Adds to Melange a tags framework based on taggable-mixin.
The taggable-mixin allowed only tag per Datastore model. This is extended
framework allows any arbitrary number of tags per Datastore model. Also,
now one can define different models for different Tag types which are all
inherited from the base Tag model provided by taggable-mixin.
The GHOPTask model makes use of 2 tags per model, one for difficulty and the
other for task_type, both using the tags framework.
Reviewed by: Paweł Sołyga
"""
YAML serializer.
Requires PyYaml (http://pyyaml.org/), but that's checked for in __init__.
"""
from StringIO import StringIO
import yaml
from django.db import models
from django.core.serializers.python import Serializer as PythonSerializer
from django.core.serializers.python import Deserializer as PythonDeserializer
class Serializer(PythonSerializer):
"""
Convert a queryset to YAML.
"""
internal_use_only = False
def handle_field(self, obj, field):
# A nasty special case: base YAML doesn't support serialization of time
# types (as opposed to dates or datetimes, which it does support). Since
# we want to use the "safe" serializer for better interoperability, we
# need to do something with those pesky times. Converting 'em to strings
# isn't perfect, but it's better than a "!!python/time" type which would
# halt deserialization under any other language.
if isinstance(field, models.TimeField) and getattr(obj, field.name) is not None:
self._current[field.name] = str(getattr(obj, field.name))
else:
super(Serializer, self).handle_field(obj, field)
def end_serialization(self):
self.options.pop('stream', None)
self.options.pop('fields', None)
yaml.safe_dump(self.objects, self.stream, **self.options)
def getvalue(self):
return self.stream.getvalue()
def Deserializer(stream_or_string, **options):
"""
Deserialize a stream or string of YAML data.
"""
if isinstance(stream_or_string, basestring):
stream = StringIO(stream_or_string)
else:
stream = stream_or_string
for obj in PythonDeserializer(yaml.load(stream)):
yield obj