RuntimeError: Model class payments_app.models.Product doesn't declare an explicit app_label and isn't in an application in INSTALLED_APPS.
When it says "Model class xxx doesn't declare an explicit app_label" your models can specify Meta to define their app_label. You can also customise the database table name along with a bunch of other options as part of the meta data.
Example: If your application name is user_app
You need to do something like this on all your models;
class Author(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
profile_picture = models.ImageField()
class Meta:
app_label = 'user_app'
def __str__(self):
return self.user.username