Transform DateTime into simple Date in Ruby on Rails

DateTime#to_date does exist with ActiveSupport:

$ irb
>> DateTime.new.to_date
NoMethodError: undefined method 'to_date' for #<DateTime: -1/2,0,2299161>
    from (irb):1

>> require 'active_support/core_ext'
=> true

>> DateTime.new.to_date
=> Mon, 01 Jan -4712