法弄清楚其他任何事情。
答：
1赞
tonystrawberry
11/15/2023
#1
当两个表之间存在关系时，它们之间必然需要一个关系表。many-to-many
因此，首先创建一个模型来创建您的关系表。
rails g model TeacherSchoolClass teacher:reference school_class:reference
然后在 你的 中添加行。models/teacher_school_class.rbbelongs_to
class TeacherSchoolClass < ApplicationRecord
belongs_to :teacher
belongs_to :school_class
end
最后，在 和 中，添加行。models/teacher.rbmodels/school_class.rbhas_many/through
class Teacher < ApplicationRecord
has_many :teacher_school_classes, dependent: :destroy # Will destroy the related teacher_school_classes when teacher is destroyed
has_many :school_classes, through: :teacher_school_classes # Will get all the school_classes for this teacher through the teacher_school_classes table
end
class SchoolClass < ApplicationRecord
has_many :teacher_school_classes, dependent: :destroy # Will destroy the related teacher_school_classes when school_class is destroyed
has_many :teachers, through: :teacher_school_classes # Will get all the teachers for this school_class through the teacher_school_classes table
end
然后，您将能够获得：
- 特定教师的所有学校课程
- 特定学校班级的所有教师
teacher.school_classes # Returns an ActiveRecord::Relation of SchoolClass
school_class.teachers # Returns an ActiveRecord::Relation of Teacher
参考： https://guides.rubyonrails.org/association_basics.html#the-has-many-through-association
评论