Example of literally defined aggregate methods for use in blog post.

literally_defined_methods.rb

def self.count_vhs_by_rentals
  Rental.all.each_with_object({}) do |rental, vhs_hash| 
    vhs_hash[rental.vhs].nil? ? vhs_hash[rental.vhs] = 1 : vhs_hash[rental.vhs] += 1 
  end
end 
#=> {<Vhs:0x00007f8d5e2bf0f0 id: 17, serial_number: "MAX-luqovgdk8e7tl", movie_id: 9 => 1,
 #<Vhs:0x00007f8d4f81a4a0 id: 29, serial_number: "BABA-t6k24krzqclts", movie_id: 13 =>2,
 #<Vhs:0x00007f8d4f854538 id: 11, serial_number: "BABA-begvxe7ai0rc6", movie_id: 13 =>3}

def self.count_vhs_by_client
  Rental.all.each_with_object({}) do |rental, vhs_hash| 
    vhs_hash[rental.client].nil? ? vhs_hash[rental.client] = 1 : vhs_hash[rental.client] += 1 
  end
end

#=> {#<Client:0x00007f872c1bb4c0 id: 4, name: "Hank Jennings" =>1,
     #<Client:0x00007f872c1c8fd0 id: 7, name: "Lisa Wilkes" =>2