How can I add minutes,seconds and hours to a DateTime object?

Ruby
1

require ‘date’
require ‘time’

text_t = “1:40 PM ET”
dt = DateTime.parse(text_t) # => #<DateTime: 2013-07-02T13:40:00+00:00
((2456476j,49200s,0n),+0s,2299161j)>
dt.send(:minute) # => 40
dt.minute # => 40

Any way to add say 2 hours,5 minutes and 2 seconds to the dt object.

2

On 07/02/2013 11:23 AM, Love U Ruby wrote:

No, you cannot modify Date/DateTime objects. You must create a new one
with the values you want:

-Justin

3

Justin C. wrote in post #1114234:

On 07/02/2013 11:23 AM, Love U Ruby wrote:

No, you cannot modify Date/DateTime objects. You must create a new one
with the values you want:
Class: Date (Ruby 2.0.0)

I reached till this point:

require ‘date’

text_t = ‘2:12:03 PM ET’
dt = DateTime.parse(text_t, ‘%I:%M %p %Z’)

=> #<DateTime: 2013-07-03T14:12:03+00:00

((2456477j,51123s,0n),+0s,2299161j)>
dt.to_s

=> “2013-07-03T14:12:03+00:00”

Date._strptime(dt.to_s,‘%Y-%m-%dT%H:%M:%S%z’)

=> {:year=>2013,

:mon=>7,

:mday=>3,

:hour=>14,

:min=>12,

:sec=>3,

:zone=>“+00:00”,

:offset=>0}

Any way to convert this Hash object back to Date object? If that can be
done,I think problem will be solved.

4

finally I came up with as below :

require ‘date’

text_t = ‘2:12:03 PM ET’
dt = DateTime.parse(text_t, ‘%I:%M %p %Z’)

=> #<DateTime: 2013-07-03T14:12:03+00:00

((2456477j,51123s,0n),+0s,2299161j)>
dt.to_s

=> “2013-07-03T14:12:03+00:00” # !> invalid offset is ignored

dh = Date._strptime(dt.to_s,’%Y-%m-%dT%H:%M:%S%z’)

=> {:year=>2013,

:mon=>7,

:mday=>3,

:hour=>14,

:min=>12,

:sec=>3,

:zone=>"+00:00",

:offset=>0}

dh[:hour] += 30 # => 44
dh

=> {:year=>2013,

:mon=>7,

:mday=>3,

:hour=>44,

:min=>12,

:sec=>3,

:zone=>"+00:00",

:offset=>0}

dh.values[0…-2].join(" ")

=> “2013 7 3 44 12 3 +00:00”

DateTime.ordinal(*dh.values[0…-3])

=> #<DateTime: 2013-01-07T03:44:12+00:00

((2456300j,13452s,0n),+0s,2299161j)>

Please suggest me if any wrong calculation has been made by me? Please

Thanks

5

On 2013-07-02, at 3:41 PM, Love U Ruby [email protected] wrote:

dh = Date._strptime(dt.to_s,‘%Y-%m-%dT%H:%M:%S%z’)
dh

=> “2013 7 3 44 12 3 +00:00”

DateTime.ordinal(*dh.values[0…-3])

=> #<DateTime: 2013-01-07T03:44:12+00:00

((2456300j,13452s,0n),+0s,2299161j)>

Please suggest me if any wrong calculation has been made by me? Please

Thanks

–
Posted via http://www.ruby-forum.com/.

It does seem odd that 30 hours after 2013-07-03T14:12:03+00:00 is
2013-01-07T03:44:12+00:00, and you do seem to be doing a lot of work to
add 30 hours - looking a the code there is a lot of “noise”.

If I look at the documentation for DateTime then I see I can use + to
add a fractional number of days,

, so:

ratdog:tmp mike$ pry
[1] pry(main)> require ‘date’
=> false
[2] pry(main)> dt = DateTime.parse(‘2:12:03 PM ET’, ‘%I:%M %p %Z’)
=> #<DateTime: 2013-07-02T14:12:03+00:00
((2456476j,51123s,0n),+0s,2299161j)>
[3] pry(main)> dt + (30.0 / 24) # days
=> #<DateTime: 2013-07-03T20:12:03+00:00
((2456477j,72723s,0n),+0s,2299161j)>

Hope this helps,

Mike

–

Mike S. [email protected]
http://www.stok.ca/~mike/

The “`Stok’ disclaimers” apply.

6

On 7/2/2013 4:33 PM, Mike S. wrote:

dt.to_s

=> #<DateTime: 2013-07-02T14:12:03+00:00 ((2456476j,51123s,0n),+0s,2299161j)>
[3] pry(main)> dt + (30.0 / 24) # days
=> #<DateTime: 2013-07-03T20:12:03+00:00 ((2456477j,72723s,0n),+0s,2299161j)>

Both approaches make me nervous. The first because your parsing a date
where the time is 44:00 (clearly an invalid date), which at best I
believe is undocumented behavior, and more likely is exploiting a bug
that may be fixed at a later date.

The is Mike’s is probably fine, but makes me worry about rounding errors
for some values. Instead I’d do the math using Time, which uses seconds
instead of fractions of days:

irb(main):006:0> now = DateTime.now.to_time
=> 2013-07-02 22:09:19 -0600
irb(main):007:0> hours = 2
=> 2
irb(main):008:0> minutes = 5
=> 5
irb(main):010:0> now + (hours * 60 * 60) + minutes * 60
=> 2013-07-03 00:14:19 -0600

Ideally the Stdlib would have a TimeSpan class which could be added and
subtracted from DateTime, or be the result of subtracting 2 DateTimes.
Would be a good idea for a gem.