1. 发生了什么事。深入源代码时，
   。我们可以看到以下调用堆栈：

    1) form.is_valid() 
       ->form.full_clean()
        -->form._clean_fields()
         ---> self.cleand_data[name] = field.clean(value)
    2) field.clean(value)
        -> self.to_python(value)
        -> self.validate(value)

查看源代码时，您会发现，这主要是因为 empty_values 支票。

when look into the source code ,you can find that,it's mainly because the empty_values check.

# These values, if given to validate(), will trigger the self.required check.
EMPTY_VALUES = (None, '', [], (), {})

如您所见，空字典 {} 是JSONField的空值。

as you can see the empty dict {} is as an empty value for JSONField. so it will raise Error.

1. 我们该怎么办？
   解决方案是自定义models.JSONField和form.JSONField，如下所示。

forms.py

from django.contrib.postgres import forms

class MyJSONField(forms.JSONField):
    empty_values = [None, "", [], ()]

db /fields.py

db/fields.py

class MyJSONField(JSONField):
    def formfield(self, **kwargs):
        from ..forms import MyJSONField

        return super().formfield(**{"form_class": MyJSONField, **kwargs})