Question

根据命名约定，我正在使用has_many :through关联来创建用户并分配角色。如果我错了或可以做出任何改进，请随时指导我

create_table "roles", force: :cascade do |t|
  t.string "name"
  t.boolean "active"
  t.integer "counter"
  t.datetime "created_at", null: false
  t.datetime "updated_at", null: false 
end

create_table "users", force: :cascade do |t|
  t.string "first_name"
  t.string "last_name"
  t.string "email"
  t.string "photo"
  t.datetime "created_at", null: false
  t.datetime "updated_at", null: false 
end

我使用以下命令创建了关联

rails g model UserRole role:references user:references

create_table "user_roles", force: :cascade do |t|
  t.integer "role_id"
  t.integer "user_id"
  t.datetime "created_at", null: false
  t.datetime "updated_at", null: false
  t.index ["role_id"], name: "index_user_roles_on_role_id"
  t.index ["user_id"], name: "index_user_roles_on_user_id" 
end   

class Role < ActiveRecord::Base
  has_many :user_roles
  has_many :users, through: :user_roles 
end

class User  < ActiveRecord::Base
  has_many :user_roles
  has_many :roles, through: :user_roles 
end

class UserRole < ApplicationRecord
  belongs_to :user
  belongs_to :role
end

当我使用以下命令运行控制台时：

 r1=Role.create(name:"admin",active:true)        
 r2=Role.create(name:"player",active:true)  
 u1 = User.create(first_name:"alex", roles: [r1,r2])

我遇到以下错误：

 Traceback (most recent call last):
   2: from (irb):3
   1: from app/models/user_role.rb:1:in `<main>' NameError (uninitialized constant ApplicationRecord)

我是Rails的初学者，请在正确的指导下帮助我

Answer 1

看起来您没有ApplicationRecord模型（您不必使用Rails 5+即可，实际上，在更新之前采用此模型是一个好主意）：

class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true
end

Answer 2

您应该这样做：

u1 = User.create(first_name:"alex")
u1.roles.create([{name:"admin",active:true}, {name:"player",active:true}])

has_many中的NameError（未初始化的常量ApplicationRecord）通过关联

2 个答案: