Question

I’m trying to write a Ruby program that will retrieve all the reddit usernames from a Json file. I can get it do display the list, but there is an error after the first username every time.

require 'net/http'
require 'rubygems'
require 'json'
require 'pp'

@response = Net::HTTP.get(URI.parse("http://www.reddit.com/r/AskReddit/comments/sl1nn  /could_codeine_help_me_sleep_is_it_dangerous/.json"))
result = JSON.parse(@response)

comments = result[1]['data']['children']  #this is now an array of comment hashes

(0..comments.length).each do |i|
 comment = comments[i]['data']  
 puts comment['author']
end

Although it displays the list, I also get this error:

in block in <main>': undefined method[]’ for nil:NilClass (NoMethodError)

Does anyone know I can solve this?

Answer 1

My guess is it’s the off by one error.

a = [1, 2, 3, 4, 5]
(0..a.length).map { |n| a[n] }
# => [1, 2, 3, 4, 5, nil]

This is because

(0..5).to_a
# => [0, 1, 2, 3, 4, 5]

To be non-inclusive, you should use ..., that is:

(0...comments.length).each do |i|

Better yet, since comments is an array, you can do:

comments.each do |comment|
  puts comment["data"]["author"]
end