Add serializer handling natural keys (refs #5510)

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Benjamin Dauvergne 2014-09-29 15:03:09 +02:00
parent 6ee88e9fb9
commit a58b57d465
1 changed files with 156 additions and 0 deletions

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import json
import sys
from django.utils import six
from django.core.serializers.json import Serializer as JSONSerializer
from django.core.serializers.python import _get_model
from django.core.serializers import base
from django.core.serializers.base import DeserializationError
from django.contrib.contenttypes.generic import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.db.models import FieldDoesNotExist
from django.utils.encoding import smart_text
from django.conf import settings
from django.db import models, DEFAULT_DB_ALIAS
def PythonDeserializer(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)
ignore = options.pop('ignorenonexistent', False)
for d in object_list:
# Look up the model and starting build a dict of data for it.
Model = _get_model(d["model"])
data = {}
if 'pk' in d:
data[Model._meta.pk.attname] = Model._meta.pk.to_python(d.get("pk", None))
m2m_data = {}
model_fields = Model._meta.get_all_field_names()
# Handle each field
for (field_name, field_value) in six.iteritems(d["fields"]):
if ignore and field_name not in model_fields:
# skip fields no longer on model
continue
if isinstance(field_value, str):
field_value = smart_text(field_value, options.get("encoding", settings.DEFAULT_CHARSET), strings_only=True)
try:
field = Model._meta.get_field(field_name)
except FieldDoesNotExist:
for field in Model._meta.virtual_fields:
if field.name == field_name:
break
else:
raise
# Handle M2M relations
if hasattr(field, 'rel'):
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__') and not isinstance(value, six.text_type):
try:
return field.rel.to._default_manager.db_manager(db).get_by_natural_key(*value).pk
except Exception:
import pdb
pdb.set_trace()
else:
return smart_text(field.rel.to._meta.pk.to_python(value))
else:
m2m_convert = lambda v: smart_text(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__') and not isinstance(field_value, six.text_type):
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
else:
data[field.name] = field.to_python(field_value)
# Handle Generic foreign key
elif isinstance(field, GenericForeignKey):
ct_natural_key, fk_natural_key = field_value
ct = ContentType.objects.get_by_natural_key(*ct_natural_key)
data[field.name] = ct.model_class().objects.get_by_natural_key(*fk_natural_key)
# Handle all other fields
else:
raise NotImplementedError('unsupported field type %s' % field)
yield base.DeserializedObject(Model(**data), m2m_data)
class Serializer(JSONSerializer):
def get_dump_object(self, obj):
d = super(Serializer, self).get_dump_object(obj)
if self.use_natural_keys:
if hasattr(obj, 'natural_key'):
d['pk'] = obj.natural_key()
for vfield in obj.__class__._meta.virtual_fields:
if not isinstance(vfield, GenericForeignKey):
continue
ct = getattr(obj, vfield.ct_field)
if ct is None:
continue
sub_obj = getattr(obj, vfield.name)
assert not sub_obj is None, 'should not happen'
if not hasattr(sub_obj, 'natural_key'):
# abort if no natural key
continue
# delete non natural keys
fields = d['fields']
del fields[vfield.ct_field]
del fields[vfield.fk_field]
fields[vfield.name] = (ct.natural_key(), sub_obj.natural_key())
return d
def Deserializer(stream_or_string, **options):
"""
Deserialize a stream or string of JSON data.
"""
if not isinstance(stream_or_string, (bytes, six.string_types)):
stream_or_string = stream_or_string.read()
if isinstance(stream_or_string, bytes):
stream_or_string = stream_or_string.decode('utf-8')
try:
objects = json.loads(stream_or_string)
for obj in objects:
Model = _get_model(obj['model'])
if isinstance(obj['pk'], (tuple, list)):
try:
o = Model.objects.get_by_natural_key(*obj['pk'])
except Model.DoesNotExist:
obj['pk'] = None
else:
obj['pk'] = o.pk
for obj in PythonDeserializer(objects, **options):
yield obj
except GeneratorExit:
raise
except Exception as e:
# Map to deserializer error
six.reraise(DeserializationError, DeserializationError(e), sys.exc_info()[2])