Added support for time zones. Thanks Luke Plant for the review. Fixed #2626.

For more information on this project, see this thread:
http://groups.google.com/group/django-developers/browse_thread/thread/cf0423bbb85b1bbf



git-svn-id: http://code.djangoproject.com/svn/django/trunk@17106 bcc190cf-cafb-0310-a4f2-bffc1f526a37

4 files changed, 219 insertions, 36 deletions

diff --git a/docs/ref/models/querysets.txt b/docs/ref/models/querysets.txt
index 68da9c7343..9736d94838 100644
--- a/docs/ref/models/querysets.txt
+++ b/docs/ref/models/querysets.txt
@@ -546,6 +546,12 @@ Examples::
     >>> Entry.objects.filter(headline__contains='Lennon').dates('pub_date', 'day')
     [datetime.datetime(2005, 3, 20)]
 
+.. warning::
+
+    When :doc:`time zone support </topics/i18n/timezones>` is enabled, Django
+    uses UTC in the database connection, which means the aggregation is
+    performed in UTC. This is a known limitation of the current implementation.
+
 none
 ~~~~
 
@@ -1953,6 +1959,13 @@ Note this will match any record with a ``pub_date`` that falls on a Monday (day
 2 of the week), regardless of the month or year in which it occurs. Week days
 are indexed with day 1 being Sunday and day 7 being Saturday.
 
+.. warning::
+
+    When :doc:`time zone support </topics/i18n/timezones>` is enabled, Django
+    uses UTC in the database connection, which means the ``year``, ``month``,
+    ``day`` and ``week_day`` lookups are performed in UTC. This is a known
+    limitation of the current implementation.
+
 .. fieldlookup:: isnull
 
 isnull
diff --git a/docs/ref/settings.txt b/docs/ref/settings.txt
index 20366e353d..0d91f16821 100644
--- a/docs/ref/settings.txt
+++ b/docs/ref/settings.txt
@@ -1810,6 +1810,7 @@ Default::
     "django.core.context_processors.i18n",
     "django.core.context_processors.media",
     "django.core.context_processors.static",
+    "django.core.context_processors.tz",
     "django.contrib.messages.context_processors.messages")
 
 A tuple of callables that are used to populate the context in ``RequestContext``.
@@ -1830,6 +1831,10 @@ of items to be merged into the context.
     The ``django.core.context_processors.static`` context processor
     was added in this release.
 
+.. versionadded:: 1.4
+    The ``django.core.context_processors.tz`` context processor
+    was added in this release.
+
 .. setting:: TEMPLATE_DEBUG
 
 TEMPLATE_DEBUG
@@ -1971,6 +1976,9 @@ Default: ``'America/Chicago'``
 .. versionchanged:: 1.2
    ``None`` was added as an allowed value.
 
+.. versionchanged:: 1.4
+   The meaning of this setting now depends on the value of :setting:`USE_TZ`.
+
 A string representing the time zone for this installation, or
 ``None``. `See available choices`_. (Note that list of available
 choices lists more than one on the same line; you'll want to use just
@@ -1978,16 +1986,19 @@ one of the choices for a given time zone. For instance, one line says
 ``'Europe/London GB GB-Eire'``, but you should use the first bit of
 that -- ``'Europe/London'`` -- as your :setting:`TIME_ZONE` setting.)
 
-Note that this is the time zone to which Django will convert all
-dates/times -- not necessarily the timezone of the server. For
-example, one server may serve multiple Django-powered sites, each with
-a separate time-zone setting.
+Note that this isn't necessarily the timezone of the server. For example, one
+server may serve multiple Django-powered sites, each with a separate time zone
+setting.
+
+When :setting:`USE_TZ` is ``False``, this is the time zone in which Django will
+store all datetimes. When :setting:`USE_TZ` is ``True``, this is the default
+time zone that Django will use to display datetimes in templates and to
+interpret datetimes entered in forms.
 
-Normally, Django sets the ``os.environ['TZ']`` variable to the time
-zone you specify in the :setting:`TIME_ZONE` setting. Thus, all your views
-and models will automatically operate in the correct time zone.
-However, Django won't set the ``TZ`` environment variable under the
-following conditions:
+Django sets the ``os.environ['TZ']`` variable to the time zone you specify in
+the :setting:`TIME_ZONE` setting. Thus, all your views and models will
+automatically operate in this time zone. However, Django won't set the ``TZ``
+environment variable under the following conditions:
 
 * If you're using the manual configuration option as described in
   :ref:`manually configuring settings
@@ -2004,7 +2015,6 @@ to ensure your processes are running in the correct environment.
     environment. If you're running Django on Windows, this variable
     must be set to match the system timezone.
 
-
 .. _See available choices: http://www.postgresql.org/docs/8.1/static/datetime-keywords.html#DATETIME-TIMEZONE-SET-TABLE
 
 .. setting:: URL_VALIDATOR_USER_AGENT
@@ -2043,7 +2053,7 @@ This provides an easy way to turn it off, for performance. If this is set to
 ``False``, Django will make some optimizations so as not to load the
 translation machinery.
 
-See also :setting:`USE_L10N`
+See also :setting:`LANGUAGE_CODE`, :setting:`USE_L10N` and :setting:`USE_TZ`.
 
 .. setting:: USE_L10N
 
@@ -2058,7 +2068,7 @@ A boolean that specifies if localized formatting of data will be enabled by
 default or not. If this is set to ``True``, e.g. Django will display numbers and
 dates using the format of the current locale.
 
-See also :setting:`USE_I18N` and :setting:`LANGUAGE_CODE`
+See also :setting:`LANGUAGE_CODE`, :setting:`USE_I18N` and :setting:`USE_TZ`.
 
 .. note::
 
@@ -2082,6 +2092,26 @@ When :setting:`USE_L10N` is set to ``True`` and if this is also set to
 See also :setting:`DECIMAL_SEPARATOR`, :setting:`NUMBER_GROUPING` and
 :setting:`THOUSAND_SEPARATOR`.
 
+.. setting:: USE_TZ
+
+USE_TZ
+------
+
+.. versionadded:: 1.4
+
+Default: ``False``
+
+A boolean that specifies if datetimes will be timezone-aware by default or not.
+If this is set to ``True``, Django will use timezone-aware datetimes internally.
+Otherwise, Django will use naive datetimes in local time.
+
+See also :setting:`TIME_ZONE`, :setting:`USE_I18N` and :setting:`USE_L10N`.
+
+.. note::
+    The default :file:`settings.py` file created by
+    :djadmin:`django-admin.py startproject <startproject>` includes
+    ``USE_TZ = True`` for convenience.
+
 .. setting:: USE_X_FORWARDED_HOST
 
 USE_X_FORWARDED_HOST
diff --git a/docs/ref/templates/builtins.txt b/docs/ref/templates/builtins.txt
index 7b305746ab..695a21296b 100644
--- a/docs/ref/templates/builtins.txt
+++ b/docs/ref/templates/builtins.txt
@@ -2318,8 +2318,45 @@ Value       Argument                Outputs
                                     if no mapping for None is given)
 ==========  ======================  ==================================
 
-Other tags and filter libraries
--------------------------------
+Internationalization tags and filters
+-------------------------------------
+
+Django provides template tags and filters to control each aspect of
+`internationalization </topics/i18n/index>`_ in templates. They allow for
+granular control of translations, formatting, and time zone conversions.
+
+i18n
+^^^^
+
+This library allows specifying translatable text in templates.
+To enable it, set :setting:`USE_I18N` to ``True``, then load it with
+``{% load i18n %}``.
+
+See :ref:`specifying-translation-strings-in-template-code`.
+
+l10n
+^^^^
+
+This library provides control over the localization of values in templates.
+You only need to load the library using ``{% load l10n %}``, but you'll often
+set :setting:`USE_L10N` to ``True`` so that localization is active by default.
+
+See :ref:`topic-l10n-templates`.
+
+tz
+^^
+
+.. versionadded:: 1.4
+
+This library provides control over time zone conversions in templates.
+Like ``l10n``, you only need to load the library using ``{% load tz %}``,
+but you'll usually also set :setting:`USE_TZ` to ``True`` so that conversion
+to local time happens by default.
+
+See :ref:`time-zones-in-templates`.
+
+Other tags and filters libraries
+--------------------------------
 
 Django comes with a couple of other template-tag libraries that you have to
 enable explicitly in your :setting:`INSTALLED_APPS` setting and enable in your
@@ -2348,28 +2385,6 @@ django.contrib.webdesign
 A collection of template tags that can be useful while designing a Web site,
 such as a generator of Lorem Ipsum text. See :doc:`/ref/contrib/webdesign`.
 
-i18n
-^^^^
-
-Provides a couple of templatetags that allow specifying translatable text in
-Django templates. It is slightly different from the libraries described
-above because you don't need to add any application to the
-:setting:`INSTALLED_APPS` setting but rather set :setting:`USE_I18N` to True,
-then loading it with ``{% load i18n %}``.
-
-See :ref:`specifying-translation-strings-in-template-code`.
-
-l10n
-^^^^
-
-Provides a couple of templatetags that allow control over the localization of
-values in Django templates. It is slightly different from the libraries
-described above because you don't need to add any application to the
-:setting:`INSTALLED_APPS`; you only need to load the library using
-``{% load l10n %}``.
-
-See :ref:`topic-l10n-templates`.
-
 static
 ^^^^^^
 
diff --git a/docs/ref/utils.txt b/docs/ref/utils.txt
index 0d6e9c6b61..9a9adba0d8 100644
--- a/docs/ref/utils.txt
+++ b/docs/ref/utils.txt
@@ -131,6 +131,41 @@ results. Instead do::
 
     SortedDict([('b', 1), ('a', 2), ('c', 3)])
 
+``django.utils.dateparse``
+==========================
+
+.. versionadded:: 1.4
+
+.. module:: django.utils.dateparse
+   :synopsis: Functions to parse datetime objects.
+
+The functions defined in this module share the following properties:
+
+- They raise :exc:`ValueError` if their input is well formatted but isn't a
+  valid date or time.
+- They return ``None`` if it isn't well formatted at all.
+- They accept up to picosecond resolution in input, but they truncate it to
+  microseconds, since that's what Python supports.
+
+.. function:: parse_date(value)
+
+    Parses a string and returns a :class:`datetime.date`.
+
+.. function:: parse_time(value)
+
+    Parses a string and returns a :class:`datetime.time`.
+
+    UTC offsets aren't supported; if ``value`` describes one, the result is
+    ``None``.
+
+.. function:: parse_datetime(value)
+
+    Parses a string and returns a :class:`datetime.datetime`.
+
+    UTC offsets are supported; if ``value`` describes one, the result's
+    ``tzinfo`` attribute is a :class:`~django.utils.tzinfo.FixedOffset`
+    instance.
+
 ``django.utils.encoding``
 =========================
 
@@ -573,6 +608,96 @@ For a complete discussion on the usage of the following see the
     so by translating the Django translation tags into standard gettext function
     invocations.
 
+.. _time-zone-selection-functions:
+
+``django.utils.timezone``
+=========================
+
+.. versionadded:: 1.4
+
+.. module:: django.utils.timezone
+    :synopsis: Timezone support.
+
+.. data:: utc
+
+    :class:`~datetime.tzinfo` instance that represents UTC.
+
+.. function:: get_default_timezone()
+
+    Returns a :class:`~datetime.tzinfo` instance that represents the
+    :ref:`default time zone <default-current-time-zone>`.
+
+.. function:: get_default_timezone_name()
+
+    Returns the name of the :ref:`default time zone
+    <default-current-time-zone>`.
+
+.. function:: get_current_timezone()
+
+    Returns a :class:`~datetime.tzinfo` instance that represents the
+    :ref:`current time zone <default-current-time-zone>`.
+
+.. function:: get_current_timezone_name()
+
+    Returns the name of the :ref:`current time zone
+    <default-current-time-zone>`.
+
+.. function:: activate(timezone)
+
+    Sets the :ref:`current time zone <default-current-time-zone>`. The
+    ``timezone`` argument must be an instance of a :class:`~datetime.tzinfo`
+    subclass or, if pytz_ is available, a time zone name.
+
+.. function:: deactivate()
+
+    Unsets the :ref:`current time zone <default-current-time-zone>`.
+
+.. function:: override(timezone)
+
+    This is a Python context manager that sets the :ref:`current time zone
+    <default-current-time-zone>` on entry with :func:`activate()`, and restores
+    the previously active time zone on exit. If the ``timezone`` argument is
+    ``None``, the :ref:`current time zone <default-current-time-zone>` is unset
+    on entry with :func:`deactivate()` instead.
+
+.. function:: aslocaltime(value, use_tz=None)
+
+    This function is used by the template engine to convert datetimes to local
+    time where appropriate.
+
+.. function:: now()
+
+    Returns an aware or naive :class:`~datetime.datetime` that represents the
+    current point in time when :setting:`USE_TZ` is ``True`` or ``False``
+    respectively.
+
+.. function:: is_aware(value)
+
+    Returns ``True`` if ``value`` is aware, ``False`` if it is naive. This
+    function assumes that ``value`` is a :class:`~datetime.datetime`.
+
+.. function:: is_naive(value)
+
+    Returns ``True`` if ``value`` is naive, ``False`` if it is aware. This
+    function assumes that ``value`` is a :class:`~datetime.datetime`.
+
+.. function:: make_aware(value, timezone)
+
+    Returns an aware :class:`~datetime.datetime` that represents the same
+    point in time as ``value`` in ``timezone``, ``value`` being a naive
+    :class:`~datetime.datetime`.
+
+    This function can raise an exception if ``value`` doesn't exist or is
+    ambiguous because of DST transitions.
+
+.. function:: make_naive(value, timezone)
+
+    Returns an naive :class:`~datetime.datetime` that represents in
+    ``timezone``  the same point in time as ``value``, ``value`` being an
+    aware :class:`~datetime.datetime`
+
+.. _pytz: http://pytz.sourceforge.net/
+
 ``django.utils.tzinfo``
 =======================