多对多关联出现 Could not find the source association (s) 错误

akayuki — Mon, 08 May 2017 14:54:27 +0800

在做一个学生作业系统的时候出现的问题，Student 通过 Enrollment 与 Course 多对多关联，先上代码

class Course < ApplicationRecord
    has_many   :enrollments
    has_many   :students, :through => :enrollments, :source => :user, :conditions => { :type => 'Student' }
end

class Student < User
    has_many   :enrollments
    has_many   :courses, :through => :enrollments, :source => :course
end

class Enrollment < ApplicationRecord
    belongs_to :course
    belongs_to :student
end

在 rails console 里执行 student.courses 的时候系统提示 ActiveRecord::HasManyThroughSourceAssociationNotFoundError: Could not find the source association(s) :course in model Enrollment. Try 'has_many :courses, :through => :enrollments, :source => <name>'. Is it one of ?

Student 这个 model 是从 User 单表继承过来的，source 那里应该填 user 还是 student？两种都试了下但是一样会出错，能麻烦各位帮忙看一下吗？

akayuki (akayuki)

多对多关联出现 Could not find the source association (s) 错误