CODEWITHSUNDEEP
pythondjangodjango-serializer
maraujop
maraujop

Reputation: 4594

Django JSON custom serializing losing datetime type

I'm encoding data fetched from a Django cursor using Django json libraries, however I'm seeing datetimes after deserializing are now unicode type. Simple example:

import datetime
from django.core.serializers.json import json, DjangoJSONEncoder


today = datetime.datetime.now()
encoded = json.dumps(today, cls=DjangoJSONEncoder)
type(json.loads(encoded))
>> unicode

If I'm not mistaken variable types should be respected. Then I thought maybe there was something like a DjangoJSONDecoder, but nothing. what am I doing wrong? is this the expected behavior?

Upvotes: 7

Views: 7032

Answers (2)

Daniel Roseman
Daniel Roseman

Reputation: 599600

It can't work how you think it should. The point is that JSON has no native type for dates/times, which is why the Django serializer converts datetimes to strings. But, of course, once they're strings, then they're strings; the deserializer has no way of knowing that they were once datetimes. You could, if you like, write a further custom deserializer that attempts to call strptime on each string, to see if it "should" be a datetime; but the overhead will be huge, and (depending on your data) could be subject to false positives.

Upvotes: 10

Pawel Furmaniak
Pawel Furmaniak

Reputation: 4806

You did not specify custom decoder class for json.loads (cls kwarg)

Upvotes: 1

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