An empty list is considered as an empty value for JSONField.

[Dave White]

Environment: Django 3.1.5, Python 3.8.7, MariaDB 10.5.6

Expected behavior: I should be able to edit an object that contains a JSONField with default=list without having any validation errors if I save without changing the JSONField.

Steps to reproduce:

1. Define a field in an Object using models.JSONField(default=list).
2. Create a new Object.
3. Go to edit view of that Object in Django Admin. You will see the default [] empty list in the JSONField. Don’t change any field.
4. Click Save; without having changed anything, you’ll receive a validation error that “This field is required”
5. Workaround: put quotes around the "[]” or replace with any valid JSON object. If you try to put random characters in the field you'll receive a "Enter a valid JSON." validation.

Note: This bug seems similar to #31157 ​https://groups.google.com/g/django-updates/c/BshBo_jmUTA/m/Lu2ZY9mDCQAJ

Cheers,
Dave White

[Mariusz Felisiak]

This is not related with #31157. An empty list is an empty value for JSONField.

Duplicate of #26391. Feel-free to add a comment to the original ticket.