Question

我一直在寻找几个小时试图找到一个相互的has_many的最新例子：通过两个实际工作的模型，所以我最终决定我只是问。

我的数据库：

schema.rb

#...
create_table "groups", force: true do |t|
  t.string "group_name"
  t.datetime "created_at"
  t.datetime "updated_at"
end

create_table "memberships", force: true do |t|
  t.integer "student_id"
  t.integer "group_id"
end

create_table "students", force: true do |t|
  t.string "user_name"
  t.string "first_name"
  t.string "last_name"
  t.string "password_digest"
  t.datetime "created_at"
  t.datetime "updated_at"
end
#...

我的模特：

student.rb

class Student < ActiveRecord::Base
  has_secure_password
  validates :password, length: { in: 6..20 }
  validates :user_name, format: {with:/\w{2,7}\.\d{1,4}/}, on: :create
  validates_uniqueness_of :user_name, on: :create
  validates_presence_of :first_name, on: :create
  validates_presence_of :last_name, on: :create
  has_many :memberships,  :dependent => :destroy
  has_many :groups, through: :memberships
  has_many :ratings,  :dependent => :destroy
end

group.rb

class Group < ActiveRecord::Base
  has_many :memberships, :dependent => :destroy
  has_many :students, through: :memberships
  validates_uniqueness_of :group_name
end

membership.rb

class Membership < ActiveRecord::Base
  belongs_to :students
  belongs_to :groups
end

如果我的授权正确地将登录的学生:user_name放入session[:user_name]，如果我想要获得该学生所属的所有小组，那么这将是什么（ S）？我也有兴趣找到特定群体中的学生。

我试过了：

 @current_student = Student.find_by_user_name(session[:user_name])
 @current_groups = @current_student.groups

但我得到了：

未初始化的常量Student :: Groups

我做错了什么？

Answer 1

将membership.rb更改为：

class Membership < ActiveRecord::Base
  belongs_to :student
  belongs_to :group
end

has_many：通过2个模型之间的查询

1 个答案: