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from django.contrib.auth.models import User
from django.db import models
from django.db.models import Case, Value, When
class PostQuerySet(models.QuerySet):
def annotate_is_published(self):
return self.annotate(is_published=Case(
When(publish_date__isnull=False, then=Value(True)),
default=Value(False),
output_field=models.BooleanField(),
))
class Note(models.Model):
title = models.CharField(max_length=100)
content = models.TextField()
author = models.ForeignKey(User, on_delete=models.CASCADE)
class Tag(models.Model):
name = models.CharField(max_length=100)
class Blog(models.Model):
name = models.CharField(max_length=100)
class Post(models.Model):
title = models.CharField(max_length=100)
content = models.TextField()
publish_date = models.DateField(null=True)
blog = models.ForeignKey(Blog, null=True, on_delete=models.CASCADE)
author = models.ForeignKey(User, null=True, on_delete=models.CASCADE)
note = models.ForeignKey(Note, null=True, on_delete=models.CASCADE)
tags = models.ManyToManyField(Tag)
objects = PostQuerySet.as_manager()
class Cover(models.Model):
comment = models.CharField(max_length=100)
post = models.ForeignKey(Post, on_delete=models.CASCADE)
class Page(models.Model):
title = models.CharField(max_length=100)
content = models.TextField()
previous_page = models.ForeignKey('self', null=True, on_delete=models.CASCADE)
class A(models.Model):
title = models.CharField(max_length=100)
b = models.ForeignKey('B', null=True, on_delete=models.CASCADE)
class B(models.Model):
name = models.CharField(max_length=100)
c = models.ForeignKey('C', null=True, on_delete=models.CASCADE)
class C(models.Model):
title = models.CharField(max_length=100)
a = models.ForeignKey('A', null=True, on_delete=models.CASCADE)
class Person(models.Model):
name = models.CharField(max_length=100)
best_friend = models.ForeignKey('self', null=True, on_delete=models.CASCADE)
date_joined = models.DateField(auto_now_add=True)
time_joined = models.TimeField(auto_now_add=True)
datetime_joined = models.DateTimeField(auto_now_add=True)
# Models using `to_field`
class Customer(models.Model):
name = models.CharField(max_length=80)
ssn = models.CharField(max_length=9, unique=True)
dob = models.DateField()
class Account(models.Model):
TYPE_CHOICES = [
('c', 'Checking'),
('s', 'Savings'),
]
customer = models.ForeignKey(Customer, to_field='ssn', on_delete=models.CASCADE)
type = models.CharField(max_length=1, choices=TYPE_CHOICES)
name = models.CharField(max_length=80)
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