Django ORM cookbook
Django ORM cookbook is a set of recipes of how to do things with Django.
They take the form of about 50 questions of the form
How to do X with Django ORM/Queryset.
We have a set of models which we use across the book for answering these questions.
The models
You plan to write a set of models and an assoicated admin for UMSRA researchers. You come up with two apps entities and events. The models are
Events
from django.db import models
from django.utils.text import slugify
from entities.models import Hero, Villain
from django.contrib.auth.models import User
import uuid
class Epic(models.Model):
name = models.CharField(max_length=255)
participating_heroes = models.ManyToManyField(Hero)
participating_villains = models.ManyToManyField(Villain)
class Event(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
epic = models.ForeignKey(Epic, on_delete=models.CASCADE)
details = models.TextField()
years_ago = models.PositiveIntegerField()
class EventHero(models.Model):
event = models.ForeignKey(Event, on_delete=models.CASCADE)
hero = models.ForeignKey(Hero, on_delete=models.CASCADE)
is_primary = models.BooleanField()
class EventVillain(models.Model):
event = models.ForeignKey(Event, on_delete=models.CASCADE)
hero = models.ForeignKey(Villain, on_delete=models.CASCADE)
is_primary = models.BooleanField()
class UserParent(models.Model):
user = models.OneToOneField(
User,
on_delete=models.CASCADE,
primary_key=True,
)
father_name = models.CharField(max_length=100)
mother_name = models.CharField(max_length=100)
class Article(models.Model):
headline = models.CharField(max_length=100)
pub_date = models.DateField()
reporter = models.ForeignKey(User, on_delete=models.CASCADE, related_name='reporter')
slug = models.SlugField()
def save(self, *args, **kwargs):
self.slug = slugify(self.headline)
super(Article, self).save(*args, **kwargs)
def __str__(self):
return self.headline
class Meta:
ordering = ('headline',)
class TempUser(models.Model):
first_name = models.CharField(max_length=100)
class Meta:
managed = False
db_table = "temp_user"
class ColumnName(models.Model):
a = models.CharField(max_length=40,db_column='column1')
column2 = models.CharField(max_length=50)
def __str__(self):
return self.a
Entities
from django.db import models
from django.conf import settings
class Category(models.Model):
name = models.CharField(max_length=100)
class Meta:
verbose_name_plural = "Categories"
def __str__(self):
return self.name
class Origin(models.Model):
name = models.CharField(max_length=100)
def __str__(self):
return self.name
class Entity(models.Model):
GENDER_MALE = "Male"
GENDER_FEMALE = "Female"
GENDER_OTHERS = "Others/Unknown"
name = models.CharField(max_length=100)
alternative_name = models.CharField(
max_length=100, null=True, blank=True
)
category = models.ForeignKey(Category, on_delete=models.CASCADE)
origin = models.ForeignKey(Origin, on_delete=models.CASCADE)
gender = models.CharField(
max_length=100,
choices=(
(GENDER_MALE, GENDER_MALE),
(GENDER_FEMALE, GENDER_FEMALE),
(GENDER_OTHERS, GENDER_OTHERS),
)
)
description = models.TextField()
added_by = models.ForeignKey(settings.AUTH_USER_MODEL,
null=True, blank=True, on_delete=models.SET_NULL)
added_on = models.DateField(auto_now=True)
def __str__(self):
return self.name
class Meta:
abstract = True
class Hero(Entity):
class Meta:
verbose_name_plural = "Heroes"
is_immortal = models.BooleanField(default=True)
benevolence_factor = models.PositiveSmallIntegerField(
help_text="How benevolent this hero is?"
)
arbitrariness_factor = models.PositiveSmallIntegerField(
help_text="How arbitrary this hero is?"
)
headshot = models.ImageField(null=True, blank=True, upload_to="hero_headshots/")
# relationships
father = models.ForeignKey(
"self", related_name="children", null=True, blank=True, on_delete=models.SET_NULL
)
mother = models.ForeignKey(
"self", related_name="+", null=True, blank=True, on_delete=models.SET_NULL
)
spouse = models.ForeignKey(
"self", related_name="+", null=True, blank=True, on_delete=models.SET_NULL
)
class HeroProxy(Hero):
class Meta:
proxy = True
class Villain(Entity):
is_immortal = models.BooleanField(default=False)
malevolence_factor = models.PositiveSmallIntegerField(
help_text="How malevolent this villain is?"
)
power_factor = models.PositiveSmallIntegerField(
help_text="How powerful this villain is?"
)
is_unique = models.BooleanField(default=True)
count = models.PositiveSmallIntegerField(default=1)
class HeroAcquaintance(models.Model):
"Non family contacts of a Hero"
hero = models.OneToOneField(Hero, on_delete=models.CASCADE)
friends = models.ManyToManyField(Hero, related_name="+")
detractors = models.ManyToManyField(Hero, related_name="+")
main_anatagonists = models.ManyToManyField(Villain, related_name="+")
class AllEntity(models.Model):
name = models.CharField(max_length=100)
class Meta:
managed = False
db_table = "entities_entity"