app/django/core/serializers/json.py
author Madhusudan C.S <madhusudancs@gmail.com>
Sat, 25 Jul 2009 01:09:46 +0530
changeset 2679 0ede2f3adbc1
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
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

"""
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