195 lines
7.7 KiB
Python
195 lines
7.7 KiB
Python
"""
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A Python "serializer". Doesn't do much serializing per se -- just converts to
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and from basic Python data types (lists, dicts, strings, etc.). Useful as a basis for
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other serializers.
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"""
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from __future__ import unicode_literals
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from collections import OrderedDict
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from django.apps import apps
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from django.conf import settings
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from django.core.serializers import base
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from django.db import DEFAULT_DB_ALIAS, models
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from django.utils import six
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from django.utils.encoding import force_text, is_protected_type
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class Serializer(base.Serializer):
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"""
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Serializes a QuerySet to basic Python objects.
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"""
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internal_use_only = True
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def start_serialization(self):
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self._current = None
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self.objects = []
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def end_serialization(self):
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pass
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def start_object(self, obj):
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self._current = OrderedDict()
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def end_object(self, obj):
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self.objects.append(self.get_dump_object(obj))
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self._current = None
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def get_dump_object(self, obj):
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model = obj._meta.proxy_for_model if obj._deferred else obj.__class__
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data = OrderedDict([('model', force_text(model._meta))])
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if not self.use_natural_primary_keys or not hasattr(obj, 'natural_key'):
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data["pk"] = force_text(obj._get_pk_val(), strings_only=True)
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data['fields'] = self._current
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return data
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def handle_field(self, obj, field):
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value = field.value_from_object(obj)
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# Protected types (i.e., primitives like None, numbers, dates,
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# and Decimals) are passed through as is. All other values are
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# converted to string first.
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if is_protected_type(value):
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self._current[field.name] = value
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else:
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self._current[field.name] = field.value_to_string(obj)
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def handle_fk_field(self, obj, field):
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if self.use_natural_foreign_keys and hasattr(field.remote_field.model, 'natural_key'):
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related = getattr(obj, field.name)
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if related:
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value = related.natural_key()
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else:
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value = None
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else:
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value = getattr(obj, field.get_attname())
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if not is_protected_type(value):
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value = field.value_to_string(obj)
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self._current[field.name] = value
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def handle_m2m_field(self, obj, field):
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if field.remote_field.through._meta.auto_created:
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if self.use_natural_foreign_keys and hasattr(field.remote_field.model, 'natural_key'):
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def m2m_value(value):
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return value.natural_key()
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else:
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def m2m_value(value):
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return force_text(value._get_pk_val(), strings_only=True)
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self._current[field.name] = [m2m_value(related)
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for related in getattr(obj, field.name).iterator()]
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def getvalue(self):
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return self.objects
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def Deserializer(object_list, **options):
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"""
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Deserialize simple Python objects back into Django ORM instances.
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It's expected that you pass the Python objects themselves (instead of a
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stream or a string) to the constructor
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"""
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db = options.pop('using', DEFAULT_DB_ALIAS)
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ignore = options.pop('ignorenonexistent', False)
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field_names_cache = {} # Model: <list of field_names>
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for d in object_list:
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# Look up the model and starting build a dict of data for it.
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try:
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Model = _get_model(d["model"])
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except base.DeserializationError:
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if ignore:
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continue
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else:
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raise
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data = {}
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if 'pk' in d:
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try:
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data[Model._meta.pk.attname] = Model._meta.pk.to_python(d.get('pk'))
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except Exception as e:
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raise base.DeserializationError.WithData(e, d['model'], d.get('pk'), None)
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m2m_data = {}
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if Model not in field_names_cache:
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field_names_cache[Model] = {f.name for f in Model._meta.get_fields()}
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field_names = field_names_cache[Model]
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# Handle each field
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for (field_name, field_value) in six.iteritems(d["fields"]):
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if ignore and field_name not in field_names:
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# skip fields no longer on model
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continue
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if isinstance(field_value, str):
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field_value = force_text(
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field_value, options.get("encoding", settings.DEFAULT_CHARSET), strings_only=True
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)
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field = Model._meta.get_field(field_name)
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# Handle M2M relations
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if field.remote_field and isinstance(field.remote_field, models.ManyToManyRel):
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model = field.remote_field.model
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if hasattr(model._default_manager, 'get_by_natural_key'):
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def m2m_convert(value):
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if hasattr(value, '__iter__') and not isinstance(value, six.text_type):
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return model._default_manager.db_manager(db).get_by_natural_key(*value).pk
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else:
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return force_text(model._meta.pk.to_python(value), strings_only=True)
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else:
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def m2m_convert(v):
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return force_text(model._meta.pk.to_python(v), strings_only=True)
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try:
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m2m_data[field.name] = []
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for pk in field_value:
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m2m_data[field.name].append(m2m_convert(pk))
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except Exception as e:
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raise base.DeserializationError.WithData(e, d['model'], d.get('pk'), pk)
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# Handle FK fields
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elif field.remote_field and isinstance(field.remote_field, models.ManyToOneRel):
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model = field.remote_field.model
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if field_value is not None:
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try:
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default_manager = model._default_manager
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field_name = field.remote_field.field_name
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if hasattr(default_manager, 'get_by_natural_key'):
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if hasattr(field_value, '__iter__') and not isinstance(field_value, six.text_type):
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obj = default_manager.db_manager(db).get_by_natural_key(*field_value)
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value = getattr(obj, field.remote_field.field_name)
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# If this is a natural foreign key to an object that
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# has a FK/O2O as the foreign key, use the FK value
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if model._meta.pk.remote_field:
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value = value.pk
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else:
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value = model._meta.get_field(field_name).to_python(field_value)
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data[field.attname] = value
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else:
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data[field.attname] = model._meta.get_field(field_name).to_python(field_value)
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except Exception as e:
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raise base.DeserializationError.WithData(e, d['model'], d.get('pk'), field_value)
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else:
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data[field.attname] = None
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# Handle all other fields
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else:
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try:
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data[field.name] = field.to_python(field_value)
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except Exception as e:
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raise base.DeserializationError.WithData(e, d['model'], d.get('pk'), field_value)
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obj = base.build_instance(Model, data, db)
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yield base.DeserializedObject(obj, m2m_data)
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def _get_model(model_identifier):
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"""
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Helper to look up a model from an "app_label.model_name" string.
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"""
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try:
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return apps.get_model(model_identifier)
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except (LookupError, TypeError):
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raise base.DeserializationError("Invalid model identifier: '%s'" % model_identifier)
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