django/core/serializers/pyyaml.py

   1 """
   2 YAML serializer.
   3
   4 Requires PyYaml (http://pyyaml.org/), but that's checked for in __init__.
   5 """
   6
   7 from django.db import models
   8 from django.core.serializers.python import Serializer as PythonSerializer
   9 from django.core.serializers.python import Deserializer as PythonDeserializer
  10 try:
  11     from cStringIO import StringIO
  12 except ImportError:
  13     from StringIO import StringIO
  14 import yaml
  15
  16 class Serializer(PythonSerializer):
  17     """
  18     Convert a queryset to YAML.
  19     """
  20
  21     internal_use_only = False
  22
  23     def handle_field(self, obj, field):
  24         # A nasty special case: base YAML doesn't support serialization of time
  25         # types (as opposed to dates or datetimes, which it does support). Since
  26         # we want to use the "safe" serializer for better interoperability, we
  27         # need to do something with those pesky times. Converting 'em to strings
  28         # isn't perfect, but it's better than a "!!python/time" type which would
  29         # halt deserialization under any other language.
  30         if isinstance(field, models.TimeField) and getattr(obj, field.name) is not None:
  31             self._current[field.name] = str(getattr(obj, field.name))
  32         else:
  33             super(Serializer, self).handle_field(obj, field)
  34
  35     def end_serialization(self):
  36         self.options.pop('stream', None)
  37         self.options.pop('fields', None)
  38         yaml.safe_dump(self.objects, self.stream, **self.options)
  39
  40     def getvalue(self):
  41         return self.stream.getvalue()
  42
  43 def Deserializer(stream_or_string, **options):
  44     """
  45     Deserialize a stream or string of YAML data.
  46     """
  47     if isinstance(stream_or_string, basestring):
  48         stream = StringIO(stream_or_string)
  49     else:
  50         stream = stream_or_string
  51     for obj in PythonDeserializer(yaml.load(stream)):
  52         yield obj
  53