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"""
Serialization
``django.core.serializers`` provides interfaces to converting Django
``QuerySet`` objects to and from "flat" data (i.e. strings).
"""
from decimal import Decimal
from django.db import models
class CategoryMetaDataManager(models.Manager):
def get_by_natural_key(self, kind, name):
return self.get(kind=kind, name=name)
class CategoryMetaData(models.Model):
kind = models.CharField(max_length=10)
name = models.CharField(max_length=10)
value = models.CharField(max_length=10)
objects = CategoryMetaDataManager()
class Meta:
unique_together = (("kind", "name"),)
def __str__(self):
return "[%s:%s]=%s" % (self.kind, self.name, self.value)
def natural_key(self):
return (self.kind, self.name)
class Category(models.Model):
name = models.CharField(max_length=20)
meta_data = models.ForeignKey(
CategoryMetaData, models.SET_NULL, null=True, default=None
)
class Meta:
ordering = ("name",)
def __str__(self):
return self.name
class Author(models.Model):
name = models.CharField(max_length=20)
class Meta:
ordering = ("name",)
def __str__(self):
return self.name
class Article(models.Model):
author = models.ForeignKey(Author, models.CASCADE)
headline = models.CharField(max_length=50)
pub_date = models.DateTimeField()
categories = models.ManyToManyField(Category)
meta_data = models.ManyToManyField(CategoryMetaData)
class Meta:
ordering = ("pub_date",)
def __str__(self):
return self.headline
class AuthorProfile(models.Model):
author = models.OneToOneField(Author, models.CASCADE, primary_key=True)
date_of_birth = models.DateField()
def __str__(self):
return "Profile of %s" % self.author
class Actor(models.Model):
name = models.CharField(max_length=20, primary_key=True)
class Meta:
ordering = ("name",)
def __str__(self):
return self.name
class Movie(models.Model):
actor = models.ForeignKey(Actor, models.CASCADE)
title = models.CharField(max_length=50)
price = models.DecimalField(max_digits=6, decimal_places=2, default=Decimal("0.00"))
class Meta:
ordering = ("title",)
def __str__(self):
return self.title
class Score(models.Model):
score = models.FloatField()
class Team:
def __init__(self, title):
self.title = title
def __str__(self):
raise NotImplementedError("Not so simple")
def to_string(self):
return str(self.title)
class TeamField(models.CharField):
def __init__(self):
super().__init__(max_length=100)
def get_db_prep_save(self, value, connection):
return str(value.title)
def to_python(self, value):
if isinstance(value, Team):
return value
return Team(value)
def from_db_value(self, value, expression, connection):
return Team(value)
def value_to_string(self, obj):
return self.value_from_object(obj).to_string()
def deconstruct(self):
name, path, args, kwargs = super().deconstruct()
del kwargs["max_length"]
return name, path, args, kwargs
class Player(models.Model):
name = models.CharField(max_length=50)
rank = models.IntegerField()
team = TeamField()
def __str__(self):
return "%s (%d) playing for %s" % (self.name, self.rank, self.team.to_string())
class BaseModel(models.Model):
parent_data = models.IntegerField()
class ProxyBaseModel(BaseModel):
class Meta:
proxy = True
class ProxyProxyBaseModel(ProxyBaseModel):
class Meta:
proxy = True
class ComplexModel(models.Model):
field1 = models.CharField(max_length=10)
field2 = models.CharField(max_length=10)
field3 = models.CharField(max_length=10)
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