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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, DEFAULT_DB_ALIAS
from django.utils.encoding import smart_unicode, is_protected_type
class Serializer(base.Serializer):
"""
Serializes a QuerySet to basic Python objects.
"""
internal_use_only = True
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" : smart_unicode(obj._meta),
"pk" : smart_unicode(obj._get_pk_val(), strings_only=True),
"fields" : self._current
})
self._current = None
def handle_field(self, obj, field):
value = field._get_val_from_obj(obj)
# Protected types (i.e., primitives like None, numbers, dates,
# and Decimals) are passed through as is. All other values are
# converted to string first.
if is_protected_type(value):
self._current[field.name] = value
else:
self._current[field.name] = field.value_to_string(obj)
def handle_fk_field(self, obj, field):
related = getattr(obj, field.name)
if related is not None:
if self.use_natural_keys and hasattr(related, 'natural_key'):
related = related.natural_key()
else:
if field.rel.field_name == related._meta.pk.name:
# Related to remote object via primary key
related = related._get_pk_val()
else:
# Related to remote object via other field
related = smart_unicode(getattr(related, field.rel.field_name), strings_only=True)
self._current[field.name] = related
def handle_m2m_field(self, obj, field):
if field.rel.through._meta.auto_created:
if self.use_natural_keys and hasattr(field.rel.to, 'natural_key'):
m2m_value = lambda value: value.natural_key()
else:
m2m_value = lambda value: smart_unicode(value._get_pk_val(), strings_only=True)
self._current[field.name] = [m2m_value(related)
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
"""
db = options.pop('using', DEFAULT_DB_ALIAS)
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.attname : Model._meta.pk.to_python(d["pk"])}
m2m_data = {}
# Handle each field
for (field_name, field_value) in d["fields"].iteritems():
if isinstance(field_value, str):
field_value = smart_unicode(field_value, options.get("encoding", settings.DEFAULT_CHARSET), strings_only=True)
field = Model._meta.get_field(field_name)
# Handle M2M relations
if field.rel and isinstance(field.rel, models.ManyToManyRel):
if hasattr(field.rel.to._default_manager, 'get_by_natural_key'):
def m2m_convert(value):
if hasattr(value, '__iter__'):
return field.rel.to._default_manager.db_manager(db).get_by_natural_key(*value).pk
else:
return smart_unicode(field.rel.to._meta.pk.to_python(value))
else:
m2m_convert = lambda v: smart_unicode(field.rel.to._meta.pk.to_python(v))
m2m_data[field.name] = [m2m_convert(pk) for pk in field_value]
# Handle FK fields
elif field.rel and isinstance(field.rel, models.ManyToOneRel):
if field_value is not None:
if hasattr(field.rel.to._default_manager, 'get_by_natural_key'):
if hasattr(field_value, '__iter__'):
obj = field.rel.to._default_manager.db_manager(db).get_by_natural_key(*field_value)
value = getattr(obj, field.rel.field_name)
# If this is a natural foreign key to an object that
# has a FK/O2O as the foreign key, use the FK value
if field.rel.to._meta.pk.rel:
value = value.pk
else:
value = field.rel.to._meta.get_field(field.rel.field_name).to_python(field_value)
data[field.attname] = value
else:
data[field.attname] = field.rel.to._meta.get_field(field.rel.field_name).to_python(field_value)
else:
data[field.attname] = 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(u"Invalid model identifier: '%s'" % model_identifier)
return Model
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