Forum: Ruby How do I add x months to a date

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Ben E. (Guest)
on 2007-07-03 18:14
(Received via mailing list)
I have a date

my_date = Date.new( 2007, 1, 1 )

I then have a variable holding an integer

months_to_add = 4

How do i add 'months_to_add' to my_date'?

I have spent ages googeling and looking in o'reilly ruby cookbook but no
luck;(

Any ideas?

Ben
Glen H. (Guest)
on 2007-07-03 19:04
(Received via mailing list)
You can't do it directly, date objects are immutable.

You could always get the date value from the object and then parse it,
add
the number of months you want and then create a new date object.  That
seems
like a bit of a waste though.  I would keep the date value in a string
and
manipulate it there, if and when I needed an actual date object with
that
value I would create a date object and give that out.

On 7/3/07, Ben E. <removed_email_address@domain.invalid> wrote:
>
> (email address this email is sent from may be defunct)
>
>


--
"Hey brother christian with your high and mighty errand, Your actions
speak
so loud, I can't hear a word you're saying."

-Greg Graffin (Bad Religion)
Glen H. (Guest)
on 2007-07-03 19:12
(Received via mailing list)
And when I say string you could do better and use a hash or an array.

On 7/3/07, Glen H. <removed_email_address@domain.invalid> wrote:
> On 7/3/07, Ben E. <removed_email_address@domain.invalid> wrote:
> >
> > (email address this email is sent from may be defunct)
>
--
"Hey brother christian with your high and mighty errand, Your actions
speak
so loud, I can't hear a word you're saying."

-Greg Graffin (Bad Religion)
Daniel L. (Guest)
on 2007-07-03 19:19
Ben E. wrote:
> I have a date
>
> my_date = Date.new( 2007, 1, 1 )
>
> I then have a variable holding an integer
>
> months_to_add = 4
>
> How do i add 'months_to_add' to my_date'?
>
> I have spent ages googeling and looking in o'reilly ruby cookbook but no
> luck;(
>
> Any ideas?
>
> Ben

I would do it like this, if I didn't mind loading some helpful
ActiveSupport junk:

irb> require 'active_support/core_ext/numeric'
=> true
irb> require 'active_support/core_ext/date'
=> true

irb> my_date = Date.new( 2007, 1, 1 )
=> #<Date: 4908203/2,0,2299161>

irb> my_time = my_date.to_time
=> Mon Jan 01 00:00:00 +0000 2007

irb> months_to_add = 4
=> 4

irb> new_time = my_time + months_to_add.months
=> Tue May 01 01:00:00 +0100 2007

irb> new_date = Date.new(new_time.year, new_time.month, new_time.day)
=> #<Date: 4908443/2,0,2299161>

best,
Dan
Ben E. (Guest)
on 2007-07-03 19:23
(Received via mailing list)
On 03/07/07, Glen H. <removed_email_address@domain.invalid> wrote:
> > manipulate it there, if and when I needed an actual date object with that
> > value I would create a date object and give that out.

This all seems like a lot of messing around for what should be a
standard operation.  This type of thing must exist in one of the
standard libraries.

Ben
Daniel L. (Guest)
on 2007-07-03 19:35
Ben E. wrote:
> On 03/07/07, Glen H. <removed_email_address@domain.invalid> wrote:
>> > manipulate it there, if and when I needed an actual date object with that
>> > value I would create a date object and give that out.
>
> This all seems like a lot of messing around for what should be a
> standard operation.  This type of thing must exist in one of the
> standard libraries.
>
> Ben

Actually, you are totally right. The '>>' operator does what is
required:

irb> my_date = Date.new( 2007, 1, 1 )
=> #<Date: 4908203/2,0,2299161>

irb> my_date.to_s
=> "2007-01-01"
irb> (my_date >> 4).to_s
=> "2007-05-01"

best,
Dan
Mongeta 9. (Guest)
on 2007-12-07 12:53
Daniel L. wrote:
> Ben E. wrote:
>> On 03/07/07, Glen H. <removed_email_address@domain.invalid> wrote:
>>> > manipulate it there, if and when I needed an actual date object with that
>>> > value I would create a date object and give that out.
>>
>> This all seems like a lot of messing around for what should be a
>> standard operation.  This type of thing must exist in one of the
>> standard libraries.
>>
>> Ben
>
> Actually, you are totally right. The '>>' operator does what is
> required:
>
> irb> my_date = Date.new( 2007, 1, 1 )
> => #<Date: 4908203/2,0,2299161>
>
> irb> my_date.to_s
> => "2007-01-01"
> irb> (my_date >> 4).to_s
> => "2007-05-01"
>
> best,
> Dan

I couldn't find any info about this operator >> with dates.

So, for example, if I have 2007-01-01 and I want to know the last day of
adding three months (2007-03-31) I would do:

d = Date.new(2007,1,1)
((d >> 3)-1).to_s

it works, but we can relay on this operations ?


regards,


rai
Lloyd L. (Guest)
on 2007-12-07 14:33
Ben E. wrote:
> I have a date
>
> my_date = Date.new( 2007, 1, 1 )
>
> I then have a variable holding an integer
>
> months_to_add = 4
>
> How do i add 'months_to_add' to my_date'?
>
> I have spent ages googeling and looking in o'reilly ruby cookbook but no
> luck;(
>
> Any ideas?
>
> Ben

I have not tried this but I know of something in rails that sounds
similar:
http://railshelp.com/ActiveSupport::CoreExtensions...

What if you could do something like this:

my_date = Date.new( 2007, 1, 1 )
months_to_add = 4
my_date = my_date.months_ago(months_to_add * -1)

Negative of months_ago could do it.

Shot in the dark but GL!
Mongeta 9. (Guest)
on 2007-12-07 15:57
Lloyd L. wrote:
> Ben E. wrote:
>> I have a date
>>
>> my_date = Date.new( 2007, 1, 1 )
>>
>> I then have a variable holding an integer
>>
>> months_to_add = 4
>>
>> How do i add 'months_to_add' to my_date'?
>>
>> I have spent ages googeling and looking in o'reilly ruby cookbook but no
>> luck;(
>>
>> Any ideas?
>>
>> Ben
>
> I have not tried this but I know of something in rails that sounds
> similar:
> http://railshelp.com/ActiveSupport::CoreExtensions...

I wasn't aware of this, thanks !!!

I'm using Rails so I'll try to use it.

I prefer to do in Ruby if it's possible ...


> What if you could do something like this:
>
> my_date = Date.new( 2007, 1, 1 )
> months_to_add = 4
> my_date = my_date.months_ago(months_to_add * -1)
>
> Negative of months_ago could do it.
>
> Shot in the dark but GL!

I'll try it ...

thanks,


rai
Rick D. (Guest)
on 2007-12-07 18:46
(Received via mailing list)
On 12/7/07, Raimon Fs <removed_email_address@domain.invalid> wrote:

> I couldn't find any info about this operator >> with dates.
>
> So, for example, if I have 2007-01-01 and I want to know the last day of
> adding three months (2007-03-31) I would do:
>
> d = Date.new(2007,1,1)
> ((d >> 3)-1).to_s
>
> it works, but we can relay on this operations ?

It's standard Ruby

shadowfax:~/ssanta rick$ qri "Date#<<"
---------------------------------------------------------------- Date#<<
     <<(n)
------------------------------------------------------------------------
     Return a new Date object that is n months earlier than the current
     one.

     If the day-of-the-month of the current Date is greater than the
     last day of the target month, the day-of-the-month of the returned
     Date will be the last day of the target month.

shadowfax:~/ssanta rick$ qri "Date#>>"
---------------------------------------------------------------- Date#>>
     >>(n)
------------------------------------------------------------------------
     Return a new Date object that is n months later than the current
     one.

     If the day-of-the-month of the current Date is greater than the
     last day of the target month, the day-of-the-month of the returned
     Date will be the last day of the target month.

--
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/
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