Stripping and pushing strings into an array

Question

I am running my program locally through my bin folder; this is just a small CLI project. I am trying to strip and push strings into an array.

Here is my code:

require 'nokogiri'
require 'open-uri'

module BestPlaces
  class Places
    attr_accessor :name, :population, :places

      def initialize
        @places = []
      end

      def self.scrape_places
        doc = Nokogiri::HTML(open("https://nomadlist.com/best-cities-to-live"))
        places = doc.search("div.text h2.itemName")
        ranks = doc.search("div.rank")
        places.each{|e| @places << e.text.strip}

          @places.each do |place|
            i = @places.index(place)
          puts "#{ranks[i].text}. #{place}"
        end
      end
    end

     class CLI
       def list_places
         puts "Welcome to the best places on Earth!"
         BestPlaces::Places.scrape_places
       end

       def call
         list_places
         menu
         goodbye
       end
     end
  end

When I run my program, I get an error:

block in scrape_places': undefined method `<<' for nil:NilClass (NoMethodError)

Any suggestions are much appreciated.

Fangxing · Accepted Answer · 2017-05-30T01:55:38.750

In short: you got undefined method '<<' for nil:NilClass, because you are try manipulate an class instance variable @places and it's value is nil.

The first one @places in method initialize is an object instance variable, you set its value to [], but the second one @places in class method self.scrape_places is a class instance variable, you did't give any value to it, so it's nil by default. Notice the two variable are not the same. Since you supposed they are the same, so you may want change def self.scrape_places to def scrape_places, then they will be the same object instance variable.

Stripping and pushing strings into an array

1 Answers1