Set time part of DateTime in ruby

Within a Rails environment:

Thanks to ActiveSupport you can use:

DateTime.now.midnight
DateTime.now.beginning_of_day

OR

DateTime.now.change({ hour: 0, min: 0, sec: 0 })

# More concisely
DateTime.now.change({ hour: 0 })                

Within a purely Ruby environment:

now = DateTime.now
DateTime.new(now.year, now.month, now.day, 0, 0, 0, now.zone)

OR

now = DateTime.now
DateTime.parse(now.strftime("%Y-%m-%dT00:00:00%z"))