class_based_views.py

# projects/mixins.py
class ProjectMixin():
    def get_project(self):
        pass

    def get_context_data(self, **kwargs):
        kwargs['project'] = self.get_project()
        return super().get_context_data(**kwargs)


# modules/views.py
from django.utils.functional import cached_property
from django.views.generic import ListView


from . import models


class ModuleListView(ProjectMixin, ListView):
    model = models.Module

    def get_project(self):
        return self.object_list.first().project

    # Alternative
    # @property
    @cached_property
    def project(self):
        """
        Benutzung im Template:

        {{ view.project }}
        """
        return self.object_list.first().project