149 lines
5.5 KiB
Python
149 lines
5.5 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 collections import OrderedDict
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from django.apps import apps
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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.encoding import is_protected_type
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class Serializer(base.Serializer):
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"""
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Serialize 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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data = OrderedDict([('model', str(obj._meta))])
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if not self.use_natural_primary_keys or not hasattr(obj, 'natural_key'):
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data["pk"] = self._value_from_field(obj, obj._meta.pk)
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data['fields'] = self._current
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return data
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def _value_from_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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return value if is_protected_type(value) else field.value_to_string(obj)
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def handle_field(self, obj, field):
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self._current[field.name] = self._value_from_field(obj, field)
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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 = self._value_from_field(obj, field)
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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 self._value_from_field(value, value._meta.pk)
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self._current[field.name] = [
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m2m_value(related) for related in getattr(obj, field.name).iterator()
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]
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def getvalue(self):
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return self.objects
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def Deserializer(object_list, *, using=DEFAULT_DB_ALIAS, ignorenonexistent=False, **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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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 ignorenonexistent:
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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 d["fields"].items():
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if ignorenonexistent 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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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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try:
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values = base.deserialize_m2m_values(field, field_value, using)
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except base.M2MDeserializationError as e:
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raise base.DeserializationError.WithData(e.original_exc, d['model'], d.get('pk'), e.pk)
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m2m_data[field.name] = values
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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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try:
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value = base.deserialize_fk_value(field, field_value, using)
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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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data[field.attname] = value
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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, using)
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yield base.DeserializedObject(obj, m2m_data)
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def _get_model(model_identifier):
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"""Look up a model from an "app_label.model_name" string."""
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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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