app/models/import.rb in reso-0.1.1.0 vs app/models/import.rb in reso-0.1.2.0

@@ -1,25 +1,36 @@
 class Import < ActiveRecord::Base
 
-  belongs_to :import_format
+  require 'open-uri'
+  require 'open_uri_redirections'
 
+  before_save :set_import_format
+  belongs_to :import_format
   has_many :listings
   has_many :queued_listings
-  
   validates_uniqueness_of :token
 
-  before_save :set_import_format
-
-  def remove_listings_no_longer_present fresh_listing_keys
+  def remove_listings_not_present fresh_listing_keys
     existing_listing_keys = self.listings.all.pluck(:listing_key)
     stale_listing_keys = existing_listing_keys.delete_if{|key| fresh_listing_keys.include? key }
     stale_listing_keys.each do |listing_key|
       Listing.find_by(listing_key: listing_key).destroy
     end
     stale_listing_keys
   end
 
   def set_import_format
     self.import_format = ImportFormat.find_by(name: 'reso') unless self.import_format.present?
+  end
+
+  def source_url_last_modified
+    open(self.source_url, 
+      http_basic_authentication: [self.source_user, self.source_pass], 
+      allow_redirections: :all
+    ){|f| return f.last_modified }
+  end
+  
+  def new_source_data_exists?
+    self.source_data_modified.eql? self.source_url_last_modified ? false : true
   end
 
 end