Rails merge 2 query results

Question

I want to show first users with last_request >= 1.day.ago and then add the rest users

  def self.default_scope
    where("last_request >= ?", 1.day.ago) + where("last_request < ? OR last_request is null", 1.day.ago)
  end

This code raises that error:

undefined method `merge' for []:Array

How could I do that?

UPDATE

Error stack

NoMethodError - undefined method `merge' for #<Array:0xd16ba90>:
  activerecord (3.2.13) lib/active_record/relation.rb:503:in `with_default_scope'
  activerecord (3.2.13) lib/active_record/relation.rb:167:in `exec_queries'
  activerecord (3.2.13) lib/active_record/relation.rb:160:in `block in to_a'
  activerecord (3.2.13) lib/active_record/explain.rb:34:in `logging_query_plan'
  activerecord (3.2.13) lib/active_record/relation.rb:159:in `to_a'
  will_paginate (3.0.5) lib/will_paginate/active_record.rb:127:in `block in to_a'
  will_paginate (3.0.5) lib/will_paginate/collection.rb:96:in `create'
  will_paginate (3.0.5) lib/will_paginate/active_record.rb:126:in `to_a'

UPDATE2

I am using rails_admin, datetime field ordering is not working correctly

1)Order by ascending

2)Order by descending

Answer 1

In your particular case you can combine scopes to one with

   default_scope where('last_request >= :time OR (last_request < :time OR last_request IS NULL)', time: 1.day.ago).order('last_request DESC')

UPD That is not ActiveRecord or RailsAdmin issue, more info

ORDER BY ASC with Nulls at the Bottom

Rails: Order with nulls last