models.py

import uuid
from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation
from django.contrib.contenttypes.models import ContentType
from django.db import models


class Site(models.Model):
    url = models.CharField(max_length=100)


class User(models.Model):
    username = models.CharField(max_length=100)
    user_avatar = models.ForeignKey(
        'Avatar',
        null=True,
        on_delete=models.PROTECT
    )


class AccessKey(models.Model):
    key = models.CharField(max_length=100)


class Profile(models.Model):
    sites = models.ManyToManyField(Site)
    user = models.OneToOneField(
        User, on_delete=models.CASCADE)
    access_key = models.ForeignKey(
        AccessKey, on_delete=models.CASCADE, null=True)


class Avatar(models.Model):
    image = models.CharField(max_length=100)
    profile = models.ForeignKey(
        Profile, on_delete=models.CASCADE, related_name='avatars',)


class Tag(models.Model):
    tag = models.SlugField()
    content_type = models.ForeignKey(
        ContentType,
        on_delete=models.CASCADE
    )
    object_id = models.PositiveIntegerField()
    content_object = GenericForeignKey()


class TaggedItem(models.Model):
    tags = GenericRelation(Tag)


class Team(models.Model):
    name = models.CharField(max_length=100)
    members = models.ManyToManyField(User)


class CustomPK(models.Model):
    slug = models.SlugField(
        unique=True
    )
    user = models.ForeignKey(
        User,
        on_delete=models.CASCADE,
        related_name='custompks',
    )


class AbstractMessage(models.Model):
    id = models.UUIDField(
        primary_key=True,
        default=uuid.uuid4,
        editable=False
    )
    message = models.CharField(max_length=100)

    class Meta:
        abstract = True


class Message(AbstractMessage):
    profile = models.ForeignKey(Profile, on_delete=models.CASCADE)


class PersistentMessage(AbstractMessage):
    profile = models.ForeignKey(Profile, on_delete=models.CASCADE, null=True)


class AnotherProfile(models.Model):
    sites = models.ManyToManyField(Site)
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    access_key = models.ForeignKey(
        AccessKey, on_delete=models.CASCADE, null=True)


class AnotherAvatar(models.Model):
    image = models.CharField(max_length=100)
    profile = models.ForeignKey(
        AnotherProfile, on_delete=models.CASCADE, related_name='avatars',)


class Page(models.Model):
    title = models.CharField(max_length=80)


class Document(models.Model):
    page = models.ForeignKey(Page, on_delete=models.CASCADE)
    source = models.FileField()


# Models for UniqueFieldsMixin

class UFMChild(models.Model):
    field = models.CharField(max_length=50, unique=True)


class UFMParent(models.Model):
    child = models.ForeignKey(UFMChild, on_delete=models.CASCADE)


# Models for different relations

class ForeignKeyChild(models.Model):
    pass


class ForeignKeyParent(models.Model):
    child = models.ForeignKey(ForeignKeyChild,
                              on_delete=models.CASCADE,
                              related_name='parents')


class OneToOneChild(models.Model):
    pass


class OneToOneParent(models.Model):
    child = models.OneToOneField(OneToOneChild,
                                 on_delete=models.CASCADE,
                                 related_name='parent')


class ManyToManyChild(models.Model):
    pass


class ManyToManyParent(models.Model):
    children = models.ManyToManyField(ManyToManyChild, related_name='parents')


class I86Name(models.Model):
    string = models.TextField()
    item = models.ForeignKey(
        'I86Genre', on_delete=models.CASCADE, related_name='names', 
        blank=True, null=True)


class I86Genre(models.Model):
    pass