Ruby: manipulate json

on snippets, json, and ruby

I started a project, which used an existing json file full of data. Because not all data was necessary, I decided to clean it up and rename some keywords. Instead of doing that manually, I created a ruby script.

Here is an example of the input and the prefered output json:

// json we start with
[
 {
   "Country Name": "Christmas Island",
   "ISO2": "CX",
   "ISO3": "CXR",
   "Continent": "Asia",
   "Capital": "Flying Fish Cove"
 },
 {
   "Country Name": "Cocos Islands",
   "ISO2": "CC",
   "ISO3": "CCK",
   "Continent": "Asia",
   "Capital": "West Island"
 }
]
// the output we are going for
[
 {
   "name": "Christmas Island",
   "iso2": "CX",
   "continent": "Asia",
   "capital": "Flying Fish Cove"
 },
 {
   "name": "Cocos Islands",
   "iso2": "CC",
   "continent": "Asia",
   "capital": "West Island"
 }
]

This is the script used for modifying this json file:

require 'json'

file = File.read('./input.json') #1
data = JSON.parse(file) #2

output = [] #3

data.each do |child| #4
  output.push({ #5
    :name => child['Country Name'],
    :iso2 => child['ISO2'],
    :continent => child['Continent'],
    :capital => child['Capital']
  })
end

#save output to other json file
File.open('./output.json', 'w') do |f| #6
  f.write(JSON.pretty_generate(output)) #7
end

First, we read the input file (1) and parse it (2). We create an empty array that we will use for storing our new json (3). Now we loop over each existing json entry (4), create a new object, and fill that object with the information we want to keep (5). Once we have looped over all the entries, we are going to save the file as output.json. To do this, open that file as writable (6). If the file does not exist yet, it will automatically be created. For extra readability, we can pretty print the json using the pretty_generate function (7). This will ouput the file as listed above.