The issue is similar to this bug that has been fixed:
https://code.djangoproject.com/ticket/24428 however doesn't seem to be due
to coercion. I've discovered this when trying to update a project from
django 2.2 to 3.2
test case to reproduce (in a new django project/app)
```
from django.db import models
from django.forms import ModelForm
class Vehicle(models.Model):
modifications = models.JSONField(default=list, blank=True, null=True)
class VehicleForm(ModelForm):
class Meta:
model = Vehicle
fields = ("modifications", )
def test_vehicle_form():
vehicle = Vehicle.objects.create()
assert vehicle.modifications == []
data = {"modifications": "[]"}
form = VehicleForm(data, instance=vehicle)
assert form.is_valid()
assert not form.has_changed()
```
I would expect that test to pass, but it doesn't. I'm not sure exactly
where the error lies, but I have discovered the following:
```
field.show_hidden_initial == True
field.to_python(hidden_widget.value_from_datadict(self.data, self.files,
initial_prefixed_name)) == None
```
which then fails the check in field.has_changed
```
initial_value = initial if initial is not None else ''
data_value = data if data is not None else ''
return initial_value != data_value
```
because `data == []`
--
You received this message because you are subscribed to the Google Groups
"Django users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to django-users+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-users/CAFy-P0f5xB-CHiSSO50KAHmHNn6ha5nUEO-coOPj67zAZ00qhg%40mail.gmail.com.
