Question

伙计们我得到一个错误，因为你应该对模型有一个默认值：author，body，created，updated 这是我的models.py配置

from django.db import models
from django.utils import timezone
from django.contrib.auth.models import User
# Create your models here.
class post(models.Model):
    STATUS_CHOICE=(
        ('draft','DRAFT'),
        ('published','Published'),
    )

    title=models.CharField(max_length=250)
    slug=models.SlugField(max_length = 250,unique_for_date=1)
    author=models.ForeignKey(User,related_name='blog_posts')
    body=models.TextField()
    publish=models.DateTimeField(default=timezone.now)
    created = models.DateTimeField(auto_now_add=True)
    updated=models.DateTimeField(auto_now=True)
    status = models.CharField(max_length=10,
                            choices = STATUS_CHOICE,
                                default='draft')
    class Meta:
        ordering = ('-publish',)
    def __str__(self):
        return self.title

这是迁移数据库时的错误：

You are trying to add a non-nullable field 'body' to post without a default; 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

我不确定这些型号的默认值是什么，配置与书中提到的相同，但我仍然收到错误任何形式的帮助表示赞赏提前致谢注意：这是一个博客应用程序当我试图向模型添加随机默认值时，我收到此错误：更新了models.py:

from django.db import models
from django.utils import timezone
from django.contrib.auth.models import User
# Create your models here.
class post(models.Model):
    STATUS_CHOICE=(
        ('draft','DRAFT'),
        ('published','Published'),
        ('admin','admin'),
    )

    title=models.CharField(max_length=250)
    slug=models.SlugField(max_length = 250)
    author=models.ForeignKey(User,related_name='blog_posts')
    body=models.TextField(default='draft')
    publish=models.DateTimeField(default=timezone.now)
    created = models.DateTimeField(auto_now_add=True,default=timezone.now)
    updated =models.DateTimeField(auto_now=True,default=timezone.now)
    status = models.CharField(max_length=10,
                            choices = STATUS_CHOICE,
                                default='draft')
    class Meta:
        ordering = ('-publish',)
    def __str__(self):
        return self.title

现在的错误是：

ERRORS:
myblog.post.created: (fields.E160) The options auto_now, auto_now_add, and default are mutually exclusive. Only one of these options may
 be present.
myblog.post.updated: (fields.E160) The options auto_now, auto_now_add, and default are mutually exclusive. Only one of these options may
 be present

Answer 1

为什么不使用null = True，blank = True - 允许模型属性为空！

我会将body属性的默认值设置为＆＃39;＆＃39;

body=models.TextField(default='')

时间戳不应该有默认值，你提供的callables应该足够了。

# Model Timestamp
created     = models.DateTimeField(auto_now_add=True)
updated     = models.DateTimeField(auto_now=True)

执行迁移时，它会为创建和更新的属性运行缺少的默认错误，请选择1）并在控制台中输入 timezone.now()。这会将现有行的默认值设置为当前日期时间。

从models.py

1 个答案: