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import collections
import warnings
from math import ceil
from django.utils import six
from django.utils.functional import cached_property
from django.utils.translation import ugettext_lazy as _
class UnorderedObjectListWarning(RuntimeWarning):
pass
class InvalidPage(Exception):
pass
class PageNotAnInteger(InvalidPage):
pass
class EmptyPage(InvalidPage):
pass
class Paginator(object):
def __init__(self, object_list, per_page, orphans=0,
allow_empty_first_page=True):
self.object_list = object_list
self._check_object_list_is_ordered()
self.per_page = int(per_page)
self.orphans = int(orphans)
self.allow_empty_first_page = allow_empty_first_page
def validate_number(self, number):
"""
Validates the given 1-based page number.
"""
try:
number = int(number)
except (TypeError, ValueError):
raise PageNotAnInteger(_('That page number is not an integer'))
if number < 1:
raise EmptyPage(_('That page number is less than 1'))
if number > self.num_pages:
if number == 1 and self.allow_empty_first_page:
pass
else:
raise EmptyPage(_('That page contains no results'))
return number
def page(self, number):
"""
Returns a Page object for the given 1-based page number.
"""
number = self.validate_number(number)
bottom = (number - 1) * self.per_page
top = bottom + self.per_page
if top + self.orphans >= self.count:
top = self.count
return self._get_page(self.object_list[bottom:top], number, self)
def _get_page(self, *args, **kwargs):
"""
Returns an instance of a single page.
This hook can be used by subclasses to use an alternative to the
standard :cls:`Page` object.
"""
return Page(*args, **kwargs)
@cached_property
def count(self):
"""
Returns the total number of objects, across all pages.
"""
try:
return self.object_list.count()
except (AttributeError, TypeError):
# AttributeError if object_list has no count() method.
# TypeError if object_list.count() requires arguments
# (i.e. is of type list).
return len(self.object_list)
@cached_property
def num_pages(self):
"""
Returns the total number of pages.
"""
if self.count == 0 and not self.allow_empty_first_page:
return 0
hits = max(1, self.count - self.orphans)
return int(ceil(hits / float(self.per_page)))
@property
def page_range(self):
"""
Returns a 1-based range of pages for iterating through within
a template for loop.
"""
return six.moves.range(1, self.num_pages + 1)
def _check_object_list_is_ordered(self):
"""
Warn if self.object_list is unordered (typically a QuerySet).
"""
ordered = getattr(self.object_list, 'ordered', None)
if ordered is not None and not ordered:
obj_list_repr = (
'{} {}'.format(self.object_list.model, self.object_list.__class__.__name__)
if hasattr(self.object_list, 'model')
else '{!r}'.format(self.object_list)
)
warnings.warn(
'Pagination may yield inconsistent results with an unordered '
'object_list: {}.'.format(obj_list_repr),
UnorderedObjectListWarning,
stacklevel=3
)
QuerySetPaginator = Paginator # For backwards-compatibility.
class Page(collections.Sequence):
def __init__(self, object_list, number, paginator):
self.object_list = object_list
self.number = number
self.paginator = paginator
def __repr__(self):
return '<Page %s of %s>' % (self.number, self.paginator.num_pages)
def __len__(self):
return len(self.object_list)
def __getitem__(self, index):
if not isinstance(index, (slice,) + six.integer_types):
raise TypeError
# The object_list is converted to a list so that if it was a QuerySet
# it won't be a database hit per __getitem__.
if not isinstance(self.object_list, list):
self.object_list = list(self.object_list)
return self.object_list[index]
def has_next(self):
return self.number < self.paginator.num_pages
def has_previous(self):
return self.number > 1
def has_other_pages(self):
return self.has_previous() or self.has_next()
def next_page_number(self):
return self.paginator.validate_number(self.number + 1)
def previous_page_number(self):
return self.paginator.validate_number(self.number - 1)
def start_index(self):
"""
Returns the 1-based index of the first object on this page,
relative to total objects in the paginator.
"""
# Special case, return zero if no items.
if self.paginator.count == 0:
return 0
return (self.paginator.per_page * (self.number - 1)) + 1
def end_index(self):
"""
Returns the 1-based index of the last object on this page,
relative to total objects found (hits).
"""
# Special case for the last page because there can be orphans.
if self.number == self.paginator.num_pages:
return self.paginator.count
return self.number * self.paginator.per_page
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