Just as you can use pp method to “pretty print” passed object. You can use jj to pretty print passed objects as a JSON.

The usage of it is pretty simple. All you need to pass object (or set of objects):

require 'json'

  name: "Best Lunches in Town",
  working_hours: { opens: "11:00 am", closes: "20:00 pm" },
  menu: {
    main_course: "Schnitzel with Potato",
    appetizer: "Chicken Broth",
    desser: "Pana Cota"

And the output would a well formatted JSON:

  "menu": {
    "main_course": "Schnitzel with Potato",
    "appetizer": "Chicken Broth",
    "desser": "Pana Cota"
  "working_hours": {
    "opens": "11:00 am",
    "closes": "20:00 pm"
  "name": "Best Lunches in Town"

The jj method uses JSON.pretty_generate behind the scene. It simply iterates through the passed arguments and calls pretty_generate for each of them.

That’s prretty much it.