没有Null约束失败-null =已设置真

Question

I am changing my register model so that there is a foreign key referencing a location. What I want to achieve, is to have a relationship where the Register model can have 0 to many locations.

Originally I set a manytomany field which I realised was a mistake as it gives each Register all of the locations in existence. I just want a subset for each Register.

My model now looks like:

class Register(AbstractBaseUser, models.Model):
    username = models.CharField(max_length=20,default='',blank=True)
    password = models.CharField(max_length=80,default='',blank=True)
    email = models.CharField(max_length=255,default='',blank=True)
    #Added 2nd May
    #locations = models.ManyToManyField(Location)
    #3rd May change to foreign key
    locations = models.ForeignKey(Location,on_delete=models.CASCADE, blank=True, null=True, default='')

    USERNAME_FIELD = 'username'

The model referenced is:

class Location(models.Model):
    locationname = models.CharField(max_length=80,default='',blank=True)
    address = models.ForeignKey(Address, on_delete=models.CASCADE)
    geolocation = models.ForeignKey(GeoLocation, on_delete=models.CASCADE, default='')

When I try to migrate I get the error below. I have ran makemigrations and if I run it again it states there are no changes.

"NOT NULL constraint failed: register_register.locations_id"

I have been searching other posts and it suggested adding the null=True argument which I have added, but I still get this error. I can't find any posts where this has been done and it still gives this error.

Answer 1

Purging the data from the database using manage.py flush allowed me to re-migrate the projects.

I realised that I had made a mistake with the relationship and had the Foreign key on the wrong table, it needed to be on location so that was fundamentally the issue.