ruby - Ruby / Rails：如何显示每年和每月的总和值？

Question

我有一个名为 Receipt 的模型，它具有以下内容：

• date_of_purchase - 日期时间
• total_value - 浮动

我有一个包含许多收据的数据库，例如：

收据 1

• date_of_purchase = 2012-01-23
• 总价值 = 6

收据 2

• date_of_purchase = 2012-01-04
• 总价值 = 70

收据 3

• date_of_purchase = 2013-02-14
• 总价值 = 1.23

收据 4

• date_of_purchase = 2013-02-06
• 总价值 = 90.34

...

收据 123

• date_of_purchase = 2013-08-05
• 总价值 = 43.69

我如何显示这样的东西：

{2012=>{1=>76}, 2013=>{2=>92.23, 3=> 34.43, ...}}

?

Answer 1

以下应该工作

receipts = Receipt.find_by_sql("SELECT MONTH(date_of_purchase) AS month, 
                       YEAR(date_of_purchase) AS year, SUM(total_value) as sum
                       FROM receipts GROUP BY year, month")

receipts_hash = {}
receipts.each do |receipt|
  receipts_hash[receipt.year] = {} unless receipts_hash[receipt.year]
  receipts_hash[receipt.year][receipt.month] = receipt.sum
end