Jifty::DateTime(3)

NAME
Jifty::DateTime - a DateTime subclass that knows about Jifty users

SYNOPSIS
  use Jifty::DateTime;

  # Get the current date and time
  my $dt = Jifty::DateTime->now;

  # Print out the pretty date (i.e., today, tomorrow, yesterday, or 2007-09-11)
  Jifty->web->out( $dt->friendly_date );

  # Better date parsing
  my $dt_from_human = Jifty::DateTime->new_from_string("next Saturday");

DESCRIPTION
Jifty natively stores timestamps in the database in GMT. Dates are stored without timezone. This class loads and parses dates and sets them into the proper timezone.

To use this DateTime class to it's fullest ability, you'll need to add a "time_zone" method to your application's user object class. This is the class returned by "user_object" in Jifty::CurrentUser. It must return a value valid for using as an argument to DateTime's "set_time_zone()" method.

  new ARGS
See "new" in DateTime. If we get what appears to be a date, then we keep this in the floating datetime. Otherwise, set this object's timezone to the current user's time zone, if the current user's user object has a method called "time_zone".

  now ARGS
See "now" in DateTime. If a time_zone argument is passed in, then this wrapper is effectively a no-op.

OTHERWISE this will always set this object's timezone to the current user's timezone. Without this, DateTime's "now" will set the timezone to UTC always (by passing "time_zone => 'UTC'" to "Jifty::DateTime::new". We want Jifty::DateTime to always reflect the current user's timezone (unless otherwise requested, of course).

  from_epoch ARGS
See "from_epoch" in DateTime and "now" in Jifty::DateTime. This handles the common mistake of "from_epoch($epoch)" as well.

  current_user [CURRENTUSER]
When setting the current user, update the timezone appropriately.

If an "undef" current user is passed, this method will find the correct current user and set the time zone.

  current_user_has_timezone
Return timezone if the current user has one. This is determined by checking to see if the current user has a user object. If it has a user object, then it checks to see if that user object has a "time_zone" method and uses that to determine the value.

  set_current_user_timezone [DEFAULT_TZ]

  set_current_user_time_zone [DEFAULT_TZ]
Set this Jifty::DateTime's timezone to the current user's timezone. If that's not available, then use the passed in DEFAULT_TZ (or GMT if not passed in). Returns the Jifty::DateTime object itself.

If your subclass changes this method, please override "set_current_user_timezone" not "set_current_user_time_zone", since the latter is merely an alias for the former.

  new_from_string STRING[, ARGS]
Take some user defined string like "tomorrow" and turn it into a "Jifty::Datetime" object. If a "time_zone" argument is passed in, that is used for the input time zone.

If the string appears to be a _date_, the output time zone will be floating. Otherwise, the output time zone will be the current user's time zone.

As of this writing, this uses Date::Manip along with some internal hacks to alter the way Date::Manip normally interprets week day names. This may change in the future.

  friendly_date
Returns the date given by this "Jifty::DateTime" object. It will display "today" for today, "tomorrow" for tomorrow, or "yesterday" for yesterday. Any other date will be displayed in "ymd" format.

We currently shift by "24 hours" to detect yesterday and tomorrow, rather than "1 day" because of daylight saving issues. "1 day" can result in invalid local time errors.

  is_date
Returns whether or not this "Jifty::DateTime" object represents a date (without a specific time). Dates in Jifty are in the floating time zone and are set to midnight.

  get_tz_offset
Returns the offset for a time zone. If there is no current user, or the current user's time zone is unset, then UTC will be used.

The optional datetime argument lets you calculate an offset for some time other than "right now".

  jifty_serialize_format
This returns a DateTime (or string) consistent with Jifty's date format.

WHY?
There are other ways to do some of these things and some of the decisions here may seem arbitrary, particularly if you read the code. They are.

These things are valuable to applications built by Best Practical Solutions, so it's here. If you disagree with the policy or need to do it differently, then you probably need to implement something yourself using a DateTime::Format::* class or your own code.

Parts may be cleaned up and the API cleared up a bit more in the future.

SEE ALSO
DateTime, DateTime::TimeZone, Jifty::CurrentUser

LICENSE
Jifty is Copyright 2005-2010 Best Practical Solutions, LLC. Jifty is distributed under the same terms as Perl itself.