Question

我有一个预先存在的模型，我现在也想添加一个额外的字段。创建原始字段并不是我，但我一直在为其他类添加字段并使迁移变得很好。

我想在类Event中添加一个额外的图像字段，这个类上已有一个图像字段，所以我知道它可以处理图像字段，我试过更改名称，看看是否也是一个问题。这是我要添加的字段：

social_media_image = models.ImageField(null=True, blank=True, help_text='Hello World')

这是我在将该代码添加到模型后尝试进行迁移时遇到的错误：

django.db.utils.OperationalError: no such column: posts_event.social_media_image

根据我对迁移工作原理的理解，不应该有一个名为this的列，因为我尚未进行迁移，而是将其添加到数据库中。

我也试过在字段中添加默认值，但没有运气。我还尝试完全删除数据库以及迁移文件并尝试重新创建它们。

以下是模型中的其他字段：

slug = AutoSlugField(max_length=50, unique=True, populate_from='title')
content = models.TextField(default='')
start_time = models.DateTimeField()
image = models.ImageField(null=True, blank=True, help_text=image_help_text)

这是追溯：

Traceback (most recent call last):
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/db/backends/sqlite3/base.py", line 337, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: no such column: posts_event.social_media_image

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/core/management/__init__.py", line 367, in execute_from_command_line
    utility.execute()
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/core/management/__init__.py", line 341, in execute
    django.setup()
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/__init__.py", line 27, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/apps/registry.py", line 115, in populate
    app_config.ready()
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/source/enfield_presents/posts/apps.py", line 37, in ready
    search.register(Event.objects.get_upcoming_events(site_id=settings.SITE_ID, include_spektrix=False, return_queryset=True))
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/source/enfield_presents/posts/models.py", line 282, in get_upcoming_events
    events_with_a_next_start_time = [e for e in events if e.next_start_time() is not None]
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/db/models/query.py", line 256, in __iter__
    self._fetch_all()
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/db/models/query.py", line 1087, in _fetch_all
    self._result_cache = list(self.iterator())
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/db/models/query.py", line 54, in __iter__
    results = compiler.execute_sql()
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 835, in execute_sql
    cursor.execute(sql, params)
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/db/backends/utils.py", line 79, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/venv/lib/python3.4/site-packages/django/db/backends/sqlite3/base.py", line 337, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: no such column: posts_event.social_media_image

Answer 1

此问题可能是由于相应的Image字段可能不存在于数据库中的原因所致。请登录到数据库外壳，并检查是否存在相应的字段。如果没有，请使用SQL查询手动添加它或回滚到以前的安全迁移，然后在models.py中进行更改并生成迁移文件。

Answer 2

就在这里

File "/Applications/XAMPP/xamppfiles/htdocs/enfield/enfield-presents/source/enfield_presents/posts/apps.py", line 37, in ready:
search.register(Event.objects.get_upcoming_events(site_id=settings.SITE_ID, include_spektrix=False, return_queryset=True))

您对一个应用程序的源执行查询集，据我所知，它查询另一应用程序的模型。如果可以避免，则不应在应用设置中进行查询。如果必须加载或延迟加载，请使用信号。

如果确实需要，请翻转应用程序的顺序。如果是同一应用程序，则可以，请不要这样做：您会注意到，您将无法进行任何迁移。

Django使迁移错误没有这样的列

2 个答案: