Rails - Nov 2009 - getting the timezone name from an abbreviation

HI,

I am creating n onlinecalendar sort of functionality for which the
user input for events is taken. To make it user friendly, its left to
the user to write the time down rather than selecting it from a
datetime field in a form
.
The user can also specify a timezone. And while doing so its obvious
that most inputs will be an abbreviation.

My question is - is there a way to convert "PST" into the required
timezone name or at least get the UTC offset for it?

Thanks in advance

dewdrops wrote:
> My question is - is there a way to convert "PST" into the
required
> timezone name or at least get the UTC offset for it?
Well, actually there is no "safe" way to do that. Some time zones
share
the same abbreviation. For example CST has at least three matching time 
zones:

- Central Standard Time - USA
- Central Standard Time - Australia
- Central Summer Time - Australia

Yes, you read that correctly Australia, apparently, uses CST for both 
"Standard" UTC+9.30 and "Summer" UTC+10.30.

Besides that. Do you want to accept their word for it if it''s daylight 
savings time or not? They might enter EST or EDT for example? You would 
have to take responsibility for that in your application anyway.
-- 
Posted via http://www.ruby-forum.com/.

On Nov 10, 8:31 pm, Robert Walker
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> dewdrops wrote:
> > My question is - is there a way to convert "PST" into the
required
> > timezone name or at least get the UTC offset for it?
>
> Well, actually there is no "safe" way to do that. Some time zones
share
> the same abbreviation. For example CST has at least three matching time
> zones:
>
Also, how many ordinary know their time zone abbreviations ?

Fred
> - Central Standard Time - USA
> - Central Standard Time - Australia
> - Central Summer Time - Australia
>
> Yes, you read that correctly Australia, apparently, uses CST for both
> "Standard" UTC+9.30 and "Summer" UTC+10.30.
>
> Besides that. Do you want to accept their word for it if it''s
daylight
> savings time or not? They might enter EST or EDT for example? You would
> have to take responsibility for that in your application anyway.
> --
> Posted viahttp://www.ruby-forum.com/.

Frederick Cheung wrote:
[...]
> Also, how many ordinary know their time zone abbreviations ?
And how many time zones even have standard abbreviations?  Just give the 
user a menu.
> 
> Fred
Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org
-- 
Posted via http://www.ruby-forum.com/.

hmmm .. true  but what if you are accepting an email from the user to
set the task in your calendar app??

The only othe option is somehow get the ''email
sender''s'' IP to place
him in some timezone or
Try to get the time from the email but all i got was the datetime of
the email server they sent the email from (eg gmail etc).

Any suggestions on this issue??

On Nov 11, 2:24 am, Marnen Laibow-Koser <rails-mailing-l...@andreas-
s.net> wrote:
> Frederick Cheung wrote:
>
> [...]
>
> > Also, how many ordinary know their time zone abbreviations ?
>
> And how many time zones even have standard abbreviations?  Just give the
> user a menu.
>
>
>
> > Fred
>
> Best,
> --
> Marnen Laibow-Koserhttp://www.marnen.org
> mar...-sbuyVjPbboAdnm+yROfE0A@public.gmane.org
> --
> Posted viahttp://www.ruby-forum.com/.

dewdrops wrote:
> hmmm .. true  but what if you are accepting an email from the user to
> set the task in your calendar app??
> 
> The only othe option is somehow get the ''email
sender''s'' IP to place
> him in some timezone or
> Try to get the time from the email but all i got was the datetime of
> the email server they sent the email from (eg gmail etc).
> 
> Any suggestions on this issue??
> 
> On Nov 11, 2:24�am, Marnen Laibow-Koser <rails-mailing-l...@andreas-
A possible solution is to ask your users what their local time zone is 
using the time zone select helper. Then store that value in their user 
record. Then assume all times are in the time zone that you store for 
them.

Dealing with time zones is not a trivial issue and you won''t be able to
rely on time zone names or abbreviations. As mentioned earlier, users 
will probably not even know what to enter anyway.
-- 
Posted via http://www.ruby-forum.com/.

On Tue, Nov 10, 2009 at 3:31 PM, Robert Walker
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
>
> Well, actually there is no "safe" way to do that. Some time zones
share
> the same abbreviation. For example CST has at least three matching time
> zones:
>
> - Central Standard Time - USA
> - Central Standard Time - Australia
> - Central Summer Time - Australia
>
> Yes, you read that correctly Australia, apparently, uses CST for both
> "Standard" UTC+9.30 and "Summer" UTC+10.30.
Interesting, although I find it hard to believe that any self
respecting Aussie  would use Central Summer Time, since the normal
name is Central Daylight Time, and I''d suspect that "Summer
Time"
would be considered a Pommie afectation.

Most countries which use Summer instead of Daylight in TZ period
abreviations seem to not use the lack of a letter, or an entirely
different abbreviation for the winter time

GMT, and BST, or IST

CET, and CEST

etc.

but it''s quite true that time zone period abbreviations can''t
in
general be used to identify a particular time zone, even at a given
period of time. Another complication being that such things tend to
change with new governents, laws, and whims.

A good list of abbreviations can be found at:

http://www.timeanddate.com/library/abbreviations/timezones/

-- 
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale
WWR: http://www.workingwithrails.com/person/9021-rick-denatale
LinkedIn: http://www.linkedin.com/in/rickdenatale