app/django/core/serializers/json.py
author Sverre Rabbelier <srabbelier@gmail.com>
Sun, 19 Apr 2009 17:42:44 +0000
changeset 2246 c29272f640b0
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Tweak the 'load balancing' algorithm In order to reduce contention we randomly skipped jobs, but this caused many jobs to end up stopping early. Now instead we keep on going until we time out (also increased the chance of doing work). Patch by: Sverre Rabbelier

"""
Serialize data to/from JSON
"""

import datetime
from StringIO import StringIO

from django.core.serializers.python import Serializer as PythonSerializer
from django.core.serializers.python import Deserializer as PythonDeserializer
from django.utils import datetime_safe
from django.utils import simplejson

try:
    import decimal
except ImportError:
    from django.utils import _decimal as decimal    # Python 2.3 fallback

class Serializer(PythonSerializer):
    """
    Convert a queryset to JSON.
    """
    internal_use_only = False

    def end_serialization(self):
        self.options.pop('stream', None)
        self.options.pop('fields', None)
        simplejson.dump(self.objects, self.stream, cls=DjangoJSONEncoder, **self.options)

    def getvalue(self):
        if callable(getattr(self.stream, 'getvalue', None)):
            return self.stream.getvalue()

def Deserializer(stream_or_string, **options):
    """
    Deserialize a stream or string of JSON data.
    """
    if isinstance(stream_or_string, basestring):
        stream = StringIO(stream_or_string)
    else:
        stream = stream_or_string
    for obj in PythonDeserializer(simplejson.load(stream)):
        yield obj

class DjangoJSONEncoder(simplejson.JSONEncoder):
    """
    JSONEncoder subclass that knows how to encode date/time and decimal types.
    """

    DATE_FORMAT = "%Y-%m-%d"
    TIME_FORMAT = "%H:%M:%S"

    def default(self, o):
        if isinstance(o, datetime.datetime):
            d = datetime_safe.new_datetime(o)
            return d.strftime("%s %s" % (self.DATE_FORMAT, self.TIME_FORMAT))
        elif isinstance(o, datetime.date):
            d = datetime_safe.new_date(o)
            return d.strftime(self.DATE_FORMAT)
        elif isinstance(o, datetime.time):
            return o.strftime(self.TIME_FORMAT)
        elif isinstance(o, decimal.Decimal):
            return str(o)
        else:
            return super(DjangoJSONEncoder, self).default(o)

# Older, deprecated class name (for backwards compatibility purposes).
DateTimeAwareJSONEncoder = DjangoJSONEncoder