Django在根据models生成数据库表时报 __init__() missing 1 required positional argument: 'on_delete'

在django创建modules时出现以下错误

Failed to get real commands on module "blog_project": python process died with code 1: Traceback (most recent call last):
  File "D:PyCharm 2016.3helperspycharm\_jb_manage_tasks_provider.py", line 25, in <module>
    django.setup()
  File "D:Python35libsite-packagesdjango-2.0-py3.5.eggdjango\__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "D:Python35libsite-packagesdjango-2.0-py3.5.eggdjangoapps
egistry.py", line 112, in populate
    app_config.import_models()
  File "D:Python35libsite-packagesdjango-2.0-py3.5.eggdjangoappsconfig.py", line 198, in import_models
    self.models_module = import_module(models_module_name)
  File "D:Python35libimportlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 665, in exec_module
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "D:pythonWorkStationlog_projectlogmodels.py", line 62, in <module>
    class Article(models.Model):
  File "D:pythonWorkStationlog_projectlogmodels.py", line 69, in Article
    user = models.ForeignKey(User, verbose_name='用户')
TypeError: __init__() missing 1 required positional argument: 'on_delete'

对应module的语句

class Article(models.Model):
    title = models.CharField(max_length=50, verbose_name='文章标题')
    desc = models.CharField(max_length=50, verbose_name='文章描述')
    content = models.TextField(verbose_name='文章内容')
    click_count = models.IntegerField(default=0, verbose_name='点击次数')
    is_recommend = models.BooleanField(default=False, verbose_name='是否推荐')
    date_publish = models.DateTimeField(auto_now_add=True, verbose_name='发布时间')
    user = models.ForeignKey(User, verbose_name='用户')
    category = models.ForeignKey(Category, blank=True, null=True, verbose_name='分类')
    tag = models.ManyToManyField(Tag, verbose_name='标签')

    objects = ArticleManager()

需要在第8行加上,on_delete=models.CASCADE，则问题解决

---

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class Article(models.Model):
    title = models.CharField(max_length=50, verbose_name='文章标题')
    desc = models.CharField(max_length=50, verbose_name='文章描述')
    content = models.TextField(verbose_name='文章内容')
    click_count = models.IntegerField(default=0, verbose_name='点击次数')
    is_recommend = models.BooleanField(default=False, verbose_name='是否推荐')
    date_publish = models.DateTimeField(auto_now_add=True, verbose_name='发布时间')
    user = models.ForeignKey(User, verbose_name='用户',on_delete=models.CASCADE,)
    category = models.ForeignKey(Category, blank=True, null=True, verbose_name='分类',on_delete=models.CASCADE,)
    tag = models.ManyToManyField(Tag, verbose_name='标签')

    objects = ArticleManager()

    class Meta:
        verbose_name = '文章'
        verbose_name_plural = verbose_name
        ordering = ['-date_publish']

    def __unicode__(self):
        return self.title