为什么Ruby无法解析本地JSON文件? [英] Why can Ruby not parse local JSON file?

问题描述

我在此处有一个相关问题，但我要发布另一个问题问题集中在问题的特定部分.

I have a related question here, but I'm posting another question to focus on a specific part of the problem.

目标:将脚本添加到我的Ruby应用中，该应用可以读取本地JSON文件，将其解析为Ruby哈希，然后访问其中的属性.

Goal: Add script to my Ruby app which can read a local JSON file, parse it to a Ruby hash, and access the properties within it.

系统:CentOS 7

System: CentOS 7

文件:本地保存的/tmp/valid.json 文件:

File: Locally saved /tmp/valid.json file:

{
  "firstName": "John",
  "lastName": "Smith",
  "isAlive": true,
  "age": 27,
  "address": {
    "streetAddress": "21 2nd Street",
    "city": "New York",
    "state": "NY",
    "postalCode": "10021-3100"
  },
  "phoneNumbers": [
    {
      "type": "home",
      "number": "212 555-1234"
    },
    {
      "type": "office",
      "number": "646 555-4567"
    }
  ],
  "children": [],
  "spouse": null
}

(该对象是从 Wikipedia上有关JSON的文章借来的，目的是确保我的问题不是无效的JSON.)

(That object borrowed from Wikipedia's article on JSON in an attempt to make sure that my problem isn't invalid JSON.)

代码:

require 'json'
data = File.read("/tmp/valid.json")
$evm.log(:info, data) #writes to log file, where I can see content of my JSON file
$evm.log(:info, "is data a hash ? ")
$evm.log(:info, data.is_a?(Hash).to_s) # prints false
$evm.log(:info, "is data a string? ")
$evm.log(:info, data.is_a?(String).to_s) # prints true
$evm.log(:info, "can I parse data?")
valid_ob = JSON.parse(data)
$evm.log(:info, "just parsed it, now print it")
$evm.log(:info, valid_ob)

最后一行打印:

NoMethodError: undefined method `gsub' for #<Hash:0x0000000020951f
a8>

为什么Ruby无法解析此字符串?

Why can't Ruby parse this string?

推荐答案

问题在于您分配给 $ evm 的任何内容.错误消息:

The problem is something in whatever you have assigned to $evm. The error message:

NoMethodError: undefined method `gsub' for #<Hash:>

表明您打电话时

$evm.log(:info, valid_ob)

log 方法正在尝试在 valid_ob 上调用 gsub . log 最有可能只接受字符串，并且不对接收到的对象进行类型检查.

the log method is attempting to call gsub on valid_ob. Most likely, log is meant to accept only strings and does no type checking on the object it receives.

如果您需要一种简单的交互式方式来运行此Ruby代码而不使用此 $ evm 对象，只需在控制台中运行 irb 并开始输入您的Ruby代码用于解析JSON数据:

If you need a simple, interactive way to run this Ruby code without using this $evm object, just run irb in your console and start typing in your Ruby code for parsing the JSON data:

require 'json'
 => true
data = File.read('/tmp/valid.json')
data.class
 => String
hash = JSON.parse(data)
hash.class
 => Hash
hash
 => {"firstName"=>"John", "lastName"=>"Smith", "isAlive"=>true, "age"=>27, "address"=>{"streetAddress"=>"21 2nd Street", "city"=>"New York", "state"=>"NY", "postalCode"=>"10021-3100"}, "phoneNumbers"=>[{"type"=>"home", "number"=>"212 555-1234"}, {"type"=>"office", "number"=>"646 555-4567"}], "children"=>[], "spouse"=>nil}

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