Django Make Migration Error没有这样的列

Question

我有一个预先存在的模型，我现在正在尝试添加一个额外的字段。不是我创建了最初的字段，但我一直在向其他类添加字段，并使迁移变得很好。在

我想在类事件中添加一个额外的图像字段，这个类上已经有一个图像字段，所以我知道它可以处理图像字段，我已经尝试更改名称，看看这是否也是一个问题。下面是我要添加的字段：

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

这是在将代码添加到模型后尝试进行迁移时遇到的错误：

^{pr2}$

从我对迁移如何工作的理解来看，不应该有一个名为this的专栏，因为我还没有进行迁移，它将添加到数据库中。在

我也试着给字段添加一个默认值，但是没有成功。我还尝试过完全删除数据库以及迁移文件，并尝试重新创建它们。在

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)

回溯如下：

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

就在那里：

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))

你对一个应用程序的源代码进行查询，据我所知，它查询另一个应用程序的模型。如果可以避免的话，你不应该在应用程序安装中进行查询。如果必须或延迟加载，请使用信号。在

如果你真的必须这么做，那就改变应用程序的顺序。如果是同一个应用程序，那么是的，不要这样做：正如您所注意到的，您将无法进行任何迁移。在

Answer 2

此问题可能是由于数据库中可能不存在相应的图像字段。请登录数据库shell并检查是否有相应的字段。如果没有，则使用SQL查询或回滚到以前的安全迁移中手动添加，然后在中进行更改模型.py并生成迁移文件。在