使用Ruby按值过滤JSON数组

Question

我有一个看起来像这样的JSON数组。

[
 {"name":"Idaho","state":{"id":1,"name":"A"}},
 {"name":"Wyoming","state":{"id":1,"name":"A"}},
 {"name":"Montana","state":{"id":2,"name":"B"}},
 {"name":"South Dakota","state":{"id":1,"name":"B"}}
]

我如何使用Ruby仅显示A的值？

我不认为sort_by会成为答案，因为我在下面的内容只是按字母顺序对它们进行排序。我想完全排除B的所有结果。

.sort_by { |a| [a.state.name] }

在.rb文件中执行此操作的最有效方法是什么？

---

我解决了自己的问题。这就是我实现我想要的目标。

.select { |a| a.state.name == "A" }

Answer 1

require 'json'

json = <<'JSON_STRING'
[
 {"name":"Idaho","state":{"id":1,"name":"A"}},
 {"name":"Wyoming","state":{"id":1,"name":"A"}},
 {"name":"Montana","state":{"id":2,"name":"B"}},
 {"name":"South Dakota","state":{"id":1,"name":"B"}}
]
JSON_STRING

data = JSON.parse json

data.map(&:values).select { |state, values| values["name"] == ?A }
#=> [["Idaho", {"id"=>1, "name"=>"A"}], ["Wyoming", {"id"=>1, "name"=>"A"}]]

data.map(&:values).select { |state, values| values["name"] == ?A }.map(&:first)
#=> ["Idaho", "Wyoming"]

Answer 2

require 'json'

arr = JSON.parse <<END_OF_JSON
[
 {"name":"Idaho","state":{"id":1,"name":"A"}},
 {"name":"Wyoming","state":{"id":1,"name":"A"}},
 {"name":"Montana","state":{"id":2,"name":"B"}},
 {"name":"South Dakota","state":{"id":1,"name":"B"}}
]
END_OF_JSON

results = []

arr.each do |hash|
  results << hash["name"] if hash["state"]["name"] == "A"
end

p results

--output:--
["Idaho", "Wyoming"]

Answer 3

不正确：

.select { |a| a.state.name == "A" }

正确的方法：

.select { |a| a['state']['name'] == 'A' }