copy_queryset_without_annotations: mixins

admin_mixins.py

class PaginatorWithOptimizedCount(Paginator):
    @cached_property
    def count(self):
        try:
            # First usage of optimization function
            return copy_queryset_without_annotations(self.object_list).count()
        except (AttributeError, TypeError):
            return len(self.object_list)


class ChangeListWithOptimizedCount(ChangeList):
    def get_results(self, request):
        paginator = self.model_admin.get_paginator(request, self.queryset, self.list_per_page)
        result_count = paginator.count

        if self.model_admin.show_full_result_count:
           # Seconde usage of optimization function
            full_result_count = copy_queryset_without_annotations(self.root_queryset).count()
        else:
            full_result_count = None
        can_show_all = result_count <= self.list_max_show_all
        multi_page = result_count > self.list_per_page

        if (self.show_all and can_show_all) or not multi_page:
            result_list = self.queryset._clone()
        else:
            try:
                result_list = paginator.page(self.page_num + 1).object_list
            except InvalidPage:
                raise IncorrectLookupParameters

        self.result_count = result_count
        self.show_full_result_count = self.model_admin.show_full_result_count
        self.show_admin_actions = not self.show_full_result_count or bool(full_result_count)
        self.full_result_count = full_result_count
        self.result_list = result_list
        self.can_show_all = can_show_all
        self.multi_page = multi_page
        self.paginator = paginator


class ModelAdminOptimizedMixin(object):
    def get_changelist(self, request, **kwargs):
        return ChangeListWithOptimizedCount

    def get_paginator(self, request, queryset, per_page, orphans=0, allow_empty_first_page=True):
        return PaginatorWithOptimizedCount(queryset, per_page, orphans, allow_empty_first_page)