ruby json.pretty_generate output

Question

SO i have this code that reads a file and check for certain value, if it finds these words the key-word will be written to a json file. except the problem is that it writes an unnecessary value.

require 'json'

lines = IO.readlines('dhcpd.conf')
host = nil
eth = nil
address = nil

hosts = {}

lines.each do |line|
  if line =~ /^host\s+(.+)\s+{$/
   host = $1
   eth = nil
   address = nil

  elsif line =~ /^\s*hardware ethernet (.*);$/
   eth = $1
  elsif line =~ /^\s*fixed-address (.*);$/
   address = $1
  elsif line =~ /^}$/
   hosts[host] = {name: host, mac: eth, ip: address}
 end
end

file = File.new("new_computers.json", "w")
file.puts "["
file.puts JSON.pretty_generate(hosts)
file.puts "]"

This is the output I get:

[
 {
   "Mike": {
    "name": "Mike",
    "mac": "a1:b2:c3:d4:e5:f6",
    "ip": "192.168.1.1"
 },
   "Mike2": {
    "name": "Mike2",
    "mac": "aa:bb:cc:dd:ee:ff",
    "ip": "192.168.1.2"
 },
 ...
 ...
 ...
]

But want the output to be:

[
 {
   "name" : "Mike"
   "mac" : "a1:b2:c3:d4:e5:f6"
   "ip" : "192.168.1.1"
 },
...
...
...
]

I have tried all kinds of things, but i can't get the right.

Since you are building the hosts hash yourself, why not just create it in the format you need? Or do you need the format you are creating right now at some other part of the code? — Michael Kohl
– Michael Kohl, Commented May 8, 2015 at 9:26

Pramod Shinde · Accepted Answer · 2015-05-08 10:06:32Z

1

First change hosts to array, if you are not using hosts as Hash in other places.

hosts = []

Then while adding to the hosts do this, if you are interested in only :name, :mac, :ip and not :host as key in file

hosts << {name: host, mac: eth, ip: address}

Change writing logic to

file = File.new("new_computers.json", "w")
file.puts JSON.pretty_generate(hosts)

Should see the expected data

answered May 8, 2015 at 10:06

Pramod Shinde

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5qFf3dmhkQ Over a year ago

You sir, you're my saviour!

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