class QTimeZone#

QTimeZone identifies how a time representation relates to UTC. More…

Synopsis#

Methods#

def __init__()
def abbreviation()
def asBackendZone()
def comment()
def country()
def daylightTimeOffset()
def displayName()
def fixedSecondsAheadOfUtc()
def hasDaylightTime()
def hasTransitions()
def id()
def isDaylightTime()
def isUtcOrFixedOffset()
def isValid()
def nextTransition()
def offsetData()
def offsetFromUtc()
def __ne__()
def __eq__()
def previousTransition()
def standardTimeOffset()
def swap()
def territory()
def timeSpec()
def transitions()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description#

When dates and times are combined, the meaning of the result depends on how time is being represented. There are various international standards for representing time; one of these, UTC, corresponds to the traditional standard of solar mean time at Greenwich (a.k.a. GMT). All other time systems supported by Qt are ultimately specified in relation to UTC. An instance of this class provides a stateless calculator for conversions between UTC and other time representations.

Some time representations are simply defined at a fixed offset to UTC. Others are defined by governments for use within their jurisdictions. The latter are properly known as time zones, but QTimeZone (since Qt 6.5) is unifies their representation with that of general time systems. One time zone generally supported on most operating systems is designated local time; this is presumed to correspond to the time zone within which the user is living.

For time zones other than local time, UTC and those at fixed offsets from UTC, Qt can only provide support when the operating system provides some way to access that information. When Qt is built, the timezone feature controls whether such information is available. When it is not, some constructors and methods of QTimeZone are excluded from its API; these are documented as depending on feature timezone. Note that, even when Qt is built with this feature enabled, it may be unavailable to users whose systems are misconfigured, or where some standard packages (for example, the tzdata package on Linux) are not installed. This feature is enabled by default when time zone information is available.

This class is primarily designed for use in QDateTime ; most applications will not need to access this class directly and should instead use an instance of it when constructing a QDateTime .

Note

For consistency with QDateTime , QTimeZone does not account for leap seconds.

Remarks#

QTimeZone , like QDateTime , measures offsets from UTC in seconds. This contrasts with their measurement of time generally, which they do in milliseconds. Real-world time zones generally have UTC offsets that are whole-number multiples of five minutes (300 seconds), at least since well before 1970. A positive offset from UTC gives a time representation puts noon on any given day before UTC noon on that day; a negative offset puts noon after UTC noon on the same day.

Lightweight Time Representations#

QTimeZone can represent UTC, local time and fixed offsets from UTC even when feature timezone is disabled. The form in which it does so is also available when the feature is enabled; it is a more lightweight form and processing using it will typically be more efficient, unless methods only available when feature timezone is enabled are being exercised. See Initialization and fromSecondsAheadOfUtc(int) for how to construct these representations.

This documentation distinguishes between “time zone”, used to describe a time representation described by system-supplied or standard information, and time representations more generally, which include these lightweight forms. The methods available only when feature timezone is enabled are apt to be cheaper for time zones than for lightweight time representations, for which these methods may construct a suitable transient time zone object to which to forward the query.

IANA Time Zone IDs#

QTimeZone uses the IANA time zone IDs as defined in the IANA Time Zone Database (http://www.iana.org/time-zones). This is to ensure a standard ID across all supported platforms. Most platforms support the IANA IDs and the IANA Database natively, but for Windows a mapping is required to the native IDs. See below for more details.

The IANA IDs can and do change on a regular basis, and can vary depending on how recently the host system data was updated. As such you cannot rely on any given ID existing on any host system. You must use availableTimeZoneIds() to determine what IANA IDs are available.

The IANA IDs and database are also know as the Olson IDs and database, named after the original compiler of the database.

UTC Offset Time Zones#

A default UTC time zone backend is provided which is always available when feature timezone is enabled. This provides a set of generic Offset From UTC time zones in the range UTC-16:00 to UTC+16:00. These time zones can be created using either the standard ISO format names, such as “UTC+00:00”, as listed by availableTimeZoneIds() , or using a name of similar form in combination with the number of offset seconds.

Windows Time Zones#

Windows native time zone support is severely limited compared to the standard IANA TZ Database. Windows time zones cover larger geographic areas and are thus less accurate in their conversions. They also do not support as much historical data and so may only be accurate for the current year. In particular, when MS’s zone data claims that DST was observed prior to 1900 (this is historically known to be untrue), the claim is ignored and the standard time (allegedly) in force in 1900 is taken to have always been in effect.

QTimeZone uses a conversion table derived from the Unicode CLDR data to map between IANA IDs and Windows IDs. Depending on your version of Windows and Qt, this table may not be able to provide a valid conversion, in which “UTC” will be returned.

QTimeZone provides a public API to use this conversion table. The Windows ID used is the Windows Registry Key for the time zone which is also the MS Exchange EWS ID as well, but is different to the Time Zone Name (TZID) and COD code used by MS Exchange in versions before 2007.

Note

When Qt is built with the ICU library, it is used in preference to the Windows system APIs, bypassing all problems with those APIs using different names.

System Time Zone#

The method systemTimeZoneId() returns the current system IANA time zone ID which on Unix-like systems will always be correct. On Windows this ID is translated from the Windows system ID using an internal translation table and the user’s selected country. As a consequence there is a small chance any Windows install may have IDs not known by Qt, in which case “UTC” will be returned.

Creating a new QTimeZone instance using the system time zone ID will only produce a fixed named copy of the time zone, it will not change if the system time zone changes. systemTimeZone() will return an instance representing the zone named by this system ID. Note that constructing a QDateTime using this system zone may behave differently than constructing a QDateTime that uses LocalTime as its TimeSpec , as the latter directly uses system APIs for accessing local time information, which may behave differently (and, in particular, might adapt if the user adjusts the system zone setting).

Time Zone Offsets#

The difference between UTC and the local time in a time zone is expressed as an offset in seconds from UTC, i.e. the number of seconds to add to UTC to obtain the local time. The total offset is comprised of two component parts, the standard time offset and the daylight-saving time offset. The standard time offset is the number of seconds to add to UTC to obtain standard time in the time zone. The daylight-saving time offset is the number of seconds to add to the standard time offset to obtain daylight-saving time (abbreviated DST and sometimes called “daylight time” or “summer time”) in the time zone. The usual case for DST (using standard time in winter, DST in summer) has a positive daylight-saving time offset. However, some zones have negative DST offsets, used in winter, with summer using standard time.

Note that the standard and DST offsets for a time zone may change over time as countries have changed DST laws or even their standard time offset.

License#

This class includes data obtained from the CLDR data files under the terms of the Unicode Data Files and Software License. See Unicode Common Locale Data Repository (CLDR) for details.

See also

QDateTime QCalendar

class Initialization#

The type of the simplest lightweight time representations.

This enumeration identifies a type of lightweight time representation to pass to a QTimeZone constructor, where no further data are required. They correspond to the like-named members of TimeSpec .

Constant

Description

QTimeZone.LocalTime

This time representation corresponds to the one implicitly used by system functions using time_t and struct tm value to map between local time and UTC time.

QTimeZone.UTC

This time representation, Coordinated Universal Time, is the base representation to which civil time is referred in all supported time representations. It is defined by the International Telecommunication Union.

Constant	Description
QTimeZone.LocalTime	This time representation corresponds to the one implicitly used by system functions using `time_t` and `struct tm` value to map between local time and UTC time.
QTimeZone.UTC	This time representation, Coordinated Universal Time, is the base representation to which civil time is referred in all supported time representations. It is defined by the International Telecommunication Union.

New in version 6.5.

class TimeType#

The type of time zone time, for example when requesting the name. In time zones that do not apply DST, all three values may return the same result.

Constant

Description

QTimeZone.StandardTime

The standard time in a time zone, i.e. when Daylight-Saving is not in effect. For example when formatting a display name this will show something like “Pacific Standard Time”.

QTimeZone.DaylightTime

A time when Daylight-Saving is in effect. For example when formatting a display name this will show something like “Pacific daylight-saving time”.

QTimeZone.GenericTime

A time which is not specifically Standard or Daylight-Saving time, either an unknown time or a neutral form. For example when formatting a display name this will show something like “Pacific Time”.

Constant	Description
QTimeZone.StandardTime	The standard time in a time zone, i.e. when Daylight-Saving is not in effect. For example when formatting a display name this will show something like “Pacific Standard Time”.
QTimeZone.DaylightTime	A time when Daylight-Saving is in effect. For example when formatting a display name this will show something like “Pacific daylight-saving time”.
QTimeZone.GenericTime	A time which is not specifically Standard or Daylight-Saving time, either an unknown time or a neutral form. For example when formatting a display name this will show something like “Pacific Time”.

This type is only available when feature timezone is enabled.

class NameType#

The type of time zone name.

Constant

Description

QTimeZone.DefaultName

The default form of the time zone name, e.g. LongName, ShortName or OffsetName

QTimeZone.LongName

The long form of the time zone name, e.g. “Central European Time”

QTimeZone.ShortName

The short form of the time zone name, usually an abbreviation, e.g. “CET”

QTimeZone.OffsetName

The standard ISO offset form of the time zone name, e.g. “UTC+01:00”

Constant	Description
QTimeZone.DefaultName	The default form of the time zone name, e.g. LongName, ShortName or OffsetName
QTimeZone.LongName	The long form of the time zone name, e.g. “Central European Time”
QTimeZone.ShortName	The short form of the time zone name, usually an abbreviation, e.g. “CET”
QTimeZone.OffsetName	The standard ISO offset form of the time zone name, e.g. “UTC+01:00”

This type is only available when feature timezone is enabled.

PySide6.QtCore.QTimeZone.MinUtcOffsetSecs#

PySide6.QtCore.QTimeZone.MaxUtcOffsetSecs#

__init__(spec)#

Parameters:: spec – Initialization

Creates a lightweight instance describing UTC or local time.

See also

fromSecondsAheadOfUtc() asBackendZone() utc() systemTimeZone()

__init__()

Create a null/invalid time zone instance.

__init__(offsetSeconds)

Parameters:: offsetSeconds – int

Creates a time zone instance with the given offset, offsetSeconds, from UTC.

The offsetSeconds from UTC must be in the range -16 hours to +16 hours otherwise an invalid time zone will be returned.

This constructor is only available when feature timezone is enabled. The returned instance is equivalent to the lightweight time representation QTimeZone::fromSecondsAfterUtc(offsetSeconds), albeit implemented as a time zone.

See also

MinUtcOffsetSecs MaxUtcOffsetSecs id()

__init__(other)

Parameters:: other – QTimeZone

Copy constructor: copy other to this.

__init__(ianaId)

Parameters:: ianaId – QByteArray

Creates a time zone instance with the requested IANA ID ianaId.

The ID must be one of the available system IDs or a valid UTC-with-offset ID, otherwise an invalid time zone will be returned. For UTC-with-offset IDs, when they are not in fact IANA IDs, the id() of the resulting instance may differ from the ID passed to the constructor.

This constructor is only available when feature timezone is enabled.

See also

availableTimeZoneIds() id()

__init__(zoneId, offsetSeconds, name, abbreviation[, territory=QLocale.AnyTerritory[, comment=""]])

Parameters:

zoneId – QByteArray
offsetSeconds – int
name – str
abbreviation – str
territory – Country
comment – str

Creates a custom time zone instance at fixed offset from UTC.

The returned time zone has an ID of zoneId and an offset from UTC of offsetSeconds. The name will be the name used by displayName() for the LongName , the abbreviation will be used by displayName() for the ShortName and by abbreviation() , and the optional territory will be used by territory() . The comment is an optional note that may be displayed in a GUI to assist users in selecting a time zone.

The zoneId must not be one of the available system IDs returned by availableTimeZoneIds() . The offsetSeconds from UTC must be in the range -16 hours to +16 hours.

If the custom time zone does not have a specific territory then set it to the default value of AnyTerritory .

This constructor is only available when feature timezone is enabled.

See also

id() offsetFromUtc() displayName() abbreviation() territory() comment() MinUtcOffsetSecs MaxUtcOffsetSecs

abbreviation(atDateTime)#

Parameters:: atDateTime – QDateTime
Return type:: str

Returns the time zone abbreviation at the given atDateTime. The abbreviation may change depending on DST or even historical events.

Note that the abbreviation is not guaranteed to be unique to this time zone and should not be used in place of the ID or display name.

This method is only available when feature timezone is enabled.

See also

displayName()

asBackendZone()#

Return type:: QTimeZone

Converts this QTimeZone to one whose timeSpec() is TimeZone .

In all cases, the result’s timeSpec() is TimeZone . When this QTimeZone ‘s timeSpec() is TimeZone , this QTimeZone itself is returned. If timeSpec() is LocalTime then systemTimeZone() is returned.

If timeSpec() is UTC , utc() is returned. If it is OffsetFromUTC then QTimeZone (int) is passed its offset and the result is returned.

When using a lightweight time representation - local time, UTC time or time at a fixed offset from UTC - using methods only supported when feature timezone is enabled may be more expensive than using a corresponding time zone. This method maps a lightweight time representation to a corresponding time zone - that is, an instance based on system-supplied or standard data.

This method is only available when feature timezone is enabled.

See also

Initialization) fromSecondsAheadOfUtc()

static availableTimeZoneIds()#

Return type:: .list of QByteArray

Returns a list of all available IANA time zone IDs on this system.

This method is only available when feature timezone is enabled.

Note

the QTimeZone constructor will also accept some UTC-offset IDs that are not in the list returned - it would be impractical to list all possible UTC-offset IDs.