如何将红宝石散列对象转换为JSON？ [英] How to convert a ruby hash object to JSON?

问题描述

如何将红宝石哈希对象转换为JSON？所以我在下面试着这个例子&它不工作？

How to convert a ruby hash object to JSON? So I am trying this example below & it doesn't work?

我在看RubyDoc，显然 Hash 对象没有 to_json 方法。但是我在博客上看到Rails支持 active_record.to_json 并且还支持 hash＃to_json 。我可以理解 ActiveRecord 是一个Rails对象，但是 Hash 不是Rails原生的，它是一个纯Ruby对象。所以在Rails中你可以做一个 hash.to_json ，但不能在纯Ruby中使用

I was looking at the RubyDoc and obviously Hash object doesn't have a to_json method. But I am reading on blogs that Rails supports active_record.to_json and also supports hash#to_json. I can understand ActiveRecord is a Rails object, but Hash is not native to Rails, it's a pure Ruby object. So in Rails you can do a hash.to_json, but not in pure Ruby??

car = {:make => "bmw", :year => "2003"}
car.to_json

推荐答案

Ruby的众多优点之一是可以使用自己的方法扩展现有的类。这就是所谓的重开班或猴子补丁（后者的含义是但是）。

One of the numerous niceties of Ruby is the possibility to extend existing classes with your own methods. That's called "class reopening" or monkey-patching (the meaning of the latter can vary, though).

所以，看看这里：

So, take a look here:

car = {:make => "bmw", :year => "2003"}
# => {:make=>"bmw", :year=>"2003"}
car.to_json
# NoMethodError: undefined method `to_json' for {:make=>"bmw", :year=>"2003"}:Hash
#   from (irb):11
#   from /usr/bin/irb:12:in `<main>'
require 'json'
# => true
car.to_json
# => "{"make":"bmw","year":"2003"}"

可以看到，需要 json 魔法地将方法 to_json 添加到我们的哈希。

As you can see, requiring json has magically brought method to_json to our Hash.

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