@order.save的未定義方法`item_id'

我正在創建一個帶有關系資料庫的 rails 應用程式，當我嘗試將出現 NoMethodError 的訂單保存到我傳遞給 order.new 的字串時，我是 rails 新手，可能不完全了解如何處理記錄。但是除錯器不能告訴我在哪里搜索錯誤。

控制器

class OrdersController

  def create
    #render plain: params
    a = {amount: params[:amount], user_id: current_user.id, id: 1}
    @order = Order.new a

    a = {quantity: params[:quantity], item_id: params[:item], order_id: 1}
    @order_description = OrderDescription.new a
    @order.save
    @order_description.save
  end

錯誤

undefined method `item_id' for #<Order id: 1, amount: 2222, created_at: nil, updated_at: nil, user_id: 19>

D b

  create_table "items", force: :cascade do |t|
    t.string "name"
    t.string "description"
    t.integer "price"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
  end

  create_table "order_descriptions", force: :cascade do |t|
    t.integer "quantity"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.bigint "item_id", null: false
    t.bigint "order_id", null: false
    t.index ["item_id"], name: "index_order_descriptions_on_item_id"
    t.index ["order_id"], name: "index_order_descriptions_on_order_id"
  end

  create_table "orders", force: :cascade do |t|
    t.integer "amount"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.bigint "user_id", null: false
    t.index ["user_id"], name: "index_orders_on_user_id"
  end

  create_table "users", force: :cascade do |t|
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    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.string "last_name"
    t.string "first_name"
    t.boolean "admin", default: false
    t.index ["email"], name: "index_users_on_email", unique: true
    t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
  end

  add_foreign_key "order_descriptions", "items"
  add_foreign_key "order_descriptions", "orders"
  add_foreign_key "orders", "users"

我試圖洗掉 ruby?? 模型中的關系，但沒有幫助。無論我傳遞給它的資料如何，都會發生此錯誤。

真解

在檔案夾 test/fixters 中，我發現了一個名為 order.yml 的檔案，其中包含 item_id 欄位（天知道它是如何出現在那里的）并且由于這些欄位 order.save 沒有通過驗證測驗。

uj5u.com熱心網友回復：

您似乎正在嘗試建立has_many through:關聯。whereorder_descriptions作為訂單的行專案。

class Order < ApplicationRecord
  belongs_to :user
  has_many :order_descriptions
  has_many :items, through: :order_descriptions
end

# very vague name - you could do better
class OrderDescription < ApplicationRecord
  belongs_to :item
  belongs_to :order
end

class Item < ApplicationRecord
  has_many :order_descriptions
  has_many :orders, through: :order_descriptions
end

如果您想創建一個經典的訂單表格，您可以在其中創建多行訂單，您可以使用accepts_nested_attributes：

class Order < ApplicationRecord
  has_many :order_descriptions
  has_many :items, through: :order_descriptions
  accepts_nested_attributes_for :order_descriptions, reject_if: :all_blank?
end

這使您可以傳遞一組屬性（散列）以同時創建父記錄和子記錄：

Order.create(
  user: User.first,
  order_descriptions_attributes: [
    { item_id: 1, quantity: 10 },
    { item_id: 2, quantity: 20 }
  ]
)

您可以使用以下形式處理此問題fields_for：

<%= form_with(model: @order) do |form| %>
  <%= form.fields_for(:order_descriptions) do |ff| %>
    <div class="field">
      <%= ff.label :item_id %>
      <%= ff.collection_select :item_id, @items, :id, :name %>
    </div>
    <div >
      <%= ff.label :quantity %>
      <%= ff.number_field :quantity, step: 1 %>
    </div>
  <% end %>
<% end %>

在您的控制器中：

class OrdersController
  before_action :set_order, only: [:show, :edit, :update, :destroy]

  def show
  end

  def new
    @order = Order.new
    @items = Item.all
    5.times { @order.order_descriptions.new } 
  end

  def create
    @order = Order.new(order_params) do |order|
      order.user = current_user
    end
    if @order.save
      redirect_to @order 
    else
      @items = Item.all
      5.times { @order.order_descriptions.new } 
      render :new
    end
  end

  private

  def set_order
     @order = Order.find(params[:id])
  end
  
  def order_params
    params.require(:order)
          .permit(
            order_descriptions_attributes: [:id, :item_id, :quantity]
          )
  end
end

order_descriptions_attributes: [:item_id, :quantity]允許使用鍵為:id,:item_id和的散列陣列:quantity。

In terms of user experience its really far from ideal though - and for your typical web shop you'll want to create the order (or in other terms cart) upfront and then setup a nested route where users add line items to the order.

標籤：红宝石轨道 红宝石 数据库 无方法错误

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