102 lines
3.5 KiB
Python
102 lines
3.5 KiB
Python
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"""
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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
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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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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" : str(obj._meta),
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"pk" : str(obj._get_pk_val()),
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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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self._current[field.name] = getattr(obj, field.name)
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def handle_fk_field(self, obj, field):
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related = getattr(obj, field.name)
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if related is not None:
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related = related._get_pk_val()
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self._current[field.name] = related
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def handle_m2m_field(self, obj, field):
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self._current[field.name] = [related._get_pk_val() 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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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.name : 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, unicode):
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field_value = field_value.encode(options.get("encoding", settings.DEFAULT_CHARSET))
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field = Model._meta.get_field(field_name)
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# Handle M2M relations (with in_bulk() for performance)
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if field.rel and isinstance(field.rel, models.ManyToManyRel):
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pks = []
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for pk in field_value:
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if isinstance(pk, unicode):
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pk = pk.encode(options.get("encoding", settings.DEFAULT_CHARSET))
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m2m_data[field.name] = field.rel.to._default_manager.in_bulk(field_value).values()
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# Handle FK fields
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elif field.rel and isinstance(field.rel, models.ManyToOneRel):
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try:
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data[field.name] = field.rel.to._default_manager.get(pk=field_value)
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except RelatedModel.DoesNotExist:
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data[field.name] = 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("Invalid model identifier: '%s'" % model_identifier)
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return Model
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