simple_pagination.py

from math import ceil

class Pagination(object):
    """A Pagination object to be used for querying and displaying pagination links on frontend

    Example usage:

    >>> p = Pagination(total=15, per_page=5, current_page=1, side_page_num=3)
    >>> p.start
    0
    >>> p.pages
    [1, 2, 3]
    >>> p.next_page
    2
    >>> p.current_page = 2
    >>> p.prev_page
    1
    >>> p.next_page
    3
    >>> p.start
    5

    :copyright: (c) 2013 James Morris http://jmoz.co.uk.
    :update: (c) 2015 Jackwei https://github.com/ego008
    """

    def __init__(self, total=None, per_page=100, current_page=1, side_page_num=3):
        """init with total number of items in your set, how many you want per_page, and set the current_page you are on"""
        self.total = total
        self.per_page = per_page
        self.current_page = current_page
        self.side_page_num = side_page_num

    def __repr__(self):
        return str(self.__dict__)

    @property
    def total_pages(self):
        """The number of pages this pagination can have due to the total and per_page, e.g. total 10, per_page 5 = 2 total_pages
        Cast to float so result is float, round up, then back to int
        """
        return int(ceil(float(self.total) / self.per_page))

    @property
    def pages(self):
        """Returns list of integers of pages e.g. for 3 pages [1,2,3]"""

        if 0 < self.current_page <= self.total_pages:
            show_page_num = self.side_page_num * 2 + 1

            from_page = self.current_page - self.side_page_num
            if from_page < 1:
                from_page = 1
            to_page = from_page + show_page_num - 1
            if to_page > self.total_pages:
                to_page = self.total_pages
            if to_page >= show_page_num and (to_page - from_page) < (show_page_num - 1):
                from_page = to_page - show_page_num + 1
            return range(from_page, to_page+1)

        return []

    @property
    def next_page(self):
        """The page number after the current_page or None"""
        return self._get_page_offset(+1)

    @property
    def prev_page(self):
        """The page number before the current_page or None"""
        return self._get_page_offset(-1)

    def _get_page_offset(self, offset):
        """Give an offset, +1 or -1 and the page number around the current_page will be returned
        So if we are on current_page 2 and pass +1 we get 3, if we pass -1 we get 1.  Or None if not valid
        """
        try:
            return self.pages[self.pages.index(self.current_page + offset)]
        except ValueError:
            return None

    @property
    def start(self):
        """The starting offset used when querying"""
        return self.current_page * self.per_page - self.per_page