Ruby

Question

我有一个包含数万个订单的对象。对象看起来像这样：

[#<Order id: 4304, order_code: 'AB11', manufacturer_id: 24, ...>, 
 #<Order id: 7664, order_code: 'AB13', manufacturer_id: 24, ...>, 
 #<Order id: 4164, order_code: 'AB255', manufacturer_id: 724, ...>, 
 #<Order id: 7671, order_code: 'AX88', manufacturer_id: 855, ...>,
...]

现在，我想要得到的东西 - 我想要一个看起来像这样（或类似的东西）的对象：

[ 
  {manufacturer_id: 24, orders: [{id: 4304, order_code: 'AB11'}, {id: 7664, order_code: 'AB13'}]},
  {manufacturer_id: 724, orders: [{id: 4164, order_code: 'AB255'}]},
  ...
]

从给定的 Order 对象中提取信息的最有效方法是什么？这将在一天内完成几次。

谢谢。

Answer 1

你可以这样做

list.group_by(&:manufacturer_id).map do |k,v| 
  { 
    manufacturer_id: k, 
    orders: v.collect{ |o| {id: o.id, order_code: o.order_code }}  
  }      
end

输出如下所示

=> [{:manufacturer_id=>24, :orders=>[{:id=>4304, :order_code=>"AB11"}, {:id=>7664, :order_code=>"AB13"}]}, {:manufacturer_id=>724, :orders=>[{:id=>4164, :order_code=>"AB255"}]}, {:manufacturer_id=>855, :orders=>[{:id=>7671, :order_code=>"AX88"}]}]

Answer 2

我最终会成为一些主持人，比如 PORO（普通的旧 ruby 对象）


class OrderPresenter
  attr_reader :records

  def initialize(records)
    @records = records
  end

  def as_json
    records.group_by(&:manufacturer_id).map do |k, v| 
      { 
        manufacturer_id: k, 
        orders: v.collect { |o| {id: o.id, order_code: o.order_code } }  
      }      
    end  
  end
end

而且我不认为你一次需要它们？所以你可以做一些类似部分加载的事情，而不是炸毁你所有的内存

records.each_slice(1000) do |group|
  data = OrderPresenter.new(records).as_json
  # perform something on that data
end

Ruby - 如何有效地从对象中获取和分组某些信息？

Ruby - how to effectively fetch and group certain information from an object?

postgresql

model

ruby-on-rails

object