ipython.out

In [1]: j = JsonModel.objects.create(data={'some': 'data'})

In [2]: j.id
Out[2]: 1

In [3]: repr(j.data)
Out[3]: "{'some': 'data'}"

In [4]: j.save()

In [5]: j = JsonModel.objects.get(id=1)

In [6]: repr(j.data)
Out[6]: '\'{"some": "data"}\''

In [7]: j.save()

In [8]: j = JsonModel.objects.get(id=1)

In [9]: repr(j.data)
Out[9]: '\'"{\\\\"some\\\\": \\\\"data\\\\"}"\''

models.py

from django.contrib.postgres.fields import JSONField
from django.db import models


class JsonModel(models.Model):
    data = JSONField()