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"""
YAML serializer.
Requires PyYaml (http://pyyaml.org/), but that's checked for in __init__.
"""
from StringIO import StringIO
import decimal
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 DjangoSafeDumper(yaml.SafeDumper):
def represent_decimal(self, data):
return self.represent_scalar('tag:yaml.org,2002:str', str(data))
DjangoSafeDumper.add_representer(decimal.Decimal, DjangoSafeDumper.represent_decimal)
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)
self.options.pop('use_natural_keys', None)
yaml.dump(self.objects, self.stream, Dumper=DjangoSafeDumper, **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), **options):
yield obj
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