Ruby command-line app that outputs from JSON file

The way to deal with nested if's is generally to move code into methods. Another solutions is to use an 'early return'. (if !valid b; return instead of if valid then a else b)

I would write this something like:

#!/usr/bin/ruby require 'thor' require 'json' class ListTrends < Thor VALID_API_KEY_RE = /^(?=.*[a-zA-Z])(?=.*[0-9]).{8,}$/ desc 'list_trends json', 'list out trends from JSON file' option :api_key, aliases: '--api-key', type: :string, required: true option :format, type: :string, desc: 'one line format' option :no_country_code, aliases: '--no-country-code', desc: 'remove country code', type :boolean def list_trends(keyword=nil) # Check your options before reading the file if !VALID_API_KEY_RE.match(options[:api_key]) puts "Invalid API Key, operation abort..." exit(255) end json = File.read('trends_available.json') trends_hash = JSON.parse(json) keyword = keyword.to_s.downcase trends_hash.each do |trend| process_trend(trend) end end private def process_trend(trend) return unless trend["country"].downcase.include?(keyword) if options[:format] output_formatted_trend(trend) else output_complete_trend(trend) end end def output_formatted_trend(trend) output = trend.values[0..2] output.delete_at(1) if options[:no_country_code] puts output.join(' ') end def output_complete_trend(trend) trend.each do |k, v| if v.is_a?(Hash) v.each do |i, j| puts "Trend location type #{i}: #{j}" end else puts "Trend #{k}: #{v}" end puts '' end end end ListTrends.start(ARGV) 

Another advantage being that most people can only understand a few lines of code at a time, short methods also make it easier to keep track of variable scope and giving them meaningful names makes it easier to understand code without needing comments.