TypeError: NoneType object is not callable on GeoDjango

Question

Although I have read many similar articles about PointField and 'NoneType' object error, I can't figure out how this field should be automatically save according to the latitude and longitude variables I received from the user.

Here is my model:

    from django.db import models
    from django.contrib.gis.db import models
    from django.contrib.gis.geos import Point
    
    class Firm(models.Model):
        FirmName = models.CharField(max_length=50)
        address = models.CharField(max_length=1000, null=True, blank=True)
        FirmAddress = models.PointField(null=True, blank = True, geography=True, default=Point(0.0, 0.0))
        lat = models.FloatField(null=True, blank=True)
        lng = models.FloatField(null=True, blank=True)
        Logo = models.ImageField(null=True, blank=True)
    
        @property
        def save(self, *args, **kwargs):
            self.FirmAddress = Point(self.lng, self.lat)
            super(Firm, self).save(*args, **kwargs)

On the Django shell, I type from firm.models import Firm command first and then Firm.objects.create(FirmName="QWERTY", address="temp", lat=24, lng=54, Logo='logo.jpg') command.
Here is the error I got at the end:

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "C:\Users\Deniz\Desktop\PROJECT\fenv\lib\site-packages\django\db\models\manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Users\Deniz\Desktop\PROJECT\fenv\lib\site-packages\django\db\models\query.py", line 453, in create
    obj.save(force_insert=True, using=self.db)
TypeError: 'NoneType' object is not callable

But when I look at my database, I see that a value of type geography-point has been added to the FirmAddress column. When I remove the FirmAddress feature and update the model, I don't get any errors and everything works fine.

The part I'm having trouble understanding is, if FirmAddress data can be added to the database correctly, why am I getting the 'NoneType' object error? How can I fix this situation? Many thanks.

Answer 1

Why am I getting the 'NoneType' object error?

Because you defined save as a @property. As a result if you use self.save, it will call the save method, and self.save will take as value what the object returned, but that is None, hence the error.

You thus should remove the @property decorator:

class Firm(models.Model):
    # …
    
    # no property
    def save(self, *args, **kwargs):
        self.FirmAddress = Point(self.lng, self.lat)
        return super().save(*args, **kwargs)