287 lines
11 KiB
Python
287 lines
11 KiB
Python
"""
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XML serializer.
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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.xmlutils import SimplerXMLGenerator
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from django.utils.encoding import smart_unicode
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from xml.dom import pulldom
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class Serializer(base.Serializer):
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"""
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Serializes a QuerySet to XML.
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"""
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def indent(self, level):
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if self.options.get('indent', None) is not None:
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self.xml.ignorableWhitespace('\n' + ' ' * self.options.get('indent', None) * level)
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def start_serialization(self):
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"""
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Start serialization -- open the XML document and the root element.
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"""
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self.xml = SimplerXMLGenerator(self.stream, self.options.get("encoding", settings.DEFAULT_CHARSET))
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self.xml.startDocument()
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self.xml.startElement("django-objects", {"version" : "1.0"})
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def end_serialization(self):
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"""
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End serialization -- end the document.
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"""
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self.indent(0)
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self.xml.endElement("django-objects")
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self.xml.endDocument()
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def start_object(self, obj):
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"""
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Called as each object is handled.
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"""
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if not hasattr(obj, "_meta"):
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raise base.SerializationError("Non-model object (%s) encountered during serialization" % type(obj))
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self.indent(1)
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self.xml.startElement("object", {
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"pk" : smart_unicode(obj._get_pk_val()),
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"model" : smart_unicode(obj._meta),
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})
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def end_object(self, obj):
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"""
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Called after handling all fields for an object.
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"""
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self.indent(1)
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self.xml.endElement("object")
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def handle_field(self, obj, field):
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"""
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Called to handle each field on an object (except for ForeignKeys and
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ManyToManyFields)
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"""
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self.indent(2)
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self.xml.startElement("field", {
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"name" : field.name,
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"type" : field.get_internal_type()
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})
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# Get a "string version" of the object's data.
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if getattr(obj, field.name) is not None:
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self.xml.characters(field.value_to_string(obj))
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else:
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self.xml.addQuickElement("None")
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self.xml.endElement("field")
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def handle_fk_field(self, obj, field):
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"""
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Called to handle a ForeignKey (we need to treat them slightly
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differently from regular fields).
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"""
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self._start_relational_field(field)
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related = getattr(obj, field.name)
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if related is not None:
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if self.use_natural_keys and hasattr(related, 'natural_key'):
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# If related object has a natural key, use it
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related = related.natural_key()
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# Iterable natural keys are rolled out as subelements
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for key_value in related:
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self.xml.startElement("natural", {})
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self.xml.characters(smart_unicode(key_value))
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self.xml.endElement("natural")
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else:
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if field.rel.field_name == related._meta.pk.name:
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# Related to remote object via primary key
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related = related._get_pk_val()
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else:
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# Related to remote object via other field
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related = getattr(related, field.rel.field_name)
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self.xml.characters(smart_unicode(related))
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else:
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self.xml.addQuickElement("None")
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self.xml.endElement("field")
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def handle_m2m_field(self, obj, field):
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"""
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Called to handle a ManyToManyField. Related objects are only
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serialized as references to the object's PK (i.e. the related *data*
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is not dumped, just the relation).
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"""
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if field.rel.through._meta.auto_created:
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self._start_relational_field(field)
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if self.use_natural_keys and hasattr(field.rel.to, 'natural_key'):
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# If the objects in the m2m have a natural key, use it
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def handle_m2m(value):
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natural = value.natural_key()
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# Iterable natural keys are rolled out as subelements
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self.xml.startElement("object", {})
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for key_value in natural:
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self.xml.startElement("natural", {})
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self.xml.characters(smart_unicode(key_value))
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self.xml.endElement("natural")
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self.xml.endElement("object")
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else:
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def handle_m2m(value):
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self.xml.addQuickElement("object", attrs={
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'pk' : smart_unicode(value._get_pk_val())
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})
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for relobj in getattr(obj, field.name).iterator():
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handle_m2m(relobj)
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self.xml.endElement("field")
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def _start_relational_field(self, field):
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"""
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Helper to output the <field> element for relational fields
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"""
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self.indent(2)
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self.xml.startElement("field", {
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"name" : field.name,
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"rel" : field.rel.__class__.__name__,
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"to" : smart_unicode(field.rel.to._meta),
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})
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class Deserializer(base.Deserializer):
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"""
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Deserialize XML.
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"""
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def __init__(self, stream_or_string, **options):
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super(Deserializer, self).__init__(stream_or_string, **options)
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self.event_stream = pulldom.parse(self.stream)
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self.db = options.pop('using', DEFAULT_DB_ALIAS)
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def next(self):
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for event, node in self.event_stream:
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if event == "START_ELEMENT" and node.nodeName == "object":
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self.event_stream.expandNode(node)
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return self._handle_object(node)
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raise StopIteration
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def _handle_object(self, node):
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"""
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Convert an <object> node to a DeserializedObject.
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"""
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# Look up the model using the model loading mechanism. If this fails,
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# bail.
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Model = self._get_model_from_node(node, "model")
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# Start building a data dictionary from the object. If the node is
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# missing the pk attribute, bail.
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pk = node.getAttribute("pk")
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if not pk:
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raise base.DeserializationError("<object> node is missing the 'pk' attribute")
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data = {Model._meta.pk.attname : Model._meta.pk.to_python(pk)}
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# Also start building a dict of m2m data (this is saved as
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# {m2m_accessor_attribute : [list_of_related_objects]})
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m2m_data = {}
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# Deseralize each field.
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for field_node in node.getElementsByTagName("field"):
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# If the field is missing the name attribute, bail (are you
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# sensing a pattern here?)
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field_name = field_node.getAttribute("name")
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if not field_name:
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raise base.DeserializationError("<field> node is missing the 'name' attribute")
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# Get the field from the Model. This will raise a
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# FieldDoesNotExist if, well, the field doesn't exist, which will
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# be propagated correctly.
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field = Model._meta.get_field(field_name)
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# As is usually the case, relation fields get the special treatment.
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if field.rel and isinstance(field.rel, models.ManyToManyRel):
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m2m_data[field.name] = self._handle_m2m_field_node(field_node, field)
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elif field.rel and isinstance(field.rel, models.ManyToOneRel):
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data[field.attname] = self._handle_fk_field_node(field_node, field)
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else:
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if field_node.getElementsByTagName('None'):
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value = None
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else:
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value = field.to_python(getInnerText(field_node).strip())
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data[field.name] = value
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# Return a DeserializedObject so that the m2m data has a place to live.
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return base.DeserializedObject(Model(**data), m2m_data)
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def _handle_fk_field_node(self, node, field):
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"""
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Handle a <field> node for a ForeignKey
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"""
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# Check if there is a child node named 'None', returning None if so.
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if node.getElementsByTagName('None'):
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return None
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else:
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if hasattr(field.rel.to._default_manager, 'get_by_natural_key'):
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keys = node.getElementsByTagName('natural')
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if keys:
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# If there are 'natural' subelements, it must be a natural key
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field_value = [getInnerText(k).strip() for k in keys]
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obj = field.rel.to._default_manager.db_manager(self.db).get_by_natural_key(*field_value)
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obj_pk = getattr(obj, field.rel.field_name)
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else:
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# Otherwise, treat like a normal PK
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field_value = getInnerText(node).strip()
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obj_pk = field.rel.to._meta.get_field(field.rel.field_name).to_python(field_value)
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return obj_pk
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else:
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field_value = getInnerText(node).strip()
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return field.rel.to._meta.get_field(field.rel.field_name).to_python(field_value)
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def _handle_m2m_field_node(self, node, field):
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"""
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Handle a <field> node for a ManyToManyField.
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"""
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if hasattr(field.rel.to._default_manager, 'get_by_natural_key'):
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def m2m_convert(n):
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keys = n.getElementsByTagName('natural')
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if keys:
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# If there are 'natural' subelements, it must be a natural key
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field_value = [getInnerText(k).strip() for k in keys]
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obj_pk = field.rel.to._default_manager.db_manager(self.db).get_by_natural_key(*field_value).pk
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else:
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# Otherwise, treat like a normal PK value.
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obj_pk = field.rel.to._meta.pk.to_python(n.getAttribute('pk'))
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return obj_pk
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else:
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m2m_convert = lambda n: field.rel.to._meta.pk.to_python(n.getAttribute('pk'))
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return [m2m_convert(c) for c in node.getElementsByTagName("object")]
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def _get_model_from_node(self, node, attr):
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"""
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Helper to look up a model from a <object model=...> or a <field
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rel=... to=...> node.
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"""
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model_identifier = node.getAttribute(attr)
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if not model_identifier:
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raise base.DeserializationError(
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"<%s> node is missing the required '%s' attribute" \
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% (node.nodeName, attr))
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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(
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"<%s> node has invalid model identifier: '%s'" % \
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(node.nodeName, model_identifier))
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return Model
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def getInnerText(node):
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"""
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Get all the inner text of a DOM node (recursively).
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"""
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# inspired by http://mail.python.org/pipermail/xml-sig/2005-March/011022.html
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inner_text = []
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for child in node.childNodes:
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if child.nodeType == child.TEXT_NODE or child.nodeType == child.CDATA_SECTION_NODE:
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inner_text.append(child.data)
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elif child.nodeType == child.ELEMENT_NODE:
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inner_text.extend(getInnerText(child))
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else:
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pass
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return u"".join(inner_text)
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