ML query

query.rb

# Get the count of notifications for this user 
# and this post that need to be sent or have *not* 
# been sent in the past 24 hours

User.
  where({ _id: user._id, "notifs.post_id" => post_id }).
  any_of(
    { "notifs.needs_send" => true }, 
    { "notifs.last_send" => { '$exists' => false }},
    { "notifs.last_send" => { "$lt" => 1.days.ago.utc }}
  ).count