Django serialize datetime to json in QuerySet/Dict

Question

I've tried to serialize QuerySet or Dict object with datetime.date object in the following ways:

Way #1:

json.dumps(MyModel.objects.values())

Raises error:

Exception Value: [{'date': datetime.date(2012, 5, 26), 'time': datetime.time(0, 42, 27)}] is not JSON serializable

Way #2:

json.dumps(MyModel.objects.values(), cls=DjangoJSONEncoder)

Also raises error:

Exception Value: [{'date': datetime.date(2012, 5, 26), 'time': datetime.time(0, 42, 27)}] is not JSON serializable

Way #3:

json.dumps(MyModel.objects.all(), cls=DjangoJSONEncoder)

Exception Value: [< MyModel: MyModel object>] is not JSON serializable

Way #4:

serializers.serialize('json', MyModel.objects.all())

Raises error:

Exception Value: 'str' object has no attribute '_meta'

How to serialize object with datetime's field to JSON in Django?

Answer 1

Your issue has nothing to do with datetimes. It's simply that querysets are not by themselves directly serializable, even with the DjangoJSONEncoder class and even using values() . You'll get exactly the same result with a model with no datetime fields at all.

The way you're supposed to do serialization in Django is to use serializers :

from django.core import serializers
output = serializers.serialize('json', MyModel.objects.all())

But no doubt you're trying to avoid that because the output format is so unnecessarily complex. Instead, I usually use the 'python' serializer to convert to a dict, then dump to json:

temp_output = serializers.serialize('python', MyModel.objects.all())
output = json.dumps(temp_output, cls=DjangoJSONEncoder)

Answer 2

If you want to just dump a dictionary to JSON, just use json.dumps. It can easily be made to serialize objects by passing in a custom serialization class - there's one included with Django that deals with datetimes already:

from django.core.serializers.json import DjangoJSONEncoder
json.dumps(mydict, cls=DjangoJSONEncoder)

Answer 3

This is the way i have retrieved datetime in json format,

from django.core import serializers
_data = serializers.serialize('json', MyModel.objects.all())
bi_data = [i.get('fields', i) for i in json.loads(_data) if i]