Rails列表记录类似x的属性

Question

例如，我有4条账单记录。

id    = 1 
prize = 100
city  = "newyork"
id    = 2
prize = 200
city  = "NEWYORK"
id    = 3 
prize = 300
city  = "Boston"
id    = 4
prize = 400
city  = "BOSTON"

我想获得像{"Newyork" => 2 , "Boston" => 2 }

Answer 1

your_collection.group_by(&:city)