ruby-on-rails - Ruby 遍历日期

Question

你好，我有这样的 Schedules 表；

<ActiveRecord::Relation [#<Schedule id: 427, date: "2016-06-15", notes: nil, price: "350", promo: "", status: "available", boat_id: 45, created_at: "2016-06-09 19:43:15", updated_at: "2016-06-09 19:43:15">, #<Schedule id: 428, date: "2016-06-16", notes: nil, price: "350", promo: "", status: "available", boat_id: 45, created_at: "2016-06-09 19:43:15", updated_at: "2016-06-09 19:43:15">, #<Schedule id: 429, date: "2016-06-17", notes: nil, price: "350", promo: "", status: "available", boat_id: 45, created_at: "2016-06-09 19:43:15", updated_at: "2016-06-09 19:43:15">, #<Schedule id: 430, date: "2016-06-22", notes: "", price: "253", promo: "", status: "available", boat_id: 3, created_at: "2016-06-14 09:23:55", updated_at: "2016-06-14 09:23:55">, #<Schedule id: 431, date: "2016-06-23", notes: "", price: "253", promo: "", status: "available", boat_id: 3, created_at: "2016-06-14 09:23:55", updated_at: "2016-06-14 09:23:55">]

和用户输入“从”和“到”日期。假设我有这样的变量

a = "2016-06-16".in_time_zone('UTC')
b = "2016-06-19".in_time_zone('UTC')

我想在这些日期(a 和 b)之间循环 Schedule 表并获得价格总和..

我想到了一个这样的解决方案，我可以说；

a = "2016-06-16".in_time_zone('UTC')
b = "2016-06-19".in_time_zone('UTC')
schedules = Schedule.all
price = 0

dates = []
while a < b do
 dates << a
 a += 1.day
end

然后;

dates.each do |date|
  schedules.each do |schedule|
    if (date == schedule.in_time_zone('UTC'))
      price += schedule.price.to_i
    end
  end
end

但不知道这是否是最方便的方法。

Answer 1

为什么不利用 DB native 实现。您可以在 SQL 中完成。

date_from = "2016-06-16".in_time_zone('UTC')
date_to   = "2016-06-19".in_time_zone('UTC')

Schedule
  .where(date: date_from..date_to) # sql BETWEEN operator
  .sum("price") # SQL aggregate function.