Observe issue, merge request, note creation - create event

app/models/activity_observer.rb

@@ -0,0 +1,12 @@
+class ActivityObserver < ActiveRecord::Observer
+  observe :issue, :merge_request, :note
+
+  def after_create(record)
+    Event.create(
+      :project => record.project,
+      :target_id => record.id,
+      :target_type => record.class.name,
+      :action => Event.determine_action(record)
+    )
+  end
+end