Question

我最近将一张表分成了三个单独的表格，现在无法将它们组合成一个列表。

我有一个场地 - 有很多订单 - 有很多项目

试图列出场地的所有订单和附带信息：

app.rb

get "/:venue/orders" do
  @venue = Venue.find_by_handle(params[:venue])
  @orders = Order.joins(:venue).where(:venues => {:handle => @venue.handle})
  @items = Item.joins(:order).where(:orders => {:id => @orders.id})
  erb :"venue/index"
end

地点/ index.erb

<% @orders.each do |order| %>
  <h3>Order <%= order.id %></h3>
  <h4><%= @customer.email %></h4>
  <% @items.each do |item| %>
    <h5><%= item.quantity %> x <%= item.item %></h5>
  <% end %>
<% end %>

models.rb

class Order < ActiveRecord::Base
  belongs_to :venue
  belongs_to :customer

  has_many :items

  validates :venue_id, presence: true
end

class Item < ActiveRecord::Base
  belongs_to :order

  validates :order_id, :presence => true
  validates :quantity, :presence => true
  validates :item, :presence => true
end

class Customer < ActiveRecord::Base
  has_many :orders

  validates :email, :presence => true
end

class Venue < ActiveRecord::Base
  has_many :customers, :through => :orders
  has_many :orders

  validates :name, :presence => true
  validates :handle, :presence => true, :uniqueness => true
end

我收到了＃id; id＆＃39;的NoMethodError并理解，因为我没有看特定的订单。如何查询必要的项目？

Answer 1

这就是诀窍：

@venue = Venue.includes({:orders => [:customer, :items]}).find_by_handle(params[:venue])

然后，在您看来：

<% @venue.orders.each do |order| %>
  <h3>Order <%= order.id %></h3>
  <h4><%= order.customer.email %></h4>
  <% order.items.each do |item| %>
    <h5><%= item.quantity %> x <%= item.item %></h5>
  <% end %>
<% end %>

与ActiveRecord和Sinatra的多维JOIN

1 个答案: