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Class based daterange views.

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Erik Stein 6 years ago
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      shared/utils/views/daterange.py

553
shared/utils/views/daterange.py
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## UNFINISHED WORK IN PROGRESS
"""
Generic date range views.
Django's generic date views only deal with a single date per
model. The date range views replicate the API but deal with
a start and an end date.
"""
import datetime
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.http import Http404
from django.utils import timezone
from django.utils.encoding import force_str, force_text
from django.utils.translation import ugettext as _
from django.views.generic.base import View
from django.views.generic.detail import (
BaseDetailView, SingleObjectTemplateResponseMixin,
)
from django.views.generic.list import (
MultipleObjectMixin, MultipleObjectTemplateResponseMixin,
)
from django.views.generic.dates import (
YearMixin, MonthMixin, DayMixin, WeekMixin,
DateMixin,
)
from .. import conf, preview
if conf.USE_PREVIEW_DATETIME:
effective_datetime = preview.datetime
else:
effective_datetime = timezone.datetime
class DateRangeMixin(DateMixin):
"""
Mixin class for views manipulating date-based data.
"""
date_field = None
end_date_field = None
allow_future = False
def get_end_date_field(self):
"""
Get the name of the end date field to be used to filter by.
"""
if self.end_date_field is None:
raise ImproperlyConfigured("%s.end_date_field is required." % self.__class__.__name__)
return self.end_date_field
# Note: the following three methods only work in subclasses that also
# inherit SingleObjectMixin or MultipleObjectMixin.
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, timezone.get_current_timezone())
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}
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)
context.update(extra_context)
return self.render_to_response(context)
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):
"""
Returns the field or fields to use for ordering the queryset; uses the
date field by default.
"""
return self.get_date_field() if self.ordering is None else self.ordering
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 = effective_datetime.now() if self.uses_datetime_field else effective_datetime.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 = len(qs) == 0 if paginate_by is None else not qs.exists()
if is_empty:
raise Http404(_("No %(verbose_name_plural)s available") % {
'verbose_name_plural': force_text(qs.model._meta.verbose_name_plural)
})
return qs
def get_date_list_period(self):
"""
Get the aggregation period for the list of dates: 'year', 'month', or 'day'.
"""
return self.date_list_period
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:
name = force_text(queryset.model._meta.verbose_name_plural)
raise Http404(_("No %(verbose_name_plural)s available") %
{'verbose_name_plural': name})
return date_list
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, {})
class ArchiveIndexView(MultipleObjectTemplateResponseMixin, BaseArchiveIndexView):
"""
Top-level archive of date-based items.
"""
template_name_suffix = '_archive'
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
class YearArchiveView(MultipleObjectTemplateResponseMixin, BaseYearArchiveView):
"""
List of objects published in a given year.
"""
template_name_suffix = '_archive_year'
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),
})
class MonthArchiveView(MultipleObjectTemplateResponseMixin, BaseMonthArchiveView):
"""
List of objects published in a given month.
"""
template_name_suffix = '_archive_month'
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_start = {
'%W': '1',
'%U': '0',
}[week_format]
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),
})
class WeekArchiveView(MultipleObjectTemplateResponseMixin, BaseWeekArchiveView):
"""
List of objects published in a given week.
"""
template_name_suffix = '_archive_week'
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)
})
class DayArchiveView(MultipleObjectTemplateResponseMixin, BaseDayArchiveView):
"""
List of objects published on a given day.
"""
template_name_suffix = "_archive_day"
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())
class TodayArchiveView(MultipleObjectTemplateResponseMixin, BaseTodayArchiveView):
"""
List of objects published today.
"""
template_name_suffix = "_archive_day"
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(BaseDetailView, self).get_object(queryset=qs)
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='__'):
"""
Helper: 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 = delim.join((year_format, month_format, day_format))
datestr = delim.join((year, month, day))
try:
return datetime.datetime.strptime(force_str(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):
"""
Helper: 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 <= effective_datetime.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 = effective_datetime.now()
else:
now = effective_datetime.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 = effective_datetime.localtime(result)
result = result.date()
# Return the first day of the period.
return get_current(result)
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