我删除了项目中的所有迁移，删除了数据库并尝试使用manage.py makemigrations命令重新创建迁移。
但是我收到了错误：
Traceback (most recent call last):
File "/Applications/PyCharm.app/Contents/helpers/pycharm/django_manage.py", line 41, in <module>
run_module(manage_file, None, '__main__', True)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/runpy.py", line 176, in run_module
fname, loader, pkg_name)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/runpy.py", line 82, in _run_module_code
mod_name, mod_fname, mod_loader, pkg_name)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/runpy.py", line 72, in _run_code
exec code in run_globals
File "/Users/rankor/src/python/web/Auction/Auction/manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/core/management/__init__.py", line 350, in execute_from_command_line
utility.execute()
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/core/management/__init__.py", line 342, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/core/management/base.py", line 348, in run_from_argv
self.execute(*args, **cmd_options)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/core/management/base.py", line 398, in execute
self.check()
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/core/management/base.py", line 426, in check
include_deployment_checks=include_deployment_checks,
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/core/checks/registry.py", line 75, in run_checks
new_errors = check(app_configs=app_configs)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/core/checks/urls.py", line 10, in check_url_config
return check_resolver(resolver)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/core/checks/urls.py", line 19, in check_resolver
for pattern in resolver.url_patterns:
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/utils/functional.py", line 33, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/core/urlresolvers.py", line 417, in url_patterns
patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/utils/functional.py", line 33, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/core/urlresolvers.py", line 410, in urlconf_module
return import_module(self.urlconf_name)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/importlib/__init__.py", line 37, in import_module
__import__(name)
File "/Users/rankor/src/python/web/Auction/Auction/Auction/urls.py", line 14, in <module>
url(r'^orders/', include('orders.urls', namespace='orders')),
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/conf/urls/__init__.py", line 52, in include
urlconf_module = import_module(urlconf_module)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/importlib/__init__.py", line 37, in import_module
__import__(name)
File "/Users/rankor/src/python/web/Auction/Auction/orders/urls.py", line 3, in <module>
from orders.views import CreateOrderView, OrdersView, OrderView
File "/Users/rankor/src/python/web/Auction/Auction/orders/views.py", line 7, in <module>
from orders.forms import OrderForm
File "/Users/rankor/src/python/web/Auction/Auction/orders/forms.py", line 47, in <module>
class OrderForm(ModelForm):
File "/Users/rankor/src/python/web/Auction/Auction/orders/forms.py", line 60, in OrderForm
widget=forms.Select, queryset=OrderCategory.objects.filter(parent__isnull=False).order_by('ordering'))
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/forms/models.py", line 1142, in __init__
self.queryset = queryset
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/forms/models.py", line 1168, in _set_queryset
self.widget.choices = self.choices
File "/Users/rankor/src/python/web/Auction/Auction/orders/forms.py", line 16, in _get_choices
if not self.queryset:
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/db/models/query.py", line 266, in __nonzero__
return type(self).__bool__(self)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/db/models/query.py", line 262, in __bool__
self._fetch_all()
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/db/models/query.py", line 1074, in _fetch_all
self._result_cache = list(self.iterator())
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/db/models/query.py", line 52, in __iter__
results = compiler.execute_sql()
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 852, in execute_sql
cursor.execute(sql, params)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/db/backends/utils.py", line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/db/utils.py", line 95, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/Users/rankor/src/python/web/Auction/lib/python2.7/site-packages/django/db/backends/sqlite3/base.py", line 323, in execute
return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: no such table: orders_ordercategory
OrderForm：
class OrderForm(ModelForm):
"""
Order form
"""
class Meta:
model = Order
fields = ('city', 'category', 'title', 'min_price', 'max_price', 'description', 'delivery_type', 'valid_to')
city = forms.ModelChoiceField(
widget=forms.Select, queryset=City.objects.filter(country__code='RU').order_by('name'))
category = CategoryChoiceField(
widget=forms.Select, queryset=OrderCategory.objects.filter(parent__isnull=False).order_by('ordering'))
valid_to = forms.DateField(widget=SelectDateWidget)
class GroupedModelChoiceField(forms.ModelChoiceField):
def optgroup_from_instance(self, obj):
return ""
def __choice_from_instance__(self, obj):
return obj.id, self.label_from_instance(obj)
def _get_choices(self):
if not self.queryset:
return []
all_choices = []
if self.empty_label:
current_optgroup = ""
current_optgroup_choices = [("", self.empty_label)]
else:
current_optgroup = self.optgroup_from_instance(self.queryset[0])
current_optgroup_choices = []
for item in self.queryset:
optgroup_from_instance = self.optgroup_from_instance(item)
if current_optgroup != optgroup_from_instance:
all_choices.append((current_optgroup, current_optgroup_choices))
current_optgroup_choices = []
current_optgroup = optgroup_from_instance
current_optgroup_choices.append(self.__choice_from_instance__(item))
all_choices.append((current_optgroup, current_optgroup_choices))
return all_choices
choices = property(_get_choices, forms.ChoiceField._set_choices)
class CategoryChoiceField(GroupedModelChoiceField):
def optgroup_from_instance(self, obj):
return obj.parent.title
为什么以及如何解决它？
P.S。 Django 1.9，python 2.7，OS X。
答案 0 :(得分：5)
查看堆栈跟踪。
在预热过程中，Django会导入所有模型和网址。
您应该将查询集初始化移动到OrderForm的 init 方法。
更一般的说明，并回答洛伦佐。在所有情况中，您希望将字段查询集初始化移动到表单的init方法或将其移动到您的视图中。为什么？实际上，当Django启动时，它可以导入一些表单，构建表单类，同样的字段类属性也会发生。因此，只要您不重新加载服务器，就会直接获取查询集，一劳永逸，只要您不重新加载服务器，保持不变，所以如果您曾经将数据添加到OrderCategory，它将永远不会出现在您的选择小部件中。
＆＃34;解决方法＆＃34;是将查询集初始化移动到表单的init方法。
在你的情况下：
class OrderForm(ModelForm):
def __init__(self, *args, **kwargs):
super(OrderForm, self).__init__(*args, **kwargs)
self.fields['city'].queryset = City.objects.filter(country__code='RU').order_by('name')
self.fields['category'].queryset = OrderCategory.objects.filter(parent__isnull=False).order_by('ordering')
class Meta:
#...
# ... fields definition
有关相关Django文档，请参阅Fields which handle relationships。