preserve created_at in page views from redis

fixes CNVS-5572

test-plan:
  - have page views enabled and processing through a redis queue
  - generate a new page view from a user with non-UTC time zone
  - process redis queue to persist page view
  - reload page view and check created_at; should equal the time the
    page view was created

Change-Id: I8fa4da8f81d7f18815ef9223decea433e9a71172
Reviewed-on: https://gerrit.instructure.com/20171
Reviewed-by: Brian Palmer <brianp@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>
Product-Review: Jacob Fugal <jacob@instructure.com>

app/models/page_view.rb

@@ -142,10 +142,16 @@ class PageView < ActiveRecord::Base
     raise(NotImplementedError, "find_every not implemented")
   end
 
-  def self.from_attributes(attrs)
+  def self.from_attributes(attrs, new_record=false)
     @blank_template ||= columns.inject({}) { |h,c| h[c.name] = nil; h }
     shard = cassandra? ? Shard.default : Shard.current
-    page_view = shard.activate{ instantiate(@blank_template.merge(attrs)) }
+    page_view = shard.activate do
+      if new_record
+        new{ |pv| pv.send(:attributes=, attrs, false) }
+      else
+        instantiate(@blank_template.merge(attrs))
+      end
+    end
     page_view.page_view_method = :cassandra if cassandra?
     page_view
   end
@@ -269,8 +275,7 @@ class PageView < ActiveRecord::Base
         return unless page_view
         page_view.do_update(attrs)
       else
-        page_view = self.from_attributes(attrs)
-        page_view.instance_variable_set(:'@new_record', true)
+        page_view = self.from_attributes(attrs, true)
       end
       page_view.save
     end
@@ -385,8 +390,7 @@ class PageView < ActiveRecord::Base
             false
           else
             # assumes PageView.cassandra? is true at this point
-            page_view = PageView.from_attributes(attrs)
-            page_view.instance_variable_set(:'@new_record', true)
+            page_view = PageView.from_attributes(attrs, true)
             page_view.save!
             true
           end

spec/models/page_view_spec.rb

@@ -267,6 +267,16 @@ describe PageView do
       PageView.count.should == 3
     end
 
+    it "should preserve timestamp" do
+      Time.use_zone('Alaska') do
+        pv = PageView.new{ |p| p.send(:attributes=, { :user => @user, :url => "http://test.one/", :session_id => "phony", :context => @course, :controller => 'courses', :action => 'show', :user_request => true, :render_time => 0.01, :user_agent => 'None', :account_id => Account.default.id, :request_id => "abcdef", :interaction_seconds => 5 }, false) }
+        pv.store
+        original_created_at = pv.created_at
+        PageView.process_cache_queue
+        pv.reload.created_at.to_i.should == original_created_at.to_i
+      end
+    end
+
     describe "batch transaction" do
       self.use_transactional_fixtures = false
       it "should not fail the batch if one row fails" do