Code

Ticket #12914: pyyaml.py-svn-modified

File pyyaml.py-svn-modified, 2.2 KB (added by Beuc, 4 years ago)

Use yaml faster C implementation when available

Line 
1"""
2YAML serializer.
3
4Requires PyYaml (http://pyyaml.org/), but that's checked for in __init__.
5"""
6
7from StringIO import StringIO
8import decimal
9import yaml
10
11from django.db import models
12from django.core.serializers.python import Serializer as PythonSerializer
13from django.core.serializers.python import Deserializer as PythonDeserializer
14
15# Use the C (faster) implementation if possible
16try:
17    from yaml import CLoader as Loader
18    from yaml import CSafeDumper as SafeDumper
19except ImportError:
20    from yaml import Loader, SafeDumper
21
22class DjangoSafeDumper(SafeDumper):
23    def represent_decimal(self, data):
24        return self.represent_scalar('tag:yaml.org,2002:str', str(data))
25
26DjangoSafeDumper.add_representer(decimal.Decimal, DjangoSafeDumper.represent_decimal)
27
28class Serializer(PythonSerializer):
29    """
30    Convert a queryset to YAML.
31    """
32
33    internal_use_only = False
34
35    def handle_field(self, obj, field):
36        # A nasty special case: base YAML doesn't support serialization of time
37        # types (as opposed to dates or datetimes, which it does support). Since
38        # we want to use the "safe" serializer for better interoperability, we
39        # need to do something with those pesky times. Converting 'em to strings
40        # isn't perfect, but it's better than a "!!python/time" type which would
41        # halt deserialization under any other language.
42        if isinstance(field, models.TimeField) and getattr(obj, field.name) is not None:
43            self._current[field.name] = str(getattr(obj, field.name))
44        else:
45            super(Serializer, self).handle_field(obj, field)
46
47    def end_serialization(self):
48        self.options.pop('stream', None)
49        self.options.pop('fields', None)
50        self.options.pop('use_natural_keys', None)
51        yaml.dump(self.objects, self.stream, Dumper=DjangoSafeDumper, **self.options)
52
53    def getvalue(self):
54        return self.stream.getvalue()
55
56def Deserializer(stream_or_string, **options):
57    """
58    Deserialize a stream or string of YAML data.
59    """
60    if isinstance(stream_or_string, basestring):
61        stream = StringIO(stream_or_string)
62    else:
63        stream = stream_or_string
64    for obj in PythonDeserializer(yaml.load(stream, Loader=Loader), **options):
65        yield obj
66