我使用Django 1.9和MySQL。我想重命名模型中的字段。让我们来看看Django getting started tutorial中的Choice模型。
class Choice(models.Model):
question = models.ForeignKey(Question)
choice_text = models.CharField(max_length = 200)
votes = models.IntegerField(default=0)字符串
因此，我想将votes字段重命名为votes_count。我创建了一个空迁移，并添加到以下行的操作中：
migrations.RenameField (
model_name='choice',
old_name='votes',
new_name='votes_count',
),型
在python manage.py migrate之后，数据库表中的字段被重命名。但当我试图用这个模型
def vote(request, question_id):
question = get_object_or_404(Question, pk=question_id);
try:
selected = question.choice_set.get(pk=request.POST['choice'])
except (KeyError, Choice.DoesNotExist):
return render(request, 'polls/detail.html', {
'question':question,
'error_message':"You didn't select a choice."
})
else:
selected.votes_count += 1
selected.save()
return HttpResponseRedirect(reverse('polls:results', args=(question_id)))型
我得到了：
字段列表中的未知列“polls_choice.votes”
Traceback:
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
64. return self.cursor.execute(sql, params)
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/backends/mysql/base.py" in execute
112. return self.cursor.execute(query, args)
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
226. self.errorhandler(self, exc, value)
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/connections.py" in defaulterrorhandler
36. raise errorvalue
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
217. res = self._query(query)
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/cursors.py" in
_query
378. rowcount = self._do_query(q)
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/cursors.py" in
_do_query
341. db.query(q)
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/connections.py" in query
280. _mysql.connection.query(self, query)
The above exception ((1054, "Unknown column 'polls_choice.votes' in 'field list'")) was the direct cause of the following exception:
File "/home/verdigo/venv/lib/python3.4/site-packages/django/core/handlers/base.py" in get_response
149. response = self.process_exception_by_middleware(e, request)
File "/home/verdigo/venv/lib/python3.4/site-packages/django/core/handlers/base.py" in get_response
147. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "./polls/views.py" in vote
23. selected = question.choice_set.get(pk=request.POST['choice'])
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/models/manager.py" in manager_method
122. return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/models/query.py" in get
381. num = len(clone)
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/models/query.py" in __len__
240. self._fetch_all()
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/models/query.py" in _fetch_all
1074. self._result_cache = list(self.iterator())
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/models/query.py" in __iter__
52. results = compiler.execute_sql()
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/models/sql/compiler.py" in execute_sql
848. cursor.execute(sql, params)
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
79. return super(CursorDebugWrapper, self).execute(sql, params)
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
64. return self.cursor.execute(sql, params)
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/utils.py" in
__exit__
95. six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/home/verdigo/venv/lib/python3.4/site-packages/django/utils/six.py" in reraise
685. raise value.with_traceback(tb)
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
64. return self.cursor.execute(sql, params)
File "/home/verdigo/venv/lib/python3.4/site-packages/django/db/backends/mysql/base.py" in execute
112. return self.cursor.execute(query, args)
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
226. self.errorhandler(self, exc, value)
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/connections.py" in defaulterrorhandler
36. raise errorvalue
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
217. res = self._query(query)
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/cursors.py" in
_query
378. rowcount = self._do_query(q)
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/cursors.py" in
_do_query
341. db.query(q)
File "/home/verdigo/venv/lib/python3.4/site-packages/MySQLdb/connections.py" in query
280. _mysql.connection.query(self, query)
Exception Type: OperationalError at /polls/1/vote/
Exception Value: (1054, "Unknown column 'polls_choice.votes' in 'field list'")型
4条答案
按热度按时间a0x5cqrl1#
看起来好像您创建并运行了一个迁移，将模型字段从
votes重命名为votes_count，但没有同时更新模型。当Django试图从数据库中获取模型时，它试图选择
votes列，因为你的模型中仍然有一个votes字段，你会得到错误，因为该列在数据库中不存在。通常不需要创建手动迁移。通常，您会重命名模型字段，运行
makemigrations，然后运行migrate。让Django创建迁移的好处是，在运行migrate之后，您可以确信数据库与模型同步。bn31dyow2#
原因：当创建一个新的一对多外键，用forkey字段指向模型，然后生成表时，会发生此错误
.
解决方法：直接删除数据库，重新构建即可解决。
1：删除数据库数据库表;
2、删除后重新创建，之前创建的代码，直接运行
kh212irz3#
这个问题一直困扰着我，让我陷入了很多的困境，比如摔table等等。我发现的一个简单的解决方案是，当django问你是否要重命名该模型的一个字段时（运行makemigrations时），回答“N”。然后，它基本上执行的是删除您以前的字段并创建新字段。要小心，因为你可能会失去现有领域的数据，所以这与领域，无论是新的或相对容易'重新填充'他们所需的数据。如果你在makemigrations之后得到一个关于在迁移时不能“删除字段”的错误，你可能需要运行--fake。
更新：我对布尔字段做了上述操作，我的数据被保留了下来。尽管我说了N，但它似乎本质上是一个重命名。
cgh8pdjw4#
在我这边，当我添加一个具有oneToMany关系的新列时，迁移失败了。为了避免删除数据和重新创建模型，请下载适用于您的平台的mysql workbench。运行以下代码以插入缺少的列。
字符串
添加了缺少的列，错误就消失了