app/django/core/paginator.py
author Sverre Rabbelier <srabbelier@gmail.com>
Mon, 16 Mar 2009 23:54:07 +0000
changeset 1905 8065fd1f3e4c
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Added seed student proposal support to seed_many Patch by: Sverre Rabbelier
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from math import ceil
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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(object):
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    def __init__(self, object_list, per_page, orphans=0, allow_empty_first_page=True):
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        self.object_list = object_list
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        self.per_page = per_page
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        self.orphans = orphans
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        self.allow_empty_first_page = allow_empty_first_page
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        self._num_pages = self._count = None
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    def validate_number(self, number):
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        "Validates the given 1-based page number."
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        try:
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            number = int(number)
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        except 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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        "Returns 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 Page(self.object_list[bottom:top], number, self)
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    def _get_count(self):
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        "Returns the total number of objects, across all pages."
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        if self._count is None:
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            try:
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                self._count = 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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                self._count = len(self.object_list)
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        return self._count
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    count = property(_get_count)
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    def _get_num_pages(self):
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        "Returns the total number of pages."
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        if self._num_pages is None:
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            if self.count == 0 and not self.allow_empty_first_page:
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                self._num_pages = 0
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            else:
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                hits = max(1, self.count - self.orphans)
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                self._num_pages = int(ceil(hits / float(self.per_page)))
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        return self._num_pages
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    num_pages = property(_get_num_pages)
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    def _get_page_range(self):
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        """
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        Returns 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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    page_range = property(_get_page_range)
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QuerySetPaginator = Paginator # For backwards-compatibility.
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class Page(object):
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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 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.number + 1
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    def previous_page_number(self):
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        return self.number - 1
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    def start_index(self):
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        """
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        Returns 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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        Returns 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