Create a ruby hash by chaining methods.

query.rb

class Query
  def initialize
    @hash = {}
  end
 
  def method_missing(name, *args)
    value = args.length > 0 ? args.first : true
    @hash.merge!(name => value)
    self
  end
 
  def to_hash
    @hash.dup
  end
end
 
puts Query.new.female.zip("90210").city('Los Angelos').age(21).state("CA").to_hash.inspect
# => {:female=>true, :zip=>"90210", :city=>"Los Angelos", :age=>21, :state=>"CA"}

puts Query.new.for_sale.in_stock.inventory(30).current_price(3499).made_in("USA").category_code("000-001").category("product").sub_category("power cord").sub_category_code("000-009").to_hash.inspect
# => {:for_sale=>true, :in_stock=>true, :inventory=>30, :current_price=>3499, :made_in=>"USA", :category_code=>"000-001", :category=>"product", :sub_category=>"power cord", :sub_category_code=>"000-009"}