Bug #16825: JSON#generate gives invalid json string

• Status: Third Party's Issue
• Assignee: -
• Target version: -
• ruby -v: 2.6.5
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN

[definitely_not_a_bot (Definitely Not A Bot)]

Hello Guys! First of all, thank you for working on the Ruby language.

I observed a peculiarity while playing around with JSON#generate. When hash contains keys of the same word/literal but as symbol and string in the same hash, the JSON#generate creates JSON string with a duplicate key.

require 'json'

my_hash = { key: "symbol", "key" => "string" }

JSON.generate(my_hash) #=> "{\"key\":\"symbol\",\"key\":\"string\"}"

Expected:

JSON.generate(my_hash) #=> "{\"key\":\"string\"}"

I am new to ruby, so not sure if this right platform to report this observation. I do feel like the current result is the desired result but found it little odd behavior.

Please do close this issue if, it is not the right platform for the issue or it is the intended behavior.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Third Party's Issue

Interesting.

As JSON.generate converts the keys by to_s, it can be funnier.

$ ruby -rjson -e 'puts JSON.generate({"main"=>"string", :main=>"symbol", self=>"object"})'
{"main":"string","main":"symbol","main":"object"}

Anyway, https://github.com/flori/json is the upstream of the bundled json library.

[shyouhei (Shyouhei Urabe)]

Actually it is not an invalid JSON in any sense. RFC 8259 section 4 explicitly allows such duplicated names:
https://tools.ietf.org/html/rfc8259#section-4

[definitely_not_a_bot (Definitely Not A Bot)]

shyouhei (Shyouhei Urabe) wrote in #note-2:

Actually it is not an invalid JSON in any sense. RFC 8259 section 4 explicitly allows such duplicated names:
https://tools.ietf.org/html/rfc8259#section-4

I am little confused now, RFC states that

The names within an object SHOULD be unique.

But it also states that

When the names within an object are not
unique, the behavior of software that receives such an object is
unpredictable. Many implementations report the last name/value pair
only. Other implementations report an error or fail to parse

So what should be correct behaviour.