Question

我正在尝试在rails上的ruby中实现购物清单。我在数据库中创建了两个表，products和shopping_list。我已经为product_list提供了产品的外键引用product.shopping_list_id。

我正在尝试在轨道上的红宝石中找到total products中的shopping list但我收到错误。

我的创建商店架构如下： -

class CreateShopSchema < ActiveRecord::Migration
  def up

        # --------------------

        # Table Name: shopping_list
        # --------------------
        # Note: This is the base table that has details about an account.
        # ---------------------------------------------------------------

    create_table :shopping_lists do |t|
            t.string     :id, :null => false
            t.string     :shopping_list_name
            t.string     :shopping_list_status, :default => 'OPEN'          
            t.string     :total_items, :default => 0
            t.timestamps
    end

        # --------------------
        # Table Name: products
        # --------------------
        # Note: This is the base table that has details about an account.
        # ---------------------------------------------------------------

    create_table :products do |t|
            t.references :shopping_list, :null => false
            t.string     :product_name,  :default => 'null'
            t.string     :product_category
            t.integer    :quantity          
            t.string     :status, :default => 'OPEN' 
    end


  end

  def down
    drop_table :products
    drop_table :shopping_lists
  end

end

我的shopping_list表格如下： -

CREATE TABLE shopping_lists
(
  id serial NOT NULL,
  shopping_list_name character varying(255),
  shopping_list_status character varying(255) DEFAULT 'OPEN'::character varying,
  total_items character varying(255) DEFAULT 0,
  created_at timestamp without time zone NOT NULL,
  updated_at timestamp without time zone NOT NULL,
  deleted integer NOT NULL DEFAULT 0,
  CONSTRAINT shopping_lists_pkey PRIMARY KEY (id)
)

我的产品表如下： -

CREATE TABLE products
(
  id serial NOT NULL,
  shopping_list_id integer NOT NULL,
  product_name character varying(255) DEFAULT 'null'::character varying,
  product_category character varying(255),
  quantity integer,
  status character varying(255) DEFAULT 'OPEN'::character varying,
  deleted integer NOT NULL DEFAULT 0,
  CONSTRAINT products_pkey PRIMARY KEY (id)
)

我的产品控制器如下： -

class ProductsController < ApplicationController
  # GET /products
  # GET /products.json
  def index
  @products = Product.all
   # @products = Product.includes(:shopping_list_id)

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @products }
    end
  end  

  # GET /products/1
  # GET /products/1.json
  def show
   @product = Product.find(params[:id])
   #product = Product.includes(:shopping_list_id)
   #@product = Product.joins(:shopping_list_id)


    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @product }
    end
  end

  # GET /products/new
  # GET /products/new.json
  def new
    @product = Product.new

    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @product }
    end
  end

  # GET /products/1/edit
  def edit
    @product = Product.find(params[:id])
  end

  # POST /products
  # POST /products.json
  def create
    @product = Product.new(params[:product])

    respond_to do |format|
      if @product.save
        format.html { redirect_to @product, notice: 'Product was successfully created.' }
        format.json { render json: @product, status: :created, location: @product }
      else
        format.html { render action: "new" }
        format.json { render json: @product.errors, status: :unprocessable_entity }
      end
    end
  end

  # PUT /products/1
  # PUT /products/1.json
  def update
    @product = Product.find(params[:id])

    respond_to do |format|
      if @product.update_attributes(params[:product])
        format.html { redirect_to @product, notice: 'Product was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @product.errors, status: :unprocessable_entity }
      end
    end
  end


  # DELETE /products/1
  # DELETE /products/1.json


def delete
    @product = Product.find(params[:id])
    @product.deleted = 1
    @product.save

    respond_to do |format|
      format.html { redirect_to products_url }
      format.json { render :json => { :success => true } }
    end
  end

  def list
   @products = Product.find(:all,
                 :order => "id asc")
  # @products = Product.includes(:shopping_list_id)



    respond_to do |format|
      format.html { render :action => 'list' }
      format.json { render :json => @accounts.to_json }
    end       
  end

 end

当我尝试通过前端在数据库中添加新产品时，将填充产品表，但shopping_list中的数量（总项数）未在数据库中更新。

我想以这样的方式实施，以便我可以获得特定购物清单的产品数量

任何人都可以帮我实现这个

Answer 1

好的，为什么不考虑将应用程序设置为以下内容：

<强> Product.rb

belongs_to :category 
belongs_to :shopping_list


def total_price
    product.price * quantity
  end

Category.rb

has_many :products

Line_item

belongs_to :product 
belongs_to :shopping_list 
belongs_to :order --> will let you finish the rest

<强> shopping_list.rb

has_many :line_items

您的订单表将包含quantity。要获得订单中的quantity，您可以执行以下操作：

def quantity
    line_items.to_a.sum { |quant| quant.quantity }
  end

将上述内容放入您的产品型号中意味着您可以使用product/index.html.erb - ＆gt; <%= order.quantity %>

在rails 3.2的数据库中实现数据更新时出错

1 个答案: