models.py

from django.conf import settings
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.db import models
from django.utils.translation import gettext_lazy as _


class Assignment(models.Model):
    user = models.ForeignKey("auth.User", on_delete=models.PROTECT)
    subject_ct = models.ForeignKey(ContentType, on_delete=models.PROTECT)
    subject_id = models.PositiveIntegerField()
    subject = GenericForeignKey('subject_ct', 'subject_id')

    class Meta:
        unique_together = [
            ("subject_ct", "subject_id"),
        ]


class NoteQuerySet(models.QuerySet):
    def for_user(self, user):
        notes = (
            self.filter(author=user).annotate(owner_label=models.Value(_('własne'), output_field=models.CharField()))
        )
        if user.has_perm('user.view_all_notes'):
            notes |= (
                self.exclude(author=user).annotate(owner_label=models.F('author__username'))
            )
        else:
            notes |= (
                self.exclude(author=user).filter(author__groups__name=settings.SUPER_LEXICOGRAPHS_GROUP_NAME)
                .annotate(owner_label=models.Value(_('Super'), output_field=models.CharField()))
            )
        return notes


class Note(models.Model):
    author = models.ForeignKey("auth.User", on_delete=models.PROTECT)
    subject_ct = models.ForeignKey(ContentType, on_delete=models.PROTECT)
    subject_id = models.PositiveIntegerField()
    subject = GenericForeignKey('subject_ct', 'subject_id')
    note = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True)

    objects = models.Manager.from_queryset(NoteQuerySet)()