theonlykingpin/jsonfield

A reusable Django model field for storing ad-hoc JSON data

jsonfield

jsonfield is a reusable model field that allows you to store validated JSON, automatically handling serialization to and from the database. To use, add jsonfield.JSONField to one of your models.

Note: django.contrib.postgres now supports PostgreSQL's jsonb type, which includes extended querying capabilities. If you're an end user of PostgreSQL and want full-featured JSON support, then it is recommended that you use the built-in JSONField. However, jsonfield is still useful when your app needs to be database-agnostic, or when the built-in JSONField's extended querying is not being leveraged. e.g., a configuration field.

Requirements

jsonfield aims to support all current versions of Django, however the explicity tested versions are:

• Python: 3.6, 3.7, 3.8
• Django: 2.2, 3.0

Installation

pip install jsonfield

Usage

from django.db import models
from jsonfield import JSONField

class MyModel(models.Model):
    json = JSONField()

Querying

As stated above, JSONField is not intended to provide extended querying capabilities. That said, you may perform the same basic lookups provided by regular text fields (e.g., exact or regex lookups). Since values are stored as serialized JSON, it is highly recommended that you test your queries to ensure the expected results are returned.

Handling null values

A model field's null argument typically controls whether null values may be stored in its column by setting a not-null constraint. However, because JSONField serializes its values (including nulls), this option instead controls how null values are persisted. If null=True, then nulls are not serialized and are stored as a null value in the database. If null=False, then the null is instead stored in its serialized form.

This in turn affects how null values may be queried. Both fields support exact matching:

MyModel.objects.filter(json=None)

However, if you want to use the isnull lookup, you must set null=True.

class MyModel(models.Model):
    json = JSONField(null=True)

MyModel.objects.filter(json__isnull=True)

Note that as JSONField.null does not prevent nulls from being stored, achieving this must instead be handled with a validator.

Advanced Usage

By default python deserializes json into dict objects. This behavior differs from the standard json behavior because python dicts do not have ordered keys. To overcome this limitation and keep the sort order of OrderedDict keys the deserialisation can be adjusted on model initialisation:

import collections

class MyModel(models.Model):
    json = JSONField(load_kwargs={'object_pairs_hook': collections.OrderedDict})

Other Fields

jsonfield.JSONCharField

Subclasses models.CharField instead of models.TextField.

Running the tests

The test suite requires tox.

$ pip install tox

Then, run the tox command, which will run all test jobs.

$ tox

Or, to test just one job (for example Django 2.0 on Python 3.6):

$ tox -e py36-django20

Release Process

• Update changelog
• Update package version in setup.py
• Check supported versions in setup.py and readme
• Create git tag for version
• Upload release to PyPI test server
• Upload release to official PyPI server

$ pip install -U pip setuptools wheel twine
$ rm -rf dist/ build/
$ python setup.py sdist bdist_wheel
$ twine upload -r test dist/*
$ twine upload dist/*

Changes

Take a look at the changelog.