Ruby: combine Date and Time objects into a DateTime

Question

Simple question, but I can\'t find a good or definitive answer. What is the best and most efficient way to combine Ruby Date and Time objects (objects, not

Answer 1

When using seconds_since_midnight, changes in daylight savings time can lead to unexpected results.

Time.zone = 'America/Chicago'
t  = Time.zone.parse('07:00').seconds_since_midnight.seconds
d1 = Time.zone.parse('2016-11-06').to_date # Fall back
d2 = Time.zone.parse('2016-11-07').to_date # Normal day
d3 = Time.zone.parse('2017-03-12').to_date # Spring forward

d1 + t
#=> Sun, 06 Nov 2016 06:00:00 CST -06:00
d2 + t
#=> Mon, 07 Nov 2016 07:00:00 CST -06:00
d3 + t
#=> Sun, 12 Mar 2017 08:00:00 CDT -05:00

Here's an alternative, similar to @selva-raj's answer above, using string interpolation, strftime, and parse. %F is equal to %Y-%m-%d and %T is equal to %H:%M:%S.

Time.zone = 'America/Chicago'
t = Time.zone.parse('07:00')
d1 = Time.zone.parse('2016-11-06').to_date # Fall back
d2 = Time.zone.parse('2016-11-07').to_date # Normal day
d3 = Time.zone.parse('2017-03-12').to_date # Spring forward

Time.zone.parse("#{d1.strftime('%F')} #{t.strftime('%T')}")
#=> Sun, 06 Nov 2016 07:00:00 CST -06:00
Time.zone.parse("#{d2.strftime('%F')} #{t.strftime('%T')}")
#=> Sun, 07 Nov 2016 07:00:00 CST -06:00
Time.zone.parse("#{d3.strftime('%F')} #{t.strftime('%T')}")
#=> Sun, 12 Mar 2017 07:00:00 CDT -05:00