How to sort a merged array and hash chronologically? - ruby-on-rails

Question

In a Rails 3.2 app I have a polymorphic ActivtyFeed model.
class ActivityFeed
belongs_to :user
belongs_to :feedable, polymorphic: true
end
I need to aggregate some items in the ActivityFeed index view. For example, instead of rendering separate items for each photo, I want to group photos by a date or event, and display "User uploaded x photos".
My controller looks like this:
#feed_items = #user.activity_feeds.sort_by(&:created_at)
#feed_array = []
photos = #feed_items.find_all{|f|f.feedable_type.eql?("Photo")}
#feed_items.delete_if{|f|f.feedable_type.eql?("Photo")}
#feed_array << #feed_items
grouped_photos = photos.group_by{|p| p.feedable.event_id}
#feed_array << grouped_photos
#feed_array.flatten!
Then in the views I'm using e.g.
if feed_array.class.eql?(Hash)
render grouped photo partial
elsif feed_array.feedable_type.eql?("Post")
render single post partial
etc
I'm having trouble sorting items chronologically, because the array contains a nested hash.
[#<ActivityFeed id: 7, user_id: 2, feedable_type: "Post", feedable_id: 3>, {2=>[#<ActivityFeed id 3, user_id: 4, feedable_type: "Photo", feedable_id: 6>]}]
How can I sort this array?
I've tried #feed_array.sort{|a,b| a.['created_at'] <=> b.['created_at'] } but got comparison of ActivityFeed with Hash failed
Is this the best approach, or is there a better way to go?

Answer 1

you can merge the array and the hash and then sort it
merged.sort {|a,b| a.method <=> b.method }
you only need to tell the sort how to sort the objects
one suggestion, instead of
#user.activity_feeds.sort_by(&:created_at)
do
#user.activity_feeds.order('created_at ASC')
that should be faster, since you already get the activities sorted from the database (if activity_feeds is a relation)

Answer 2

Well you need to do little bit modification to your original design.
What I would suggest is to add event to activity feed and also you need to keep the original photo to the activity feed as well.
Because, by keeping photo as a activity feed you will be able to display a single photo on your activty stream when the photo is not associated with any event. But, if every photo belongs to an event then you can remove the photo from activity feed.
Then every object will be activity feed and can be sorted easily based on created_at.
Also you don't need to extract the photos manually.
Hope this will help!