nil.to_json 无法解析回 nil? [英] nil.to_json cannot be parsed back to nil?

问题描述

此代码段引发异常:

x = nil
jsoned = x.to_json
puts 'x.to_json=' + jsoned.inspect
puts 'back=' + JSON.parse(jsoned).inspect

C:/ruby/lib/ruby/1.9.1/json/common.rb:146:in `parse': 706: unexpected token at 'null'      (JSON::ParserError)
x.to_json="null"
from C:/ruby/lib/ruby/1.9.1/json/common.rb:146:in `parse'
from C:/dev/prototyping/appoxy_app_engine/test/temp.rb:10:in `<top (required)>'
from -e:1:in `load'
from -e:1:in `<main>'

这是预期的行为吗?我认为这应该有效吗?

Is that expected behavior? I would think this should work?

推荐答案

该问题不在于 nil.就是 to_json 在像 nil 这样简单的东西或单个字符串上不会产生完整的 JSON 表示.

The problem is not specifically with nil. It's that to_json on a simple thing like nil or a single string doesn't produce a full JSON representation.

例如类似 JSON.parse("hello".to_json) 会产生类似的结果

e.g. something like JSON.parse("hello".to_json) would yield similar results

如果我们有一个带有 nil 的 Hash 作为其值之一，它将正确编码和解码:

If we have a Hash with nil for one of its values it will encode and decode correctly:

>> h = {"name"=>"Mike", "info"=>nil}
=> {"name"=>"Mike", "info"=>nil}
>> h.to_json
=> "{\"name\":\"Mike\",\"info\":null}"
>> JSON.parse(h.to_json)
=> {"name"=>"Mike", "info"=>nil}

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