166 lines
5.1 KiB
Python
166 lines
5.1 KiB
Python
import collections
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import warnings
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from math import ceil
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from django.utils.functional import cached_property
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from django.utils.translation import gettext_lazy as _
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class UnorderedObjectListWarning(RuntimeWarning):
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pass
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class InvalidPage(Exception):
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pass
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class PageNotAnInteger(InvalidPage):
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pass
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class EmptyPage(InvalidPage):
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pass
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class Paginator:
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def __init__(self, object_list, per_page, orphans=0,
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allow_empty_first_page=True):
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self.object_list = object_list
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self._check_object_list_is_ordered()
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self.per_page = int(per_page)
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self.orphans = int(orphans)
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self.allow_empty_first_page = allow_empty_first_page
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def validate_number(self, number):
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"""Validate the given 1-based page number."""
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try:
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number = int(number)
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except (TypeError, ValueError):
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raise PageNotAnInteger(_('That page number is not an integer'))
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if number < 1:
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raise EmptyPage(_('That page number is less than 1'))
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if number > self.num_pages:
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if number == 1 and self.allow_empty_first_page:
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pass
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else:
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raise EmptyPage(_('That page contains no results'))
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return number
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def page(self, number):
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"""Return a Page object for the given 1-based page number."""
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number = self.validate_number(number)
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bottom = (number - 1) * self.per_page
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top = bottom + self.per_page
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if top + self.orphans >= self.count:
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top = self.count
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return self._get_page(self.object_list[bottom:top], number, self)
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def _get_page(self, *args, **kwargs):
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"""
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Return an instance of a single page.
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This hook can be used by subclasses to use an alternative to the
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standard :cls:`Page` object.
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"""
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return Page(*args, **kwargs)
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@cached_property
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def count(self):
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"""Return the total number of objects, across all pages."""
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try:
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return self.object_list.count()
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except (AttributeError, TypeError):
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# AttributeError if object_list has no count() method.
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# TypeError if object_list.count() requires arguments
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# (i.e. is of type list).
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return len(self.object_list)
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@cached_property
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def num_pages(self):
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"""Return the total number of pages."""
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if self.count == 0 and not self.allow_empty_first_page:
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return 0
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hits = max(1, self.count - self.orphans)
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return int(ceil(hits / float(self.per_page)))
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@property
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def page_range(self):
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"""
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Return a 1-based range of pages for iterating through within
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a template for loop.
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"""
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return range(1, self.num_pages + 1)
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def _check_object_list_is_ordered(self):
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"""
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Warn if self.object_list is unordered (typically a QuerySet).
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"""
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if hasattr(self.object_list, 'ordered') and not self.object_list.ordered:
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warnings.warn(
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'Pagination may yield inconsistent results with an unordered '
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'object_list: {!r}'.format(self.object_list),
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UnorderedObjectListWarning
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)
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QuerySetPaginator = Paginator # For backwards-compatibility.
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class Page(collections.Sequence):
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def __init__(self, object_list, number, paginator):
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self.object_list = object_list
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self.number = number
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self.paginator = paginator
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def __repr__(self):
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return '<Page %s of %s>' % (self.number, self.paginator.num_pages)
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def __len__(self):
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return len(self.object_list)
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def __getitem__(self, index):
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if not isinstance(index, (int, slice)):
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raise TypeError
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# The object_list is converted to a list so that if it was a QuerySet
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# it won't be a database hit per __getitem__.
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if not isinstance(self.object_list, list):
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self.object_list = list(self.object_list)
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return self.object_list[index]
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def has_next(self):
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return self.number < self.paginator.num_pages
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def has_previous(self):
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return self.number > 1
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def has_other_pages(self):
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return self.has_previous() or self.has_next()
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def next_page_number(self):
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return self.paginator.validate_number(self.number + 1)
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def previous_page_number(self):
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return self.paginator.validate_number(self.number - 1)
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def start_index(self):
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"""
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Return the 1-based index of the first object on this page,
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relative to total objects in the paginator.
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"""
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# Special case, return zero if no items.
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if self.paginator.count == 0:
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return 0
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return (self.paginator.per_page * (self.number - 1)) + 1
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def end_index(self):
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"""
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Return the 1-based index of the last object on this page,
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relative to total objects found (hits).
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"""
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# Special case for the last page because there can be orphans.
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if self.number == self.paginator.num_pages:
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return self.paginator.count
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return self.number * self.paginator.per_page
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