id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
20090	SubfieldBase/to_python handles both serialized and original string which breaks custom model fields like JSONField	bjasper@…	nobody	"When using a custom model field liked JSONField (a field that lets you store validated JSON in your model), the way to_python() method handles both the serialized and original string makes it difficult (impossible?) to determine which case we're handling––so we never know if a string is still encoded JSON or has already been decoded.

This is a problem, for example, when storing raw numbers.

If I store the raw number 13, I'll get back the number 13.

But if I store the string ""13"", I'll still get back the number 13. This is because to_python() receives the ""13"", see's it's a string, thinks it's JSON, and decodes it.

It doesn't know if ""13"" should be returned as a string or returned as a number since to_python() doesn't know the context in which it's being called.

The only way we've found to get around this on our end is to prepend JSON encoded strings with the text ""json:"". This way we'd know for sure if a string was still encoded JSON. This is a big hack, so we'd like to avoid it as much as possible.

I have some tests but they are tied to the existing test suite––hope that's OK:

git clone -b broken_to_python https://github.com/bradjasper/django-jsonfield.git
cd broken_to_python
python setup.py test

Original discussion started here: https://github.com/bradjasper/django-jsonfield/issues/33"	Bug	closed	Uncategorized	1.4	Normal	invalid	subfieldbase to_python custom field json jsonfield	Jacob Rief	Unreviewed	0	0	0	0	0	0