225 lines
7.3 KiB
Python
225 lines
7.3 KiB
Python
import collections.abc
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import inspect
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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.inspect import method_has_no_args
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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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# Translators: String used to replace omitted page numbers in elided page
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# range generated by paginators, e.g. [1, 2, '…', 5, 6, 7, '…', 9, 10].
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ELLIPSIS = _('…')
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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 __iter__(self):
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for page_number in self.page_range:
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yield self.page(page_number)
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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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if isinstance(number, float) and not number.is_integer():
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raise ValueError
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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 get_page(self, number):
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"""
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Return a valid page, even if the page argument isn't a number or isn't
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in range.
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"""
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try:
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number = self.validate_number(number)
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except PageNotAnInteger:
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number = 1
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except EmptyPage:
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number = self.num_pages
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return self.page(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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c = getattr(self.object_list, 'count', None)
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if callable(c) and not inspect.isbuiltin(c) and method_has_no_args(c):
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return c()
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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 ceil(hits / 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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ordered = getattr(self.object_list, 'ordered', None)
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if ordered is not None and not ordered:
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obj_list_repr = (
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'{} {}'.format(self.object_list.model, self.object_list.__class__.__name__)
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if hasattr(self.object_list, 'model')
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else '{!r}'.format(self.object_list)
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)
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warnings.warn(
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'Pagination may yield inconsistent results with an unordered '
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'object_list: {}.'.format(obj_list_repr),
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UnorderedObjectListWarning,
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stacklevel=3
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)
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def get_elided_page_range(self, number=1, *, on_each_side=3, on_ends=2):
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"""
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Return a 1-based range of pages with some values elided.
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If the page range is larger than a given size, the whole range is not
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provided and a compact form is returned instead, e.g. for a paginator
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with 50 pages, if page 43 were the current page, the output, with the
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default arguments, would be:
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1, 2, …, 40, 41, 42, 43, 44, 45, 46, …, 49, 50.
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"""
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number = self.validate_number(number)
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if self.num_pages <= (on_each_side + on_ends) * 2:
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yield from self.page_range
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return
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if number > (1 + on_each_side + on_ends) + 1:
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yield from range(1, on_ends + 1)
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yield self.ELLIPSIS
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yield from range(number - on_each_side, number + 1)
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else:
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yield from range(1, number + 1)
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if number < (self.num_pages - on_each_side - on_ends) - 1:
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yield from range(number + 1, number + on_each_side + 1)
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yield self.ELLIPSIS
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yield from range(self.num_pages - on_ends + 1, self.num_pages + 1)
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else:
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yield from range(number + 1, self.num_pages + 1)
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class Page(collections.abc.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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'Page indices must be integers or slices, not %s.'
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% type(index).__name__
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)
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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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