A time zone database that knows the time zone of a fixed offset, such as "-05:00", and asks another database for every other zone.
Localize reads a date and time written with an offset, "10:00 GMT-5" or "2026-06-16T10:00:00-05:00", as a DateTime.t/0 whose time zone is the offset itself, "-05:00", as ECMA-262 Temporal and RFC 9557 name the zone of a fixed offset. The functions of DateTime that need only a value's own offsets work with it as it is: DateTime.to_unix/2, DateTime.to_iso8601/3, DateTime.compare/2, DateTime.diff/3 and DateTime.shift_zone/3 into another zone. The ones that look the value's own zone up in a time zone database, DateTime.add/4, DateTime.shift/3 and DateTime.from_naive/3, return an error, or raise, with a database that knows IANA's zones alone.
This database answers for the zone of a fixed offset, whose clock never changes, and passes every other zone to the database it wraps. Configure it as Elixir's database, and name the one it wraps:
config :elixir, :time_zone_database, Localize.TimeZoneDatabase
config :localize, :time_zone_database, Tz.TimeZoneDatabaseWithout :time_zone_database it wraps Tz.TimeZoneDatabase or Tzdata.TimeZoneDatabase, whichever is loaded, and else Elixir's own database of UTC alone. It may also be given to one call, as DateTime.add(datetime, 1, :hour, Localize.TimeZoneDatabase).
Summary
Functions
Returns the offset of a time zone that is a fixed offset's.
Returns the time zone of a fixed offset.
Returns the period of a time zone at a moment, given as ISO days in UTC.
Returns the period, or periods, of a time zone at a wall-clock time.
Returns the time zone database this one asks about a zone that is no fixed offset.
Functions
Returns the offset of a time zone that is a fixed offset's.
Arguments
time_zoneis a time zone, as aDateTime.t/0holds one.
Returns
{:ok, offset}, the offset from UTC in seconds, where the time zone is an offset as ISO 8601 writes one between colons, such as"+05:30","-05:00"or"-07:52:58", or:errorfor any other time zone,"Etc/UTC"and"America/New_York"among them, and for anything that is no time zone.
Examples
iex> Localize.TimeZoneDatabase.fixed_offset("+05:30")
{:ok, 19800}
iex> Localize.TimeZoneDatabase.fixed_offset("America/New_York")
:errorReturns the time zone of a fixed offset.
Arguments
offsetis an offset from UTC in seconds.
Returns
- The offset as ISO 8601 writes it between colons, with its seconds where it has them, which is the time zone of a
DateTime.t/0at that offset. No offset at all is"Etc/UTC".
Examples
iex> Localize.TimeZoneDatabase.fixed_offset_zone(-18000)
"-05:00"
iex> Localize.TimeZoneDatabase.fixed_offset_zone(0)
"Etc/UTC"Returns the period of a time zone at a moment, given as ISO days in UTC.
Arguments
iso_daysis the moment, asCalendar.iso_days/0.time_zoneis a time zone: a fixed offset's, such as"+05:30", or any the wrapped database knows.
Returns
{:ok, period}, the offset itself for a fixed offset's zone, orwhatever the wrapped database returns for any other zone.
Examples
iex> Localize.TimeZoneDatabase.time_zone_period_from_utc_iso_days({739_418, {0, 86_400}}, "+05:30")
{:ok, %{utc_offset: 19800, std_offset: 0, zone_abbr: "+05:30"}}Returns the period, or periods, of a time zone at a wall-clock time.
Arguments
naive_datetimeis the wall-clock time, aCalendar.naive_datetime/0.time_zoneis a time zone: a fixed offset's, such as"-05:00", or any the wrapped database knows.
Returns
{:ok, period}, the offset itself for a fixed offset's zone, whose clock neither skips a time nor repeats one, orwhatever the wrapped database returns for any other zone.
Examples
iex> Localize.TimeZoneDatabase.time_zone_periods_from_wall_datetime(~N[2026-06-16 10:00:00], "-05:00")
{:ok, %{utc_offset: -18000, std_offset: 0, zone_abbr: "-05:00"}}@spec wrapped() :: module()
Returns the time zone database this one asks about a zone that is no fixed offset.
Returns
The module named by
config :localize, :time_zone_database, orTz.TimeZoneDatabaseorTzdata.TimeZoneDatabase, whichever is loaded, or
Examples
iex> Localize.TimeZoneDatabase.wrapped()
Tz.TimeZoneDatabase