from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
 
class Note(models.Model): #Note
    Target_Type = models.ForeignKey(ContentType)             
    TargetId = models.PositiveIntegerField()    
    ToTarget = GenericForeignKey('Target_Type', 'TargetId')

Note(ToTarget=User.objects.get(username='Mima'))

class MyBaseModel(models.Model):
    class Meta:
        abstract = True    # данное поле указывает, что класс абстрактный

class Comment(PostBase):
    class Meta:
        db_table = "comments"
 
    article = models.ForeignKey(Article)

#класс музыкант:
class Person(models.Model):
     name = models.CharField(max_length=128)
 
     def __unicode__(self):
          return self.name
 
#класс группа:
class Group(models.Model):
    name = models.CharField(max_length=128)
    members = models.ManyToManyField(Person, through='Membership')
 
    def __unicode__(self):
        return self.name
 
class Membership(models.Model):
    person = models.ForeignKey(Person)
    group = models.ForeignKey(Group)
    date_joined = models.DateField()
    invite_reason = models.CharField(max_length=64)

ringo = Person.objects.create(name="Ringo Starr")
paul = Person.objects.create(name="Paul McCartney")
beatles = Group.objects.create(name="The Beatles")
m1 = Membership(person=ringo, 
   group=beatles,
   date_joined=date(1962, 8, 16),
   invite_reason= "Needed a new drummer.")
m1.save()
print(beatles.members.all())

print(ringo.group_set.all())

m2 = Membership.objects.create(person=paul, group=beatles,
    date_joined=date(1960, 8, 1),
    invite_reason= "Wanted to form a band.")
print(beatles.members.all())

# это не будет работать:
beatles.members.add(john)
# NEITHER WILL THIS
beatles.members.create(name="George Harrison")
# AND NEITHER WILL THIS
beatles.members = [john, paul, ringo, george]

beatles.members.clear()

#ищет все группы с members, содержащей музыкантов (Person), с именем начинающимся на 'Paul'
Group.objects.filter(members__name__startswith='Paul')

# ищет всех музыкантов, которые присоединились к группе The Beatles после 1.1.1961
Person.objects.filter(
    group__name='The Beatles',
    membership__date_joined__gt=date(1961,1,1))

ringos_membership = Membership.objects.get(group=beatles, person=ringo)
ringos_membership.date_joined

ringos_membership.invite_reason

ringos_membership = ringo.membership_set.get(group=beatles)
ringos_membership.date_joined

ringos_membership.invite_reason

class Author(models.Model):
    user = models.OneToOneField(User, parent_link=True)
    introduction = models.TextField(blank=True)
    pictures = models.ManyToManyField('Graphic', related_name='users', null=True)
    organizations = models.ManyToManyField('Organization', related_name='members')
    expertise = models.ManyToManyField('Tag', related_name='experts', null=True)
    interests = models.ManyToManyField('Tag', related_name='interested_in', null=True)
    saved_articles = models.ManyToManyField(Article, related_name='favorited_by', null=True, through='SavedArticles')
    authors_followed = models.ManytoManyField('self', related_name='following_authors', null=True, through='FollowedAuthors', symmetrical=False)
 
 
class FollowedAuthors(models.Model):
    author = models.ForeignKey(Author)
    trustee = models.ForeignKey(Author)
    notes = models.TextField()
    tags = models.ManyToManyField('Tag')

MyAuthor.following_authors.all()

MyAuthor.author_followed.all()

class Relationship(models.Model):
    from_person = models.ForeignKey(User, on_delete=models.CASCADE, related_name="from_person")
    to_person = models.ForeignKey(User, on_delete=models.CASCADE, related_name="to_person")

User.objects.filter(from_person__from_person__in=request.user.friends.all(), from_person__to_person=request.user)

class Car:      
      def __init__(self, w_a):
              self.weight_auto = w_a 
              self.koleco = 4
 
class Kran(Car):
      def __init__(w_a, weight_all):
              super(Volc, self).__init__(w_a)
              self.weight_allpwed= self.weight_all

class Book(models.Model):
    title = models.CharField(max_length=100)
 
    @classmethod
    def create(cls, title):
        book = cls(title=title)
        # do something with the book
        return book
 
book = Book.create("Pride and Prejudice")

class BookManager(models.Manager):
    def create_book(self, title):
        book = self.create(title=title)
        # do something with the book
        return book
 
class Book(models.Model):
    title = models.CharField(max_length=100)
 
    objects = BookManager()
 
book = Book.objects.create_book("Pride and Prejudice")

class Dialogue(models.Model):
    Partakers = ArrayField(models.BigIntegerField(), null=False, unique=True)
    def __init__(self, partrs, *args, **kwargs):
        super(Dialogue, self).__init__(*args, **kwargs)
        self.Partakers = partrs

Dialog = Dialogue.objects.create(partrs=[int(self.request.POST['userid'])])

id = Dialogue.objects.get(id=1).id

class Message(models.Model):
 
    Dialog = models.ForeignKey(Dialogue)
    Sender = models.ForeignKey(Profile)
    Content = models.TextField()
    DateTime = models.DateTimeField()

def __init__(self, receiver, sender, content,*args,**kwargs):
          super(Message, self).__init__(*args,**kwargs)

msg = Message.objects.create(sender=request.user, content=request.POST.get('value', ''),receiver=receivers)

    def __init__(self, **kwargs): #
 
        if kwargs.has_key('receiver'): receiver = kwargs['receiver']; kwargs.pop('receiver')
 
        super(Message, self).__init__(**kwargs) #receiver, sender, content,
 
        if dir().__contains__('receiver'):
                  #далее ваш код