在rails中包含没有关系的表

Question

我有控制器，我正在加载所有发票与以下代码。

  def index
    @invoices = Invoice.includes(:customer).all
  end

我有以下发票和客户型号

class Invoice < ApplicationRecord
  belongs_to :customer

  delegate :name,
           :street,
           :city,
           :state,
           :zip_code,
           to: :customer,
           prefix: true
end

class Customer < ApplicationRecord
  has_one :address
  has_many :invoices

  delegate :street, :city, :state, :zip_code, to: :address
end

现在在我看来，我有以下代码

%tr
  = render partial: "row", locals: { data: invoice.id }
  = render partial: "row", locals: { data: invoice.customer_name }
  = render partial: "row", locals: { data: invoice.customer_street }
  = render partial: "row", locals: { data: invoice.customer_city }
  = render partial: "row", locals: { data: invoice.customer_state }
  = render partial: "row", locals: { data: invoice.customer_zip_code }

由于我使用的是地址，它正在执行N+1，我在下面的行中包含了customer

@invoices = Invoice.includes(:customer).all

但是我如何在其中添加地址，所以不会出现地址的N+1查询。现在，我已经修复了客户，只有两个查询即将到来，但我也需要在其中添加地址。

Answer 1

@invoices = Invoice.includes(customer: :address).all

给每个发票包括客户和每个客户包括地址。