paginator.py

import collections.abc
import inspect
import warnings
from math import ceil
from django.core.paginator import (PageNotAnInteger, EmptyPage, Page, UnorderedObjectListWarning)
from django.utils.functional import cached_property
from django.utils.inspect import method_has_no_args
from django.utils.translation import gettext_lazy as _

class sqlPaginator:

    def __init__(self, object_list, count, 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.count = int(count)
        self.allow_empty_first_page = allow_empty_first_page

    def validate_number(self, number):
        """Validate the given 1-based page number."""
        try:
            if isinstance(number, float) and not number.is_integer():
                raise ValueError
            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 get_page(self, number):
        """
        Return a valid page, even if the page argument isn't a number or isn't
        in range.
        """
        try:
            number = self.validate_number(number)
        except PageNotAnInteger:
            number = 1
        except EmptyPage:
            number = self.num_pages
        return self.page(number)

    def page(self, number):
        """Return 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, number, self)

    def _get_page(self, *args, **kwargs):
        """
        Return 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):
    #
    #     """Return the total number of objects, across all pages."""
    #     c = getattr(self.object_list, 'count', None)
    #     print("count: ", c())
    #     if callable(c) and not inspect.isbuiltin(c) and method_has_no_args(c):
    #         return c()
    #     return len(self.object_list)

    @cached_property
    def num_pages(self):
        """Return 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 ceil(hits / self.per_page)

    @property
    def page_range(self):
        """
        Return a 1-based range of pages for iterating through within
        a template for loop.
        """
        return 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
            )