def _get_model_from_node(self, node, attr):
"""
Helper to look up a model from a <object model=...> or a <field
rel=... to=...> node.
"""
model_identifier = node.getAttribute(attr)
if not model_identifier:
raise base.DeserializationError(
"<%s> node is missing the required '%s' attribute" %
(node.nodeName, attr))
try:
Model = models.get_model(*model_identifier.split("."))
except TypeError:
Model = None
if Model is None:
raise base.DeserializationError(
"<%s> node has invalid model identifier: '%s'" %
(node.nodeName, model_identifier))
return Model
def _get_model(model_identifier):
"""
Helper to look up a model from an "app_label.module_name" string.
"""
try:
Model = models.get_model(*model_identifier.split("."))
except TypeError:
Model = None
if Model is None:
raise base.DeserializationError("Invalid model identifier: '%s'" %
model_identifier)
return Model
def _handle_object(self, node):
"""
Convert an <object> node to a DeserializedObject.
"""
# Look up the model using the model loading mechanism. If this fails,
# bail.
Model = self._get_model_from_node(node, "model")
# Start building a data dictionary from the object.
# If the node is missing the pk set it to None
if node.hasAttribute("pk"):
pk = node.getAttribute("pk")
else:
pk = None
data = {Model._meta.pk.attname: Model._meta.pk.to_python(pk)}
# Also start building a dict of m2m data (this is saved as
# {m2m_accessor_attribute : [list_of_related_objects]})
m2m_data = {}
# Deseralize each field.
for field_node in node.getElementsByTagName("field"):
# If the field is missing the name attribute, bail (are you
# sensing a pattern here?)
field_name = field_node.getAttribute("name")
if not field_name:
raise base.DeserializationError(
"<field> node is missing the 'name' attribute")
# Get the field from the Model. This will raise a
# FieldDoesNotExist if, well, the field doesn't exist, which will
# be propagated correctly.
field = Model._meta.get_field(field_name)
# As is usually the case, relation fields get the special treatment.
if field.rel and isinstance(field.rel, models.ManyToManyRel):
m2m_data[field.name] = self._handle_m2m_field_node(
field_node, field)
elif field.rel and isinstance(field.rel, models.ManyToOneRel):
data[field.attname] = self._handle_fk_field_node(
field_node, field)
else:
if field_node.getElementsByTagName('None'):
value = None
else:
value = field.to_python(getInnerText(field_node).strip())
data[field.name] = value
# Return a DeserializedObject so that the m2m data has a place to live.
return base.DeserializedObject(Model(**data), m2m_data)