bornhack-website/src/camps/mixins.py

from camps.models import Camp
from django.shortcuts import get_object_or_404
from django.utils.functional import cached_property


class CampViewMixin(object):
    """
    This mixin makes sure self.camp is available (taken from url kwarg camp_slug)
    It also filters out objects that belong to other camps when the queryset has
    a direct relation to the Camp model.
    """

    def dispatch(self, request, *args, **kwargs):
        self.camp = get_object_or_404(Camp, slug=self.kwargs["camp_slug"])
        return super().dispatch(request, *args, **kwargs)

    def get_queryset(self):
        queryset = super().get_queryset()

        # if this queryset is empty return it right away, because nothing for us to do
        if not queryset:
            return queryset

        # get the camp_filter from the model
        camp_filter = self.model.get_camp_filter()

        # Let us deal with eveything as a list
        if isinstance(camp_filter, str):
            camp_filter = [camp_filter]

        for _filter in camp_filter:
            # add camp to the filter_dict
            filter_dict = {_filter: self.camp}

            # get pk from kwargs if we have it
            if hasattr(self, 'pk_url_kwarg'):
                pk = self.kwargs.get(self.pk_url_kwarg)
                if pk is not None:
                    # We should also filter for the pk of the object
                    filter_dict['pk'] = pk

            # get slug from kwargs if we have it
            if hasattr(self, 'slug_url_kwarg'):
                slug = self.kwargs.get(self.slug_url_kwarg)
                if slug is not None and (pk is None or self.query_pk_and_slug):
                    # we should also filter for the slug of the object
                    filter_dict[self.get_slug_field()] = slug

            # do the filtering and return the result
            result = queryset.filter(**filter_dict)
            if result.exists():
                # we got some results with this camp_filter, return now
                return result

        # no camp_filter returned any results, return an empty queryset
        return result