ruby:从嵌套的json中提取字段

问题描述：

我试图自学红宝石并解决工作中的问题.我的最终目标是从API提取JSON响应中的许多字段中的三个，然后处理并转储到CSV以供执行人员报告.

I am trying to teach myself ruby and solve a problem at work. My ultimate goal is to extract out three of the many fields in JSON response from an API, manipulate and dump to CSV for executive reporting.

JSON的结构为:

{
  "status": 200,
  "data": {
    "total": 251,
    "alerts": [
      {
        "dataPoint": "x",
        "ackedBy": "x",
        "dataSourceInstance": "x",
        "dataSource": "x",
        "host": "x",
        "endOn": 0,
        "ackedOn": 1385085190,
        "dataSourceInstanceId": 588384,
        "hostId": 935,
        "type": "alert",
        "dataSourceId": 694,
        "ackedOnLocal": "2013-11-21 17:53:10 PST",
        "id": 6170384,
        "startOn": 1385084917,
        "thresholds": "!= 1 1 1",
        "endOnLocal": "",
        "level": "error",
        "ackComment": "x",
        "value": "No Data",
        "hostDataSourceId": 211986,
        "acked": true,
        "hostGroups": [{
          "alertEnable": true,
          "createdOn": 1362084592,
          "id": 21,
          "parentId": 78,
          "description": "",
          "appliesTo": "",
          "name": "2600hz",
          "fullPath": "x"
        }],
        "startOnLocal": "2013-11-21 17:48:37 PST"
      },

具体来说，我想提取dataPoint，startOn，ackedOn.

To be specific I want to extract out dataPoint,startOn,ackedOn.

我想我需要首先提取总价值，所以我知道我有多少警报.这将帮助我遍历警报实例.

I am thinking I need to extract the total value first, so I know how many alerts I have. That will help me loop through the alert instances.

*url = "https://xyz"
uri = URI(url)
http = Net::HTTP.new(uri.host, 443)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE
req = Net::HTTP::Get.new(uri.request_uri)
response = http.request(req)

# Make sure we had a proper web response
if response.code == '200' then

# Set up that the total is two levels deep in the json
path = JsonPath.new('$.total')

# Extract out total field into variable
totalAlerts = path.on(response)

# Print hash to confirm value
pp totalAlerts

end*

我被困于试图只提取总数.输出未显示任何内容:

I am stuck trying to just extract out the total. Output shows nothing:

sudo ruby alerts.rb
[]

有更好的方法吗?

答

尝试一下:

# just for demonstration, you would probably do json = JSON.parse(response)
json = {
  "status": 200,
  "data": {
    "total": 251,
    "alerts": [
      {
        "dataPoint": "x",
        "ackedBy": "x",
        ...

仅计总数:

total = json['data']['total']

对于您询问的其他值:

json['data']['alerts'].each do |alerts|
  # do whatever you want with these...
  alerts['dataPoint']
  alerts['startOn']
  alerts['ackedOn']

现在的问题是，您要如何处理结果?您想将它们收集到新的哈希中吗? json['data']['alerts']是一个数组，因此您必须决定如何收集它们.您可以这样做:

Now the question is, what do you want to do with the results? Do you want to collect them into a new hash? The json['data']['alerts'] is an array so you have to decide how you want to collect them. You could do:

collected_alerts = { 'dataPoints' => [], 'startOns' => [], 'ackedOns' => [] }
json['data']['alerts'].each do |alerts|
  collected_alerts['dataPoints'] << alerts['dataPoint']
  collected_alerts['startOns'] << alerts['startOn']
  collected_alerts['ackedOns'] << alerts['ackedOn']
end

现在您可以在collected_alerts

ruby:从嵌套的json中提取字段

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