Add intial delta work and comment on how to extend.

Author: jefferya

jupiter_output_scripts/jupiter_delta.rb

@@ -0,0 +1,36 @@
+# Delta a list of changes on Jupiter after a given date
+# base on https://github.com/ualbertalib/jupiter/pull/3626/files
+
+
+class ChangesReport
+
+  def initialize(output_directory, date)
+    @date = date 
+    @output_file = output_directory + "#{date}_changes.csv" 
+  end
+
+  def perform()
+    CSV.open(@output_file, 'wb') do |csv|
+      csv << ['type', 'id', 'changed at', 'event', 'delta']
+      PaperTrail::Version.where(created_at: @date..).find_each do |row|
+        # change delta for Item & Thesis type converting end result
+        # to DSpace/Scholaris key/value by extending the linked method
+        # test if the key exsists in the object_changes and creating a new
+        # structure in a new column listing the Scholaris key/value pairs to update
+        # https://gist.github.com/lagoan/839cf8ce997fa17b529d84776b91cdac#file-export_collections_csv-rb-L181-L196
+        csv << [row.item_type, row.item_id, row.created_at, row.event, row.object_changes]
+      end
+    end
+
+    i = Item.updated_on_or_after(@date).count
+    t = Thesis.updated_on_or_after(@date).count
+    cl = Collection.updated_on_or_after(@date).count
+    cm = Community.updated_on_or_after(@date).count
+    summary = "#{i} items, #{t} theses, #{cl} collections and #{cm} communities were created or modified."
+    puts(summary)
+
+  end
+
+end
+
+ChangesReport.new("/tmp/",Date.new(2005, 8, 8)).perform()