См.также
If you just want to get some data from your tables into a serialized form, you could use the dumpdata management command.
from django.core import serializers
data = serializers.serialize("xml", SomeModel.objects.all())
XMLSerializer = serializers.get_serializer("xml")
xml_serializer = XMLSerializer()
xml_serializer.serialize(queryset)
data = xml_serializer.getvalue()
out = open("file.xml", "w")
xml_serializer.serialize(SomeModel.objects.all(), stream=out)
Примечание
Calling get_serializer() with an unknown format will raise a SerializerDoesNotExist exception.
from django.core import serializers
data = serializers.serialize('xml', SomeModel.objects.all(), fields=('name','size'))
Примечание
Depending on your model, you may find that it is not possible to deserialize a model that only serializes a subset of its fields. If a serialized object doesn’t specify all the fields that are required by a model, the deserializer will not be able to save deserialized instances.
class Place(models.Model):
name = models.CharField(max_length=50)
class Restaurant(Place):
serves_hot_dogs = models.BooleanField()
data = serializers.serialize('xml', Restaurant.objects.all())
all_objects = list(Restaurant.objects.all()) + list(Place.objects.all())
data = serializers.serialize('xml', all_objects)
for obj in serializers.deserialize("xml", data):
do_something_with(obj)
for deserialized_object in serializers.deserialize("xml", data):
if object_should_be_saved(deserialized_object):
deserialized_object.save()
| Identifier | Information |
|---|---|
| xml | Serializes to and from a simple XML dialect. |
| json | Serializes to and from JSON (using a version of simplejson bundled with Django). |
| yaml | Serializes to YAML (YAML Ain’t a Markup Language). This serializer is only available if PyYAML is installed. |
json_serializer = serializers.get_serializer("json")()
json_serializer.serialize(queryset, ensure_ascii=False, stream=response)
from django.utils.functional import Promise
from django.utils.encoding import force_unicode
class LazyEncoder(simplejson.JSONEncoder):
def default(self, obj):
if isinstance(obj, Promise):
return force_unicode(obj)
return super(LazyEncoder, self).default(obj)
Предупреждение
You should never include automatically generated objects in a fixture or other serialized data. By chance, the primary keys in the fixture may match those in the database and loading the fixture will have no effect. In the more likely case that they don’t match, the fixture loading will fail with an IntegrityError.
from django.db import models
class Person(models.Model):
first_name = models.CharField(max_length=100)
last_name = models.CharField(max_length=100)
birthdate = models.DateField()
class Meta:
unique_together = (('first_name', 'last_name'),)
class Book(models.Model):
name = models.CharField(max_length=100)
author = models.ForeignKey(Person)
...
{
"pk": 1,
"model": "store.book",
"fields": {
"name": "Mostly Harmless",
"author": 42
}
}
...
from django.db import models
class PersonManager(models.Manager):
def get_by_natural_key(self, first_name, last_name):
return self.get(first_name=first_name, last_name=last_name)
class Person(models.Model):
objects = PersonManager()
first_name = models.CharField(max_length=100)
last_name = models.CharField(max_length=100)
birthdate = models.DateField()
class Meta:
unique_together = (('first_name', 'last_name'),)
...
{
"pk": 1,
"model": "store.book",
"fields": {
"name": "Mostly Harmless",
"author": ["Douglas", "Adams"]
}
}
...
Примечание
Whatever fields you use for a natural key must be able to uniquely identify an object. This will usually mean that your model will have a uniqueness clause (either unique=True on a single field, or unique_together over multiple fields) for the field or fields in your natural key. However, uniqueness doesn’t need to be enforced at the database level. If you are certain that a set of fields will be effectively unique, you can still use those fields as a natural key.
class Person(models.Model):
objects = PersonManager()
first_name = models.CharField(max_length=100)
last_name = models.CharField(max_length=100)
birthdate = models.DateField()
def natural_key(self):
return (self.first_name, self.last_name)
class Meta:
unique_together = (('first_name', 'last_name'),)
>>> serializers.serialize('json', [book1, book2], indent=2, use_natural_keys=True)
Примечание
You don’t need to define both natural_key() and get_by_natural_key(). If you don’t want Django to output natural keys during serialization, but you want to retain the ability to load natural keys, then you can opt to not implement the natural_key() method.
Conversely, if (for some strange reason) you want Django to output natural keys during serialization, but not be able to load those key values, just don’t define the get_by_natural_key() method.
class Book(models.Model):
name = models.CharField(max_length=100)
author = models.ForeignKey(Person)
def natural_key(self):
return (self.name,) + self.author.natural_key()
def natural_key(self):
return (self.name,) + self.author.natural_key()
natural_key.dependencies = ['example_app.person']
Aug 21, 2013