import datetime
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.db import models
from django.http import Http404
from django.utils import timezone
from django.utils.functional import cached_property
from django.utils.translation import gettext as _
from django.views.generic.base import View
from django.views.generic.detail import (
BaseDetailView, SingleObjectTemplateResponseMixin,
)
from django.views.generic.list import (
MultipleObjectMixin, MultipleObjectTemplateResponseMixin,
)
[docs]class YearMixin:
"""Mixin for views manipulating year-based data."""
year_format = '%Y'
year = None
[docs] def get_year_format(self):
"""
Get a year format string in strptime syntax to be used to parse the
year from url variables.
"""
return self.year_format
[docs] def get_year(self):
"""Return the year for which this view should display data."""
year = self.year
if year is None:
try:
year = self.kwargs['year']
except KeyError:
try:
year = self.request.GET['year']
except KeyError:
raise Http404(_("No year specified"))
return year
[docs] def get_next_year(self, date):
"""Get the next valid year."""
return _get_next_prev(self, date, is_previous=False, period='year')
[docs] def get_previous_year(self, date):
"""Get the previous valid year."""
return _get_next_prev(self, date, is_previous=True, period='year')
def _get_next_year(self, date):
"""
Return the start date of the next interval.
The interval is defined by start date <= item date < next start date.
"""
try:
return date.replace(year=date.year + 1, month=1, day=1)
except ValueError:
raise Http404(_("Date out of range"))
def _get_current_year(self, date):
"""Return the start date of the current interval."""
return date.replace(month=1, day=1)
[docs]class MonthMixin:
"""Mixin for views manipulating month-based data."""
month_format = '%b'
month = None
[docs] def get_month_format(self):
"""
Get a month format string in strptime syntax to be used to parse the
month from url variables.
"""
return self.month_format
[docs] def get_month(self):
"""Return the month for which this view should display data."""
month = self.month
if month is None:
try:
month = self.kwargs['month']
except KeyError:
try:
month = self.request.GET['month']
except KeyError:
raise Http404(_("No month specified"))
return month
[docs] def get_next_month(self, date):
"""Get the next valid month."""
return _get_next_prev(self, date, is_previous=False, period='month')
[docs] def get_previous_month(self, date):
"""Get the previous valid month."""
return _get_next_prev(self, date, is_previous=True, period='month')
def _get_next_month(self, date):
"""
Return the start date of the next interval.
The interval is defined by start date <= item date < next start date.
"""
if date.month == 12:
try:
return date.replace(year=date.year + 1, month=1, day=1)
except ValueError:
raise Http404(_("Date out of range"))
else:
return date.replace(month=date.month + 1, day=1)
def _get_current_month(self, date):
"""Return the start date of the previous interval."""
return date.replace(day=1)
[docs]class DayMixin:
"""Mixin for views manipulating day-based data."""
day_format = '%d'
day = None
[docs] def get_day_format(self):
"""
Get a day format string in strptime syntax to be used to parse the day
from url variables.
"""
return self.day_format
[docs] def get_day(self):
"""Return the day for which this view should display data."""
day = self.day
if day is None:
try:
day = self.kwargs['day']
except KeyError:
try:
day = self.request.GET['day']
except KeyError:
raise Http404(_("No day specified"))
return day
[docs] def get_next_day(self, date):
"""Get the next valid day."""
return _get_next_prev(self, date, is_previous=False, period='day')
[docs] def get_previous_day(self, date):
"""Get the previous valid day."""
return _get_next_prev(self, date, is_previous=True, period='day')
def _get_next_day(self, date):
"""
Return the start date of the next interval.
The interval is defined by start date <= item date < next start date.
"""
return date + datetime.timedelta(days=1)
def _get_current_day(self, date):
"""Return the start date of the current interval."""
return date
[docs]class WeekMixin:
"""Mixin for views manipulating week-based data."""
week_format = '%U'
week = None
[docs] def get_week_format(self):
"""
Get a week format string in strptime syntax to be used to parse the
week from url variables.
"""
return self.week_format
[docs] def get_week(self):
"""Return the week for which this view should display data."""
week = self.week
if week is None:
try:
week = self.kwargs['week']
except KeyError:
try:
week = self.request.GET['week']
except KeyError:
raise Http404(_("No week specified"))
return week
[docs] def get_next_week(self, date):
"""Get the next valid week."""
return _get_next_prev(self, date, is_previous=False, period='week')
def get_previous_week(self, date):
"""Get the previous valid week."""
return _get_next_prev(self, date, is_previous=True, period='week')
def _get_next_week(self, date):
"""
Return the start date of the next interval.
The interval is defined by start date <= item date < next start date.
"""
try:
return date + datetime.timedelta(days=7 - self._get_weekday(date))
except OverflowError:
raise Http404(_("Date out of range"))
def _get_current_week(self, date):
"""Return the start date of the current interval."""
return date - datetime.timedelta(self._get_weekday(date))
def _get_weekday(self, date):
"""
Return the weekday for a given date.
The first day according to the week format is 0 and the last day is 6.
"""
week_format = self.get_week_format()
if week_format == '%W': # week starts on Monday
return date.weekday()
elif week_format == '%U': # week starts on Sunday
return (date.weekday() + 1) % 7
else:
raise ValueError("unknown week format: %s" % week_format)
[docs]class DateMixin:
"""Mixin class for views manipulating date-based data."""
date_field = None
allow_future = False
[docs] def get_date_field(self):
"""Get the name of the date field to be used to filter by."""
if self.date_field is None:
raise ImproperlyConfigured("%s.date_field is required." % self.__class__.__name__)
return self.date_field
[docs] def get_allow_future(self):
"""
Return `True` if the view should be allowed to display objects from
the future.
"""
return self.allow_future
# Note: the following three methods only work in subclasses that also
# inherit SingleObjectMixin or MultipleObjectMixin.
@cached_property
def uses_datetime_field(self):
"""
Return `True` if the date field is a `DateTimeField` and `False`
if it's a `DateField`.
"""
model = self.get_queryset().model if self.model is None else self.model
field = model._meta.get_field(self.get_date_field())
return isinstance(field, models.DateTimeField)
def _make_date_lookup_arg(self, value):
"""
Convert a date into a datetime when the date field is a DateTimeField.
When time zone support is enabled, `date` is assumed to be in the
current time zone, so that displayed items are consistent with the URL.
"""
if self.uses_datetime_field:
value = datetime.datetime.combine(value, datetime.time.min)
if settings.USE_TZ:
value = timezone.make_aware(value)
return value
def _make_single_date_lookup(self, date):
"""
Get the lookup kwargs for filtering on a single date.
If the date field is a DateTimeField, we can't just filter on
date_field=date because that doesn't take the time into account.
"""
date_field = self.get_date_field()
if self.uses_datetime_field:
since = self._make_date_lookup_arg(date)
until = self._make_date_lookup_arg(date + datetime.timedelta(days=1))
return {
'%s__gte' % date_field: since,
'%s__lt' % date_field: until,
}
else:
# Skip self._make_date_lookup_arg, it's a no-op in this branch.
return {date_field: date}
[docs]class BaseDateListView(MultipleObjectMixin, DateMixin, View):
"""Abstract base class for date-based views displaying a list of objects."""
allow_empty = False
date_list_period = 'year'
def get(self, request, *args, **kwargs):
self.date_list, self.object_list, extra_context = self.get_dated_items()
context = self.get_context_data(
object_list=self.object_list,
date_list=self.date_list,
**extra_context
)
return self.render_to_response(context)
[docs] def get_dated_items(self):
"""Obtain the list of dates and items."""
raise NotImplementedError('A DateView must provide an implementation of get_dated_items()')
def get_ordering(self):
"""
Return the field or fields to use for ordering the queryset; use the
date field by default.
"""
return '-%s' % self.get_date_field() if self.ordering is None else self.ordering
[docs] def get_dated_queryset(self, **lookup):
"""
Get a queryset properly filtered according to `allow_future` and any
extra lookup kwargs.
"""
qs = self.get_queryset().filter(**lookup)
date_field = self.get_date_field()
allow_future = self.get_allow_future()
allow_empty = self.get_allow_empty()
paginate_by = self.get_paginate_by(qs)
if not allow_future:
now = timezone.now() if self.uses_datetime_field else timezone_today()
qs = qs.filter(**{'%s__lte' % date_field: now})
if not allow_empty:
# When pagination is enabled, it's better to do a cheap query
# than to load the unpaginated queryset in memory.
is_empty = not qs if paginate_by is None else not qs.exists()
if is_empty:
raise Http404(_("No %(verbose_name_plural)s available") % {
'verbose_name_plural': qs.model._meta.verbose_name_plural,
})
return qs
[docs] def get_date_list_period(self):
"""
Get the aggregation period for the list of dates: 'year', 'month', or
'day'.
"""
return self.date_list_period
[docs] def get_date_list(self, queryset, date_type=None, ordering='ASC'):
"""
Get a date list by calling `queryset.dates/datetimes()`, checking
along the way for empty lists that aren't allowed.
"""
date_field = self.get_date_field()
allow_empty = self.get_allow_empty()
if date_type is None:
date_type = self.get_date_list_period()
if self.uses_datetime_field:
date_list = queryset.datetimes(date_field, date_type, ordering)
else:
date_list = queryset.dates(date_field, date_type, ordering)
if date_list is not None and not date_list and not allow_empty:
raise Http404(
_("No %(verbose_name_plural)s available") % {
'verbose_name_plural': queryset.model._meta.verbose_name_plural,
}
)
return date_list
[docs]class BaseArchiveIndexView(BaseDateListView):
"""
Base class for archives of date-based items. Requires a response mixin.
"""
context_object_name = 'latest'
def get_dated_items(self):
"""Return (date_list, items, extra_context) for this request."""
qs = self.get_dated_queryset()
date_list = self.get_date_list(qs, ordering='DESC')
if not date_list:
qs = qs.none()
return (date_list, qs, {})
[docs]class ArchiveIndexView(MultipleObjectTemplateResponseMixin, BaseArchiveIndexView):
"""Top-level archive of date-based items."""
template_name_suffix = '_archive'
[docs]class BaseYearArchiveView(YearMixin, BaseDateListView):
"""List of objects published in a given year."""
date_list_period = 'month'
make_object_list = False
def get_dated_items(self):
"""Return (date_list, items, extra_context) for this request."""
year = self.get_year()
date_field = self.get_date_field()
date = _date_from_string(year, self.get_year_format())
since = self._make_date_lookup_arg(date)
until = self._make_date_lookup_arg(self._get_next_year(date))
lookup_kwargs = {
'%s__gte' % date_field: since,
'%s__lt' % date_field: until,
}
qs = self.get_dated_queryset(**lookup_kwargs)
date_list = self.get_date_list(qs)
if not self.get_make_object_list():
# We need this to be a queryset since parent classes introspect it
# to find information about the model.
qs = qs.none()
return (date_list, qs, {
'year': date,
'next_year': self.get_next_year(date),
'previous_year': self.get_previous_year(date),
})
def get_make_object_list(self):
"""
Return `True` if this view should contain the full list of objects in
the given year.
"""
return self.make_object_list
[docs]class YearArchiveView(MultipleObjectTemplateResponseMixin, BaseYearArchiveView):
"""List of objects published in a given year."""
template_name_suffix = '_archive_year'
[docs]class BaseMonthArchiveView(YearMixin, MonthMixin, BaseDateListView):
"""List of objects published in a given month."""
date_list_period = 'day'
def get_dated_items(self):
"""Return (date_list, items, extra_context) for this request."""
year = self.get_year()
month = self.get_month()
date_field = self.get_date_field()
date = _date_from_string(year, self.get_year_format(),
month, self.get_month_format())
since = self._make_date_lookup_arg(date)
until = self._make_date_lookup_arg(self._get_next_month(date))
lookup_kwargs = {
'%s__gte' % date_field: since,
'%s__lt' % date_field: until,
}
qs = self.get_dated_queryset(**lookup_kwargs)
date_list = self.get_date_list(qs)
return (date_list, qs, {
'month': date,
'next_month': self.get_next_month(date),
'previous_month': self.get_previous_month(date),
})
[docs]class MonthArchiveView(MultipleObjectTemplateResponseMixin, BaseMonthArchiveView):
"""List of objects published in a given month."""
template_name_suffix = '_archive_month'
[docs]class BaseWeekArchiveView(YearMixin, WeekMixin, BaseDateListView):
"""List of objects published in a given week."""
def get_dated_items(self):
"""Return (date_list, items, extra_context) for this request."""
year = self.get_year()
week = self.get_week()
date_field = self.get_date_field()
week_format = self.get_week_format()
week_choices = {'%W': '1', '%U': '0'}
try:
week_start = week_choices[week_format]
except KeyError:
raise ValueError('Unknown week format %r. Choices are: %s' % (
week_format,
', '.join(sorted(week_choices)),
))
date = _date_from_string(year, self.get_year_format(),
week_start, '%w',
week, week_format)
since = self._make_date_lookup_arg(date)
until = self._make_date_lookup_arg(self._get_next_week(date))
lookup_kwargs = {
'%s__gte' % date_field: since,
'%s__lt' % date_field: until,
}
qs = self.get_dated_queryset(**lookup_kwargs)
return (None, qs, {
'week': date,
'next_week': self.get_next_week(date),
'previous_week': self.get_previous_week(date),
})
[docs]class WeekArchiveView(MultipleObjectTemplateResponseMixin, BaseWeekArchiveView):
"""List of objects published in a given week."""
template_name_suffix = '_archive_week'
[docs]class BaseDayArchiveView(YearMixin, MonthMixin, DayMixin, BaseDateListView):
"""List of objects published on a given day."""
def get_dated_items(self):
"""Return (date_list, items, extra_context) for this request."""
year = self.get_year()
month = self.get_month()
day = self.get_day()
date = _date_from_string(year, self.get_year_format(),
month, self.get_month_format(),
day, self.get_day_format())
return self._get_dated_items(date)
def _get_dated_items(self, date):
"""
Do the actual heavy lifting of getting the dated items; this accepts a
date object so that TodayArchiveView can be trivial.
"""
lookup_kwargs = self._make_single_date_lookup(date)
qs = self.get_dated_queryset(**lookup_kwargs)
return (None, qs, {
'day': date,
'previous_day': self.get_previous_day(date),
'next_day': self.get_next_day(date),
'previous_month': self.get_previous_month(date),
'next_month': self.get_next_month(date)
})
[docs]class DayArchiveView(MultipleObjectTemplateResponseMixin, BaseDayArchiveView):
"""List of objects published on a given day."""
template_name_suffix = "_archive_day"
[docs]class BaseTodayArchiveView(BaseDayArchiveView):
"""List of objects published today."""
def get_dated_items(self):
"""Return (date_list, items, extra_context) for this request."""
return self._get_dated_items(datetime.date.today())
[docs]class TodayArchiveView(MultipleObjectTemplateResponseMixin, BaseTodayArchiveView):
"""List of objects published today."""
template_name_suffix = "_archive_day"
[docs]class BaseDateDetailView(YearMixin, MonthMixin, DayMixin, DateMixin, BaseDetailView):
"""
Detail view of a single object on a single date; this differs from the
standard DetailView by accepting a year/month/day in the URL.
"""
def get_object(self, queryset=None):
"""Get the object this request displays."""
year = self.get_year()
month = self.get_month()
day = self.get_day()
date = _date_from_string(year, self.get_year_format(),
month, self.get_month_format(),
day, self.get_day_format())
# Use a custom queryset if provided
qs = self.get_queryset() if queryset is None else queryset
if not self.get_allow_future() and date > datetime.date.today():
raise Http404(_(
"Future %(verbose_name_plural)s not available because "
"%(class_name)s.allow_future is False."
) % {
'verbose_name_plural': qs.model._meta.verbose_name_plural,
'class_name': self.__class__.__name__,
})
# Filter down a queryset from self.queryset using the date from the
# URL. This'll get passed as the queryset to DetailView.get_object,
# which'll handle the 404
lookup_kwargs = self._make_single_date_lookup(date)
qs = qs.filter(**lookup_kwargs)
return super().get_object(queryset=qs)
[docs]class DateDetailView(SingleObjectTemplateResponseMixin, BaseDateDetailView):
"""
Detail view of a single object on a single date; this differs from the
standard DetailView by accepting a year/month/day in the URL.
"""
template_name_suffix = '_detail'
def _date_from_string(year, year_format, month='', month_format='', day='', day_format='', delim='__'):
"""
Get a datetime.date object given a format string and a year, month, and day
(only year is mandatory). Raise a 404 for an invalid date.
"""
format = year_format + delim + month_format + delim + day_format
datestr = str(year) + delim + str(month) + delim + str(day)
try:
return datetime.datetime.strptime(datestr, format).date()
except ValueError:
raise Http404(_("Invalid date string '%(datestr)s' given format '%(format)s'") % {
'datestr': datestr,
'format': format,
})
def _get_next_prev(generic_view, date, is_previous, period):
"""
Get the next or the previous valid date. The idea is to allow links on
month/day views to never be 404s by never providing a date that'll be
invalid for the given view.
This is a bit complicated since it handles different intervals of time,
hence the coupling to generic_view.
However in essence the logic comes down to:
* If allow_empty and allow_future are both true, this is easy: just
return the naive result (just the next/previous day/week/month,
regardless of object existence.)
* If allow_empty is true, allow_future is false, and the naive result
isn't in the future, then return it; otherwise return None.
* If allow_empty is false and allow_future is true, return the next
date *that contains a valid object*, even if it's in the future. If
there are no next objects, return None.
* If allow_empty is false and allow_future is false, return the next
date that contains a valid object. If that date is in the future, or
if there are no next objects, return None.
"""
date_field = generic_view.get_date_field()
allow_empty = generic_view.get_allow_empty()
allow_future = generic_view.get_allow_future()
get_current = getattr(generic_view, '_get_current_%s' % period)
get_next = getattr(generic_view, '_get_next_%s' % period)
# Bounds of the current interval
start, end = get_current(date), get_next(date)
# If allow_empty is True, the naive result will be valid
if allow_empty:
if is_previous:
result = get_current(start - datetime.timedelta(days=1))
else:
result = end
if allow_future or result <= timezone_today():
return result
else:
return None
# Otherwise, we'll need to go to the database to look for an object
# whose date_field is at least (greater than/less than) the given
# naive result
else:
# Construct a lookup and an ordering depending on whether we're doing
# a previous date or a next date lookup.
if is_previous:
lookup = {'%s__lt' % date_field: generic_view._make_date_lookup_arg(start)}
ordering = '-%s' % date_field
else:
lookup = {'%s__gte' % date_field: generic_view._make_date_lookup_arg(end)}
ordering = date_field
# Filter out objects in the future if appropriate.
if not allow_future:
# Fortunately, to match the implementation of allow_future,
# we need __lte, which doesn't conflict with __lt above.
if generic_view.uses_datetime_field:
now = timezone.now()
else:
now = timezone_today()
lookup['%s__lte' % date_field] = now
qs = generic_view.get_queryset().filter(**lookup).order_by(ordering)
# Snag the first object from the queryset; if it doesn't exist that
# means there's no next/previous link available.
try:
result = getattr(qs[0], date_field)
except IndexError:
return None
# Convert datetimes to dates in the current time zone.
if generic_view.uses_datetime_field:
if settings.USE_TZ:
result = timezone.localtime(result)
result = result.date()
# Return the first day of the period.
return get_current(result)
def timezone_today():
"""Return the current date in the current time zone."""
if settings.USE_TZ:
return timezone.localdate()
else:
return datetime.date.today()
May 01, 2019