140 lines
5.5 KiB
Python
140 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 django.conf import settings
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from django.core.serializers import base
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from django.db import models, DEFAULT_DB_ALIAS
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from django.utils.encoding import smart_unicode, 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 = {}
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def end_object(self, obj):
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self.objects.append({
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"model" : smart_unicode(obj._meta),
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"pk" : smart_unicode(obj._get_pk_val(), strings_only=True),
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"fields" : self._current
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})
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self._current = None
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def handle_field(self, obj, field):
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value = field._get_val_from_obj(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_keys and hasattr(field.rel.to, '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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self._current[field.name] = value
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def handle_m2m_field(self, obj, field):
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if field.rel.through._meta.auto_created:
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if self.use_natural_keys and hasattr(field.rel.to, 'natural_key'):
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m2m_value = lambda value: value.natural_key()
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else:
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m2m_value = lambda value: smart_unicode(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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models.get_apps()
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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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Model = _get_model(d["model"])
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data = {Model._meta.pk.attname : Model._meta.pk.to_python(d["pk"])}
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m2m_data = {}
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# Handle each field
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for (field_name, field_value) in d["fields"].iteritems():
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if isinstance(field_value, str):
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field_value = smart_unicode(field_value, options.get("encoding", settings.DEFAULT_CHARSET), strings_only=True)
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field = Model._meta.get_field(field_name)
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# Handle M2M relations
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if field.rel and isinstance(field.rel, models.ManyToManyRel):
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if hasattr(field.rel.to._default_manager, 'get_by_natural_key'):
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def m2m_convert(value):
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if hasattr(value, '__iter__'):
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return field.rel.to._default_manager.db_manager(db).get_by_natural_key(*value).pk
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else:
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return smart_unicode(field.rel.to._meta.pk.to_python(value))
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else:
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m2m_convert = lambda v: smart_unicode(field.rel.to._meta.pk.to_python(v))
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m2m_data[field.name] = [m2m_convert(pk) for pk in field_value]
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# Handle FK fields
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elif field.rel and isinstance(field.rel, models.ManyToOneRel):
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if field_value is not None:
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if hasattr(field.rel.to._default_manager, 'get_by_natural_key'):
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if hasattr(field_value, '__iter__'):
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obj = field.rel.to._default_manager.db_manager(db).get_by_natural_key(*field_value)
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value = getattr(obj, field.rel.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 field.rel.to._meta.pk.rel:
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value = value.pk
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else:
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value = field.rel.to._meta.get_field(field.rel.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] = field.rel.to._meta.get_field(field.rel.field_name).to_python(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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data[field.name] = field.to_python(field_value)
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yield base.DeserializedObject(Model(**data), 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.module_name" string.
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"""
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try:
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Model = models.get_model(*model_identifier.split("."))
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except TypeError:
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Model = None
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if Model is None:
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raise base.DeserializationError(u"Invalid model identifier: '%s'" % model_identifier)
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return Model
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