Rails中的多對多關聯值無法保存在數據庫中。

Question

我有許多關聯的用戶和角色表。我的數據庫有用戶，角色和role_users表。基本上我想將用戶的角色保存在role_users表中，該表基本上是用戶和角色的連接表。我從角色表中的用戶頁面上獲取user'role，並想將它們保存在role_users表中。但我無法將用戶的角色保存在role_users表中。我已經在用戶的「創建控制器」中編寫代碼以將數據保存在role_users表中，但沒有發生。

users_controller.rb

class Admin::UsersController < Admin::BaseController 
    before_filter :find_user, :only => [:show, :edit, :update, :destroy] 
    def index 
    @users = User.all(:order => :email) 
    @roles = Role.all 
    end 

    def show 
    end 

    def new 
    @user = User.new 
    end 

    def create 
    is_admin = params[:user].delete(:is_admin) == "1" 
    @user = User.new(params[:user]) 
    **@user_role = RoleUser.new({:user_id => @user.id, :role_id => params[:role_user]})** 
    #@user_role.role_id = params[:role_id] 
    #@user_role.user_id = current_user.id 
    @user_role.save 

    @user.is_admin = is_admin 
    if @user.save 
    flash[:notice] = "User has been created." 
    redirect_to admin_users_path 
    else 
    flash[:alert] = "User has not been created." 
    render :action => :new 
    end 
end 

    def edit 
    end 

    def update 
    if params[:user][:password].empty? 
     params[:user].delete(:password) 
    end 

    set_admin 
    if @user.update_attributes(params[:user]) 
     flash[:notice] = "User has been updated." 
     redirect_to admin_users_path 
    else 
     flash[:alert] = "User has not been updated." 
     render :action => :new 
    end 
    end 

    def destroy 
    if @user == current_user 
     flash[:alert] = "You cannot delete yourself!" 
    else 
     @user.destroy 
     flash[:notice] = "User has been deleted." 
    end 
    redirect_to admin_users_path 
    end 

    private 

    def find_user 
    @user = User.find(params[:id]) 
    end 

    def set_admin 
    is_admin = params[:user].delete(:is_admin) == "1" 
    @user.is_admin = true 
    end 
end 

schema.rb

# encoding: UTF-8 
# This file is auto-generated from the current state of the database. Instead 
# of editing this file, please use the migrations feature of Active Record to 
# incrementally modify your database, and then regenerate this schema definition. 
# 
# Note that this schema.rb definition is the authoritative source for your 
# database schema. If you need to create the application database on another 
# system, you should be using db:schema:load, not running all the migrations 
# from scratch. The latter is a flawed and unsustainable approach (the more migrations 
# you'll amass, the slower it'll run and the greater likelihood for issues). 
# 
# It's strongly recommended to check this file into your version control system. 

ActiveRecord::Schema.define(:version => 20130601093644) do 




    create_table "role_users", :force => true do |t| 
    t.integer "role_id" 
    t.integer "user_id" 
    t.datetime "created_at", :null => false 
    t.datetime "updated_at", :null => false 
    end 

    create_table "roles", :force => true do |t| 
    t.string "name" 
    t.datetime "created_at", :null => false 
    t.datetime "updated_at", :null => false 
    end 

    create_table "team_users", :force => true do |t| 
    t.integer "team_id" 
    t.integer "user_id" 
    t.integer "team_lead_id" 
    t.datetime "created_at", :null => false 
    t.datetime "updated_at", :null => false 
    end 

    create_table "teams", :force => true do |t| 
    t.string "name" 
    t.datetime "created_at", :null => false 
    t.datetime "updated_at", :null => false 
    t.integer "team_lead_id" 
    end 

    create_table "users", :force => true do |t| 
    t.string "email",     :default => "", :null => false 
    t.string "encrypted_password",  :default => "", :null => false 
    t.string "reset_password_token" 
    t.datetime "reset_password_sent_at" 
    t.datetime "remember_created_at" 
    t.integer "sign_in_count",   :default => 0 
    t.datetime "current_sign_in_at" 
    t.datetime "last_sign_in_at" 
    t.string "current_sign_in_ip" 
    t.string "last_sign_in_ip" 
    t.datetime "created_at",        :null => false 
    t.datetime "updated_at",        :null => false 
    t.boolean "is_admin" 
    t.string "username" 
    t.string "first_name" 
    t.string "last_name" 
    t.string "contact_no" 
    t.date  "birth_date" 
    t.boolean "is_active" 
    t.date  "joining_date" 
    t.string "avatar_url" 
    t.boolean "is_hr" 
    t.boolean "is_manager" 
    t.string "designation" 
    t.string "user_code" 
    t.string "user_role" 
    end 

    add_index "users", ["email"], :name => "index_users_on_email", :unique => true 
    add_index "users", ["reset_password_token"], :name => "index_users_on_reset_password_token", :unique => true 

end 

_form.html.erb（用於創建新用戶）

<div style="margin-left:200px"> 
<%= form_for [:admin, @user] do |f| %> 

    <% @user.errors.full_messages.each do |msg| %> 
     <li><%= msg %></li> 
    <% end %> 


    <div style=" margin-top:10px"> 
    <%= f.label :first_name, :class => 'control-label' %> 
    <div class=""> 
     <%= f.text_field :first_name, :class => 'text_field' %> 
    </div> 
    </div> 
    <div style="margin-left:350px; margin-top:-65px"> 
    <%= f.label :last_name, :class => 'control-label' %> 
    <div class=""> 
     <%= f.text_field :last_name, :class => 'text_field' %> 
    </div> 
    </div> 

    <div style=" margin-top:10px"> 
    <%= f.label :user_code, :class => 'control-label' %> 
    <div class=""> 
     <%= f.text_field :user_code, :class => 'text_field' %> 
    </div> 
    </div> 

    <div style="margin-left:350px; margin-top:-65px"> 
    <%= f.label :email, :class => 'control-label' %> 
    <div class=""> 
     <%= f.text_field :email, :class => 'text_field' %> 
    </div> 
    </div> 

    <div style=" margin-top:10px"> 
    <%= f.label :contact_no, :class => 'control-label' %> 
    <div class=""> 
     <%= f.text_field :contact_no, :class => 'text_field' %> 
    </div> 
    </div> 
    <div style="margin-left:350px; margin-top:-65px"> 
    <%= f.label :birth_date, :class => 'control-label' %> 
    <div class=""> 
     <%= f.text_field :birth_date, :class => 'datepicker ' %> 
    </div> 
    </div> 

    <div style=" margin-top:10px"> 
    <%= f.label :joining_date, :class => 'control-label' %> 
    <div class=""> 
     <%= f.text_field :joining_date, :class => 'datepicker ' %> 
    </div> 
    </div> 

    <div style="margin-left:350px; margin-top:-65px"> 
    <%= f.label :password, :class => 'control-label' %> 
    <div class=""> 
     <%= f.password_field :password, :class => 'password-field' %> 
    </div> 
    </div> 
<div style="margin-left:0px; margin-top:00px"> 
    <%= f.label :designation , :class => 'control-label' %> 
    <select name="user[designation]"> 
    <option value="">Please select</option> 
    <option value="Administrator">Administrator</option> 
    <option value="User">Trainee</option> 
    <option value="Software Engineer">Software Engineer</option> 
    <option value="Senior Software Engineer">Senior Software Engineer</option> 
    <option value="Quality Engineer">Quality Engineer</option> 
    <option value="Team Lead">Team Lead</option> 
</select> 
</div> 

<label> User Role</label> 
<%= select_tag "role_id", options_from_collection_for_select(Role.all, "id", "name"), :style => "width:270px; height:35px" %> 

<div style="margin-top:20px"> 
    <%= f.check_box :is_active %> 
    <div class=""> 
     <%= f.label :is_active, "Is an active user?", :class => 'control-label' %> 
    </div> 
    </div> 
    <div style="margin-left:190px; margin-top:-35px"> 
    <%= f.check_box :is_admin %> 
    <div class=""> 
     <%= f.label :is_admin, "Is an admin?", :class => 'control-label' %> 
    </div> 
    </div> 


    <div style="margin-left:00px; margin-top:15px"> 
    <%= f.check_box :is_hr %> 
    <div class=""> 
     <%= f.label :is_hr, "Is hr?", :class => 'control-label' %> 
    </div> 
    </div> 

    <div style="margin-left:190px; margin-top:-35px"> 
    <%= f.check_box :is_manager %> 
    <div class=""> 
     <%= f.label :is_manager, "Is Manager?", :class => 'control-label' %> 
    </div> 
    </div> 

    <div style="margin-left:00px; margin-top:30px"> 
    <%= f.submit :class => 'btn btn-primary' %> 

    <div style="margin-left:130px;margin-top:-32px"> 
    <%= link_to t('.back', :default => t("helpers.links.back")), 
    admin_users_path, :class => 'btn' %> 
    </div> 
</div> 
<% end %> 
</div> 

user.rb

class User < ActiveRecord::Base 
has_many :roles, through: :role_users 
has_many :role_users 
    # Include default devise modules. Others available are: 
    # :token_authenticatable, :confirmable, 
    # :lockable, :timeoutable and :omniauthable 
    devise :database_authenticatable, :registerable, 
     :recoverable, :rememberable, :trackable, :validatable 

    # Setup accessible (or protected) attributes for your model 
    attr_accessible :username, :email, :password, :password_confirmation, 
    :remember_me, :first_name, :last_name, :is_admin, :contact_no, :birth_date, 
    :joining_date, :is_active, :is_hr, :is_manager, :user_code, :designation 
    # attr_accessible :title, :body 
end 

role_user.rb

class RoleUser < ActiveRecord::Base 
    belongs_to :user 
    belongs_to :role 
    attr_accessible :role_id, :user_id 
end 

role.rb

class Role < ActiveRecord::Base 
    attr_accessible :name 
    has_many :users, through: :role_users 
    has_many :role_users 

end 

總之，我想user'role保存role_users表這是用戶和角色的連接表。爲此，我已經在users_controller.rb

@user_role = RoleUser.new({:user_id => @user.id, :role_id => params[:role_user]}) 

寫下面的代碼但是，數據不保存在數據庫中。

Answer 1

在創建RoleUser時，您的User實例中還沒有ID。

def create 
    is_admin = params[:user].delete(:is_admin) == "1" 
    @user = User.new(params[:user]) 

    # @user is not saved here and has no id 

    **@user_role = RoleUser.new({:user_id => @user.id, :role_id => params[:role_user]})** 

    @user_role.save 

    # based on your validations, it's likely that this @user_role.save is returning false 

在與星星的界限處，@user已被創建但未保存。在保存User之後，嘗試構建您的RoleUser實例。

嘗試保存RoleUser此行之後：if @user.save