django 修改模型文件后 You are trying to add a non-nullable field ‘-----‘ to person without a default；

#原模型文件 first_name = models.CharField(max_length=50) last_name = models.CharField(max_length=50) #现模型文件 first_name = models.CharField(max_length=50) last_name = models.CharField(max_length=50) birth_date = models.DateField()

修改模型文件后，代码

python manage.py makemigrations python manage.py migrate

报错，

You are trying to add a non-nullable field '----' to person without a default; we can't do that (the database needs something to populate existing rows).

。解决措施

先赋予其默认值

#第一步 赋予默认值 first_name = models.CharField(max_length=50) last_name = models.CharField(max_length=50) birth_date = models.DateField(default='2001-01-01') #第二步 python manage.py makemigrations python manage.py migrate #第三步 first_name = models.CharField(max_length=50) last_name = models.CharField(max_length=50) birth_date = models.DateField()