extract values from json using Ruby

Question

I need to extract only the value for 'admins' from this Json using Ruby :

JSON -

 {
    "Roles":[
        {
             "admins":[
                "me"
            ],
        "role":"cleanup"
        },
    {
        "admins":[
            "tester"
        ],
        "role":"create a mess"
    },
       ]

}

RUBY -

require 'json'
file = File.read('adminlist_Feb_2017.json')
thismonthlist=JSON.parse(file)
puts thismonthlist['admins']

Output - this gives me a blank output however if i change the last line to : puts thismonthlist['Roles']

it gives me everything. I just want the list of admins.

Ursus · Accepted Answer · 2017-02-02 13:53:29Z

1

Try something like this

 thismonthlist[:Roles].flat_map { |role| role[:admins] }
 => ["me", "tester"]

answered Feb 2, 2017 at 13:53

Ursus

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Comments

guitarman · Accepted Answer · 2017-02-02 14:22:01Z

0

admins = []
File.open('adminlist_Feb_2017.json', 'r') do |file|
  json = JSON.parse(file.read)
  admins = json["Roles"].flat_map{|role| role["admins"]}.uniq
end

admins
# => ["me", "tester"]

I open the file and process it in a block to ensure it's closed at the end. In the block I read the file content and parse the json string into a hash. Then I go through the "Roles" of the hash, grab the "admins" arrays and return it as one array only with Enumerable#flat_map. After I use Enumerable#uniq to return each admin only once.

answered Feb 2, 2017 at 14:22

guitarman

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2 Comments

CodeQuay Over a year ago

Thanks,works like a charm! Just need to figure out how to remove leading spaces and general cleanup of 'admins' now. Much appreciated!

guitarman Over a year ago

I mean remove leading spaces from the admins? Try: [" me ", " tester "].map{|admin| admin.strip} # => ["me", "tester"].

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