When you want to filter by date, but you've only got a datetime property, this will help you cast your datetime

arel_cast_datetime_as_as.rb

# frozen_string_literal: true
class Things < ApplicationRecord
  scope :filter_after_date, -> (date) {
    where(created_at_as_date.gteq(date))
  }
  scope :filter_before_date, -> (date) {
    where(created_at_as_date.lteq(date))
  }
  def self.created_at_as_date
    Arel::Nodes::NamedFunction.new "DATE", [ arel_table[:created_at] ]
  end
end

Explanation:

Assuming you have some Things created at 12:00 18th June 2016, and you want to query the database and retrieve only Things created on that sunny day in June. Simples, right?

SELECT "things".* FROM "things" WHERE (created_at >= '18/06/2016') AND (created_at <= '18/06/2016')

Wrong. That will result in an empty collection, however

SELECT "things".* FROM "things" WHERE (created_at::DATE >= '18/06/2016') AND (created_at::DATE <= '18/06/2016')

Will return the desired result. Here we've used postgres ::date function to cast the value to a date, thereby scraping the time and enabling the query to suck up the Things we're looking for.

This gist shows an example by using ruby's Arel library how you can cast the attribute to the date type and achieve this functionality.