Url and Page classes used to encapsulate the "site map" information (URL
regular expressions, Django views, menu item names, etc.) and the relation
between pages in the site map.
There are still lots of TODOs in this first pass.
Patch by: Todd Larsen
Review by: to-be-reviewed
"""
XML serializer.
"""
from django.conf import settings
from django.core.serializers import base
from django.db import models
from django.utils.xmlutils import SimplerXMLGenerator
from django.utils.encoding import smart_unicode
from xml.dom import pulldom
class Serializer(base.Serializer):
"""
Serializes a QuerySet to XML.
"""
def indent(self, level):
if self.options.get('indent', None) is not None:
self.xml.ignorableWhitespace('\n' + ' ' * self.options.get('indent', None) * level)
def start_serialization(self):
"""
Start serialization -- open the XML document and the root element.
"""
self.xml = SimplerXMLGenerator(self.stream, self.options.get("encoding", settings.DEFAULT_CHARSET))
self.xml.startDocument()
self.xml.startElement("django-objects", {"version" : "1.0"})
def end_serialization(self):
"""
End serialization -- end the document.
"""
self.indent(0)
self.xml.endElement("django-objects")
self.xml.endDocument()
def start_object(self, obj):
"""
Called as each object is handled.
"""
if not hasattr(obj, "_meta"):
raise base.SerializationError("Non-model object (%s) encountered during serialization" % type(obj))
self.indent(1)
self.xml.startElement("object", {
"pk" : smart_unicode(obj._get_pk_val()),
"model" : smart_unicode(obj._meta),
})
def end_object(self, obj):
"""
Called after handling all fields for an object.
"""
self.indent(1)
self.xml.endElement("object")
def handle_field(self, obj, field):
"""
Called to handle each field on an object (except for ForeignKeys and
ManyToManyFields)
"""
self.indent(2)
self.xml.startElement("field", {
"name" : field.name,
"type" : field.get_internal_type()
})
# Get a "string version" of the object's data (this is handled by the
# serializer base class).
if getattr(obj, field.name) is not None:
value = self.get_string_value(obj, field)
self.xml.characters(smart_unicode(value))
else:
self.xml.addQuickElement("None")
self.xml.endElement("field")
def handle_fk_field(self, obj, field):
"""
Called to handle a ForeignKey (we need to treat them slightly
differently from regular fields).
"""
self._start_relational_field(field)
related = getattr(obj, field.name)
if related is not None:
if field.rel.field_name == related._meta.pk.name:
# Related to remote object via primary key
related = related._get_pk_val()
else:
# Related to remote object via other field
related = getattr(related, field.rel.field_name)
self.xml.characters(smart_unicode(related))
else:
self.xml.addQuickElement("None")
self.xml.endElement("field")
def handle_m2m_field(self, obj, field):
"""
Called to handle a ManyToManyField. Related objects are only
serialized as references to the object's PK (i.e. the related *data*
is not dumped, just the relation).
"""
self._start_relational_field(field)
for relobj in getattr(obj, field.name).iterator():
self.xml.addQuickElement("object", attrs={"pk" : smart_unicode(relobj._get_pk_val())})
self.xml.endElement("field")
def _start_relational_field(self, field):
"""
Helper to output the <field> element for relational fields
"""
self.indent(2)
self.xml.startElement("field", {
"name" : field.name,
"rel" : field.rel.__class__.__name__,
"to" : smart_unicode(field.rel.to._meta),
})
class Deserializer(base.Deserializer):
"""
Deserialize XML.
"""
def __init__(self, stream_or_string, **options):
super(Deserializer, self).__init__(stream_or_string, **options)
self.event_stream = pulldom.parse(self.stream)
def next(self):
for event, node in self.event_stream:
if event == "START_ELEMENT" and node.nodeName == "object":
self.event_stream.expandNode(node)
return self._handle_object(node)
raise StopIteration
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 attribute, bail.
pk = node.getAttribute("pk")
if not pk:
raise base.DeserializationError("<object> node is missing the 'pk' attribute")
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)
def _handle_fk_field_node(self, node, field):
"""
Handle a <field> node for a ForeignKey
"""
# Check if there is a child node named 'None', returning None if so.
if node.getElementsByTagName('None'):
return None
else:
return field.rel.to._meta.get_field(field.rel.field_name).to_python(
getInnerText(node).strip())
def _handle_m2m_field_node(self, node, field):
"""
Handle a <field> node for a ManyToManyField.
"""
return [field.rel.to._meta.pk.to_python(
c.getAttribute("pk"))
for c in node.getElementsByTagName("object")]
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 getInnerText(node):
"""
Get all the inner text of a DOM node (recursively).
"""
# inspired by http://mail.python.org/pipermail/xml-sig/2005-March/011022.html
inner_text = []
for child in node.childNodes:
if child.nodeType == child.TEXT_NODE or child.nodeType == child.CDATA_SECTION_NODE:
inner_text.append(child.data)
elif child.nodeType == child.ELEMENT_NODE:
inner_text.extend(getInnerText(child))
else:
pass
return u"".join(inner_text)