django在model中添加字段報錯

在以下類中添加 description 字段后，

class Colors(models.Model):
    colors = models.CharField(u'顏色', max_length=10)
    description = models.CharField(u'描述', max_length=10)
    def __str__(self):
        return self.colors

　

執行以下初始化數據庫的步驟，報錯

C:\PycharmProjects\HelloWorld>python manage.py makemigrations
You are trying to add a non-nullable field 'description' to colors without a def
ault; we can't do that (the database needs something to populate existing rows).

Please select a fix:
 1) Provide a one-off default now (will be set on all existing rows with a null
value for this column)
 2) Quit, and let me add a default in models.py
Select an option: 

這個可能是之前已創建了表中的一條記錄，之后模型中增加了一個非空的字段，但是原來已經存在的記錄沒有這個值

解決方案1：

修改字段為允許為空  null=True

class Colors(models.Model):
    colors = models.CharField(u'顏色', max_length=10)
    description = models.CharField(u'描述', max_length=10,null=True)
    def __str__(self):
        return self.colors

　　

解決方案2：

先刪除整個migrations文件夾，再執行python manage.py makemigrations,和python manage.py migrate命令