How I can parse JSON file by pure Ruby code without gem

Question

I Have tried many ways and googled but everywhere i getting same way out, use json gem to parse a JSON file.

JSON.parse(string)

And couple of links are also using same stackoverflow Link

I wanted to achieve it by pure Ruby code without using any gem or rails help.

Please have a look on a link [here](https://stackoverflow.com/a/11430924/5922155) — Asmita, Aug 29 '17 at 17:19
@asmitakalena I have already attached a link like that though thanks for prompt reply — John Ross, Aug 29 '17 at 17:27

jeremywoertink · Answer 1 · 2019-04-23T17:40:36.847

23

JSON is in the stdlib, so using JSON.parse is pure ruby.

require "json"
json_from_file = File.read("myfile.json")
hash = JSON.parse(json_from_file)

or just JSON.parse("{}")

If you're looking to write your own JSON parser (good luck), but just keep in mind that it's just a string when read from a file. So, start by reading it in from your file

File.open("myfile.json") do |f|
  str = f.gets
  # start parsing
end

At this point you'll need to tokenize what you read, and start picking apart each bit. Read up on the json spec.

edited Apr 23 '19 at 17:40

answered Aug 29 '17 at 17:15

jeremywoertink

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Thanks But I am newbie can you please help to write this. And +1 from side for your answer – John Ross Aug 29 '17 at 17:17
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Sorry, I actually can't. Writing a json parser shouldn't be done by a newbie because it's SUPER difficult. Just use the stdlib JSON. `require "json"` and then `JSON.parse(json_string)`. – jeremywoertink Aug 29 '17 at 17:19
I updated my example on how to parse json from a file using the standard library. Like I said, using JSON.parse is pure ruby, not an external gem. – jeremywoertink Aug 29 '17 at 17:21
He meant as in: not having to import anything. – Kevin Hernandez Feb 19 '20 at 15:39

score 2 · Answer 2 · answered Aug 29 '17 at 17:22

2

JSON is part of the core Ruby library (as of 1.9.3 I believe). You just have to require it in your ruby application/file

require 'json'

## Then you can use JSON
JSON.parse("{}")

answered Aug 29 '17 at 17:22

Richard LaFranchi

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How I can parse JSON file by pure Ruby code without gem

2 Answers2