我正在完成我的第一个Rails项目。我正在创建一个用户登录并创建一个板的应用程序，该板特定于用户的ID。在该板内，用户可以创建列表。每个列表应该与该板的ID绑定。我遇到的问题是创建一个列表。它没有保存。我看到的具体错误是Could not find the association :memberships in model List我可以看到列表被映射到Board的ID存在问题。当我查看Rails服务器的输出时，我看到显示一块板（应该显示该板的所有列表）没有用户ID或板ID。
显示用户的主板
Started GET "/boards" for ::1 at 2016-10-12 14:26:33 -0400
Processing by BoardsController#index as HTML
User Load (0.1ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
Board Load (0.1ms) SELECT "boards".* FROM "boards" WHERE "boards"."user_id" = ? [["user_id", 1]]
CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
Rendered boards/index.html.erb within layouts/application (3.4ms)
Rendered layouts/_flash.html.erb (0.1ms)
Completed 200 OK in 168ms (Views: 166.1ms | ActiveRecord: 0.2ms)
VS显示该用户的列表
Started GET "/lists.3" for ::1 at 2016-10-12 14:28:26 -0400
Processing by ListsController#index as
User Load (0.1ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
List Load (0.3ms) SELECT "lists".* FROM "lists"
Rendered lists/index.html.erb within layouts/application (2.3ms)
Rendered layouts/_flash.html.erb (0.1ms)
Completed 200 OK in 181ms (Views: 169.2ms | ActiveRecord: 0.9ms)
相关代码......
模型
board.rb
class Board < ActiveRecord::Base
belongs_to :owner, class_name: "User", foreign_key: "user_id"
has_many :lists
has_many :memberships
has_many :members, :through => :memberships, :source => :user
has_many :lists, :through => :memberships, :source => :board
validates_presence_of :title
validates_presence_of :owner
def is_private?
return self.is_private
end
end
list.rb
class List < ActiveRecord::Base
belongs_to :board
has_many :cards
has_one :board, :through => :memberships, :source => :board
validates_presence_of :title
validates_presence_of :board
end
user.rb
class User < ActiveRecord::Base
has_many :boards
has_many :lists
has_many :cards
has_many :memberships
has_many :board_memberships, :through => :memberships, :source => :board
has_many :list_memberships, :through => :memberships, :source => :board
has_secure_password
validates :password,
length: { :minimum => 8 },
presence: true
validates :username,
uniqueness: true,
presence: true
validates_confirmation_of :password
end
membership.rb
class Membership < ActiveRecord::Base
belongs_to :user
belongs_to :board
validates :user, presence: true, uniqueness: { scope: :board, message: "User is already a member of that board" }
validates :board, presence: true
end
控制器
boards_controller.rb （我这里只添加了相关部分）
class BoardsController < ApplicationController
before_action :set_board, only: [:show, :edit, :update, :destroy]
before_action :authenticate, except: [:show]
before_action :authorize, except: [:show]
before_action :authorize_owner, only: [:edit, :update, :destroy]
before_action :authorize_membership, only: [:show]
# GET /boards
# GET /boards.json
def index
@boards = current_user.boards
end
# GET /boards/1
# GET /boards/1.json
def show
@lists = current_user.board_id
end
private
def set_board
@board = Board.find(params[:id])
end
def board_params
params.require(:board).permit(:title, :is_private)
end
def authorize_owner
if current_user != @board.owner
redirect_to root_url, :notice => 'Board not found or inaccessible' and return
end
end
def authorize_membership
return
if @board.is_private?
if !authenticate
redirect_to root_url, :notice => 'Please login first' and return
end
if @board.owner != current_user || !@board.members.include?(current_user)
redirect_to root_url, :notice => 'Board not found or inaccessible' and return
end
end
end
# POST /boards
# POST /boards.json
def create
@board = Board.new(board_params)
@board.owner = current_user
respond_to do |format|
if @board.save
format.html { redirect_to @board, notice: 'Board was successfully created.' }
format.json { render :show, status: :created, location: @board }
else
format.html { render :new }
format.json { render json: @board.errors, status: :unprocessable_entity }
end
end
end
lists_controller.rb（整个文件）
class ListsController < ApplicationController
before_action :set_list, only: [:show, :edit, :update, :destroy]
before_action :authenticate, except: [:show]
# GET /lists
# GET /lists.json
def index
@lists = List.all
end
# GET /lists/1
# GET /lists/1.json
def show
@lists = current_user.board_id
end
# GET /lists/new
def new
@list = List.new
end
# GET /lists/1/edit
def edit
end
# POST /lists
# POST /lists.json
def create
@list = List.new(list_params)
respond_to do |format|
if @list.save
format.html { redirect_to @list, notice: 'List was successfully created.' }
format.json { render :show, status: :created, location: @list }
else
format.html { render :new }
format.json { render json: @list.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /lists/1
# PATCH/PUT /lists/1.json
def update
respond_to do |format|
if @list.update(list_params)
format.html { redirect_to @list, notice: 'List was successfully updated.' }
format.json { render :show, status: :ok, location: @list }
else
format.html { render :edit }
format.json { render json: @list.errors, status: :unprocessable_entity }
end
end
end
# DELETE /lists/1
# DELETE /lists/1.json
def destroy
@list.destroy
respond_to do |format|
format.html { redirect_to lists_url, notice: 'List was successfully destroyed.' }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_list
@list = List.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def list_params
params.require(:list).permit(:title, :board_id)
end
end
我已经阅读了几篇关于嵌套模型的SO帖子，以及Rails文档。我知道我的知识差距某处。我会很感激任何方向，因为我试图阅读其他人。问题和尝试的解决方案都失败了。
答案 0 :(得分：1)
如果您希望List对象能够访问:memberships对象的Board，请执行...
class List << ActiveRecord::Base
delegate :memberships, to: :board
删除
has_one :board, :through => :memberships, :source => :board因为那没有意义......你已经有了董事会关系而你没有会员关系可以用来建立不同的董事会关系。