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"""
A Python "serializer". Doesn't do much serializing per se -- just converts to
and from basic Python data types (lists, dicts, strings, etc.). Useful as a basis for
other serializers.
"""
from django.conf import settings
from django.core.serializers import base
from django.db import models
class Serializer(base.Serializer):
"""
Serializes a QuerySet to basic Python objects.
"""
def start_serialization(self):
self._current = None
self.objects = []
def end_serialization(self):
pass
def start_object(self, obj):
self._current = {}
def end_object(self, obj):
self.objects.append({
"model" : str(obj._meta),
"pk" : str(obj._get_pk_val()),
"fields" : self._current
})
self._current = None
def handle_field(self, obj, field):
self._current[field.name] = getattr(obj, field.name)
def handle_fk_field(self, obj, field):
related = getattr(obj, field.name)
if related is not None:
related = related._get_pk_val()
self._current[field.name] = related
def handle_m2m_field(self, obj, field):
self._current[field.name] = [related._get_pk_val() for related in getattr(obj, field.name).iterator()]
def getvalue(self):
return self.objects
def Deserializer(object_list, **options):
"""
Deserialize simple Python objects back into Django ORM instances.
It's expected that you pass the Python objects themselves (instead of a
stream or a string) to the constructor
"""
models.get_apps()
for d in object_list:
# Look up the model and starting build a dict of data for it.
Model = _get_model(d["model"])
data = {Model._meta.pk.name : d["pk"]}
m2m_data = {}
# Handle each field
for (field_name, field_value) in d["fields"].iteritems():
if isinstance(field_value, unicode):
field_value = field_value.encode(options.get("encoding", settings.DEFAULT_CHARSET))
field = Model._meta.get_field(field_name)
# Handle M2M relations (with in_bulk() for performance)
if field.rel and isinstance(field.rel, models.ManyToManyRel):
pks = []
for pk in field_value:
if isinstance(pk, unicode):
pk = pk.encode(options.get("encoding", settings.DEFAULT_CHARSET))
m2m_data[field.name] = field.rel.to._default_manager.in_bulk(field_value).values()
# Handle FK fields
elif field.rel and isinstance(field.rel, models.ManyToOneRel):
try:
data[field.name] = field.rel.to._default_manager.get(pk=field_value)
except field.rel.to.DoesNotExist:
data[field.name] = None
# Handle all other fields
else:
data[field.name] = field.to_python(field_value)
yield base.DeserializedObject(Model(**data), m2m_data)
def _get_model(model_identifier):
"""
Helper to look up a model from an "app_label.module_name" string.
"""
try:
Model = models.get_model(*model_identifier.split("."))
except TypeError:
Model = None
if Model is None:
raise base.DeserializationError("Invalid model identifier: '%s'" % model_identifier)
return Model
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