Crash of GraphML export reported

[troeger]

The user sees HTTP error 500, this is happening in the backend:

Internal Server Error: /api/front/graphs/1485
Traceback (most recent call last):
 File "/var/www/fuzzed/venv/lib/python2.7/site-packages/django/core/handlers/base.py", line 132, in get_response
   response = wrapped_callback(request, *callback_args, **callback_kwargs)
 File "/var/www/fuzzed/venv/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
   return view_func(*args, **kwargs)
 File "/var/www/fuzzed/www/FuzzEd/api/common.py", line 345, in wrapper
   return self._handle_500(request, e)
 File "/var/www/fuzzed/venv/src/django-tastypie/tastypie/resources.py", line 289, in _handle_500
   return self.error_response(request, data, response_class=response_class)
 File "/var/www/fuzzed/venv/src/django-tastypie/tastypie/resources.py", line 1231, in error_response
   serialized = self.serialize(request, errors, desired_format)
 File "/var/www/fuzzed/venv/src/django-tastypie/tastypie/resources.py", line 371, in serialize
   return self._meta.serializer.serialize(data, format, options)
 File "/var/www/fuzzed/venv/src/django-tastypie/tastypie/serializers.py", line 202, in serialize
   serialized = getattr(self, "to_%s" % desired_format)(bundle, options)
 File "/var/www/fuzzed/www/FuzzEd/api/common.py", line 73, in to_graphml
   return data.obj.to_graphml()
AttributeError: 'dict' object has no attribute 'obj'_

It may be related to another exception floating in for the same graph, which relates to Unicode problems:

Internal Server Error: /api/front/graphs/1485
Traceback (most recent call last):
 File "/var/www/fuzzed/www/FuzzEd/api/common.py", line 275, in wrapper
   response = callback(request, *args, **kwargs)
 File "/var/www/fuzzed/venv/src/django-tastypie/tastypie/resources.py", line 442, in dispatch_detail
   return self.dispatch('detail', request, **kwargs)
 File "/var/www/fuzzed/venv/src/django-tastypie/tastypie/resources.py", line 465, in dispatch
   response = method(request, **kwargs)
 File "/var/www/fuzzed/venv/src/django-tastypie/tastypie/resources.py", line 1325, in get_detail
   return self.create_response(request, bundle)
 File "/var/www/fuzzed/venv/src/django-tastypie/tastypie/resources.py", line 1202, in create_response
   serialized = self.serialize(request, data, desired_format)
 File "/var/www/fuzzed/venv/src/django-tastypie/tastypie/resources.py", line 371, in serialize
   return self._meta.serializer.serialize(data, format, options)
 File "/var/www/fuzzed/venv/src/django-tastypie/tastypie/serializers.py", line 202, in serialize
   serialized = getattr(self, "to_%s" % desired_format)(bundle, options)
 File "/var/www/fuzzed/www/FuzzEd/api/common.py", line 73, in to_graphml
   return data.obj.to_graphml()
 File "/var/www/fuzzed/www/FuzzEd/models/graph.py", line 163, in to_graphml
   [edge.to_graphml() for edge in self.edges.filter(deleted=False)] +
 File "/var/www/fuzzed/www/FuzzEd/models/node.py", line 180, in to_graphml
   self.properties_to_graphml() +
 File "/var/www/fuzzed/www/FuzzEd/models/node.py", line 205, in properties_to_graphml
   graphml.append(self.graphml_data_key(prop.key, prop.get_value()))
 File "/var/www/fuzzed/www/FuzzEd/models/node.py", line 210, in graphml_data_key
   return '            <data key="%s">%s</data>\n' % (key, str(value))
UnicodeEncodeError: 'ascii' codec can't encode character u'\u2026' in position 0: ordinal not in range(128)