从文本文件中解析JSON

我有一个日志文件，它看起来有一个时间戳，后跟一个制表符，然后是一个JSON字符串。从文本文件中解析JSON

10/28/2014 00:04:51 {"servers":[{"id":833495,"account_id":39033,"name":"USTSMASCMSP113","host":"USTSMASCMSP113","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":28.7,"cpu_stolen":0,"disk_io":0.17,"memory":60.8,"memory_used":10444865536,"memory_total":17176723456,"fullest_disk":84.0,"fullest_disk_free":8171000000},"links":{"alert_policy":28370}},{"id":831246,"account_id":39033,"name":"USTSMASCMSP118","host":"USTSMASCMSP118","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":30.7,"cpu_stolen":0,"disk_io":2.57,"memory":54.3,"memory_used":9329180672,"memory_total":17176723456,"fullest_disk":83.1,"fullest_disk_free":8653000000},"links":{"alert_policy":28370}},{"id":833455,"account_id":39033,"name":"USTSMASCMSP119","host":"USTSMASCMSP119","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":36.3,"cpu_stolen":0,"disk_io":0.38,"memory":54.5,"memory_used":9362735104,"memory_total":17176723456,"fullest_disk":73.7,"fullest_disk_free":17912000000},"links":{"alert_policy":28370}},{"id":838342,"account_id":39033,"name":"USTSMASCMSP120","host":"USTSMASCMSP120","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":29.6,"cpu_stolen":0,"disk_io":0,"memory":55.6,"memory_used":9550430208,"memory_total":17176723456,"fullest_disk":84.9,"fullest_disk_free":10259000000},"links":{"alert_policy":28370}},{"id":833500,"account_id":39033,"name":"USTSMASCMSP121","host":"USTSMASCMSP121","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":38.9,"cpu_stolen":0,"disk_io":5.47,"memory":56.7,"memory_used":9743368192,"memory_total":17176723456,"fullest_disk":84.9,"fullest_disk_free":10288000000},"links":{"alert_policy":28370}},{"id":831221,"account_id":39033,"name":"USTSMASCMSP123","host":"USTSMASCMSP123","health_status":"orange","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":32.4,"cpu_stolen":0,"disk_io":0.42,"memory":53.8,"memory_used":9232711680,"memory_total":17176723456,"fullest_disk":87.2,"fullest_disk_free":8705000000},"links":{"alert_policy":28370}},{"id":833466,"account_id":39033,"name":"USTSMASCMSP124","host":"USTSMASCMSP124","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":25.1,"cpu_stolen":0,"disk_io":4.28,"memory":58.6,"memory_used":10065281024,"memory_total":17176723456,"fullest_disk":74.2,"fullest_disk_free":19387000000},"links":{"alert_policy":28370}},{"id":838346,"account_id":39033,"name":"USTSMASCMSP125","host":"USTSMASCMSP125","health_status":"orange","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":32.2,"cpu_stolen":0,"disk_io":0.13,"memory":56.5,"memory_used":9703522304,"memory_total":17176723456,"fullest_disk":89.1,"fullest_disk_free":7443000000},"links":{"alert_policy":28370}},{"id":833504,"account_id":39033,"name":"USTSMASCMSP126","host":"USTSMASCMSP126","health_status":"orange","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":29.6,"cpu_stolen":0,"disk_io":0,"memory":56.9,"memory_used":9776922624,"memory_total":17176723456,"fullest_disk":85.7,"fullest_disk_free":9761000000},"links":{"alert_policy":28370}},{"id":831212,"account_id":39033,"name":"USTSMASCMSP127","host":"USTSMASCMSP127","health_status":"orange","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":30.5,"cpu_stolen":0,"disk_io":0,"memory":50.9,"memory_used":8735686656,"memory_total":17176723456,"fullest_disk":85.0,"fullest_disk_free":10222000000},"links":{"alert_policy":28370}},{"id":833510,"account_id":39033,"name":"USTSMASCMSP128","host":"USTSMASCMSP128","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":26.8,"cpu_stolen":0,"disk_io":0,"memory":57.8,"memory_used":9936306176,"memory_total":17176723456,"fullest_disk":79.7,"fullest_disk_free":10393000000},"links":{"alert_policy":28370}},{"id":833473,"account_id":39033,"name":"USTSMASCMSP129","host":"USTSMASCMSP129","health_status":"orange","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":31.9,"cpu_stolen":0,"disk_io":0.17,"memory":56.4,"memory_used":9693036544,"memory_total":17176723456,"fullest_disk":86.7,"fullest_disk_free":9095000000},"links":{"alert_policy":28370}},{"id":3922351,"account_id":39033,"name":"USTSMASCMSP136","host":"USTSMASCMSP136","health_status":"orange","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":16.2,"cpu_stolen":0,"disk_io":0.28,"memory":13.3,"memory_used":4552916992,"memory_total":34356592640,"fullest_disk":73.3,"fullest_disk_free":56043000000},"links":{"alert_policy":28369}},{"id":831184,"account_id":39033,"name":"USTSMASCMSP144","host":"USTSMASCMSP144","health_status":"orange","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summ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031,"account_id":39033,"name":"USTSMASCMSP205","host":"USTSMASCMSP205","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":27.8,"cpu_stolen":0,"disk_io":0,"memory":24.9,"memory_used":4285530112,"memory_total":17176723456,"fullest_disk":68.8,"fullest_disk_free":16376000000},"links":{"alert_policy":28370}},{"id":832024,"account_id":39033,"name":"USTSMASCMSP206","host":"USTSMASCMSP206","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":30.2,"cpu_stolen":0,"disk_io":0,"memory":26.5,"memory_used":4548722688,"memory_total":17176723456,"fullest_disk":67.2,"fullest_disk_free":17181000000},"links":{"alert_policy":28370}},{"id":831202,"account_id":39033,"name":"USTSMASCMSP207","host":"USTSMASCMSP207","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":23.9,"cpu_stolen":0,"disk_io":0,"memory":25.6,"memory_used":4394582016,"memory_total":17176723456,"fullest_disk":67.3,"fullest_disk_free":17146000000},"links":{"alert_policy":28370}},{"id":3979556,"account_id":39033,"name":"USTSMASCMSP227","host":"USTSMASCMSP227","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":8.25,"cpu_stolen":0,"disk_io":5.96,"memory":18.1,"memory_used":3116367872,"memory_total":17174626304,"fullest_disk":65.1,"fullest_disk_free":18301000000},"links":{"alert_policy":28369}},{"id":3965125,"account_id":39033,"name":"USTSMASCMSP247","host":"USTSMASCMSP247","health_status":"green","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":18.2,"cpu_stolen":0,"disk_io":34.0,"memory":32.3,"memory_used":5543821312,"memory_total":17174626304,"fullest_disk":59.9,"fullest_disk_free":28765000000},"links":{"alert_policy":28369}},{"id":3965022,"account_id":39033,"name":"USTSMASCMSP248","host":"USTSMASCMSP248","health_status":"orange","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":43.9,"cpu_stolen":0,"disk_io":8.61,"memory":28.1,"memory_used":4821352448,"memory_total":17143169024,"fullest_disk":86.5,"fullest_disk_free":9645000000},"links":{"alert_policy":28369}},{"id":3851100,"account_id":39033,"name":"ustsmvscmsp888","host":"ustsmvscmsp888","health_status":"orange","reporting":true,"last_reported_at":"2014-10-28T04:04:17+00:00","summary":{"cpu":19.7,"cpu_stolen":0,"disk_io":0,"memory":42.9,"memory_used":1841299456,"memory_total":4293918720,"fullest_disk":72.9,"fullest_disk_free":14243000000},"links":{"alert_policy":28369}}],"links":{"server.alert_policy":"/v2/alert_policies/{alert_policy_id}"}}

我有读取输入文件的代码，我试图从字符串中获取值，如下所示。

require 'json' 

input = File.open("input.txt", 'r') 

input.each do |line| 
    line = line.split("\t") 
    my_json = line[1].to_json 
    puts my_json["cpu"] 
end

最终的结果看起来是这样的：

C:\>ruby test.rb 
cpu

我不能完全肯定，如果字符串本身的格式不正确，或者如果我不上的值调用正确。

来源

2014-10-30 Todd J.

运行这段代码里面控制台，并检查返回，但我敢肯定你不能叫

my_json["cpu"]

您需要调用类似：

my_json["servers"].first["cpu"]

来源

2014-10-30 13:26:11

my_json = line[1].to_json

威尔获取一个对象并将其转换为JSON，而不是将现有的JSON字符串解析为一个ruby对象。您将结束JSON字符串中的转义字符串。

你需要像

my_json = JSON.parse(line[1])

您可以验证这一点已经通过输出my_json到stdout工作正常：

$stdout << my_json.class.name

你应该有哈希或Openstruct的一个实例。

来源

2014-10-30 13:30:22 mcfinnigan

这是这个和@ paulo-henrique发布的答案的组合 – 2014-10-30 13:39:34

考虑一下：

require 'json' 

line = '10/28/2014 00:04:51 {"servers":[{"id":833495,"account_id":39033}]}' 
JSON[line[/\{.+}/]] 
# => {"servers"=>[{"id"=>833495, "account_id"=>39033}]}

这意味着你可以减少你的解析代码是这样的：

File.foreach("input.txt") do |line| 
    data = JSON[line[/\{.+}/]] 
    # do something with the data 
end

正则表达式是贪婪的，所以/\{.+}/将开始在第一{和期待，直到它找到最后的}，并返回起始和结束括号以及其间的所有内容。

JSON []方法足够聪明，知道如果它的参数是一个字符串，它应该尝试解析它并返回一个Ruby数组或哈希。如果该参数是一个Array或Hash，它将序列化它。

注意：这是不必要的，绝对不希望包含像您这样的大数据样本。将其降低到证明问题所需的最低限度。

来源

2014-10-30 15:32:51

从文本文件中解析JSON

回答

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