在我运行＆＃34; makemigrations new_project＆＃34;之后，我第一次尝试在新创建的Django 1.9项目上进行迁移。迁移已创建，但是当我运行＆＃34; migrate命令时，我得到一个django.db.utils.OperationalError，用于导入我在forms.py文件中创建的模型。
我的models.py文件：
from django.db import models
from django.conf import settings
from django.utils.translation import ugettext_lazy as _
class Dealership(models.Model):
country = models.ForeignKey(Country)
name = models.CharField(max_length=100)
address = models.CharField(max_length=255)
postal_address = models.CharField(max_length=255, null=True, blank=True)
gps_x = models.FloatField()
gps_y = models.FloatField()
slug = SlugField(max_length=255, original_field='name')
def __str__(self):
return self.name
我的forms.py文件：
import re
from datetime import date, datetime
from django import forms
from django.conf import settings
from django.core.mail import EmailMessage
from django.core.validators import validate_email
from django.forms import extras
from django.utils.translation import ugettext_lazy as _
from new_project.models import Dealership
form ContactForm(forms.Form):
DEALERSHIPS = []
DEALERSHIPS.append(("", ("Select a dealer")))
for dealer in Dealership.objects.all():
DEALERSHIPS.append((dealer.name, _(dealer.name)))
dealer = forms.ChoiceField(
choices=DEALERSHIPS,
label="Service Center",
required=True)
....
错误抛出：＆＃34; ContactForm（forms.Form）：＆＃34; 这是错误日志：
Unhandled exception in thread started by <function wrapper at 0xb65e9064>
Traceback (most recent call last):
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/utils/autoreload.py", line 226, in wrapper
fn(*args, **kwargs)
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/core/management/commands/runserver.py", line 116, in inner_run
self.check(display_num_errors=True)
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/core/management/base.py", line 426, in check
include_deployment_checks=include_deployment_checks,
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/core/checks/registry.py", line 75, in run_checks
new_errors = check(app_configs=app_configs)
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/core/checks/urls.py", line 10, in check_url_config
return check_resolver(resolver)
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/core/checks/urls.py", line 19, in check_resolver
for pattern in resolver.url_patterns:
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/utils/functional.py", line 33, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/core/urlresolvers.py", line 417, in url_patterns
patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/utils/functional.py", line 33, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/core/urlresolvers.py", line 410, in urlconf_module
return import_module(self.urlconf_name)
File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
__import__(name)
File "/home/jcraine/Desktop/projects/new-project/src/new_project/urls.py", line 6, in <module>
from new_project import views
File "/home/jcraine/Desktop/projects/new-project/src/new_project/views.py", line 19, in <module>
from new_project.forms import ContactForm, RequestTestDriveForm, \
File "/home/jcraine/Desktop/projects/new-project/src/new_project/forms.py", line 72, in <module>
class RequestTestDriveForm(forms.Form):
File "/home/jcraine/Desktop/projects/new-project/src/new_project/forms.py", line 78, in RequestTestDriveForm
for dealer in Dealership.objects.all():
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/db/models/query.py", line 258, in __iter__
self._fetch_all()
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/db/models/query.py", line 1074, in _fetch_all
self._result_cache = list(self.iterator())
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/db/models/query.py", line 52, in __iter__
results = compiler.execute_sql()
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 852, in execute_sql
cursor.execute(sql, params)
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/db/utils.py", line 95, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/home/jcraine/Desktop/projects/new-project/env/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/home/jcraine/Desktop/projects/new-project/env/local/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: new_project_dealership
有没有人知道如何解决这个问题？提前谢谢。
修改
这是我的settings.py文件：
import os
from django.contrib.messages import constants as message_constants
from django.utils.translation import ugettext_lazy as _
BASE_DIR = os.path.dirname(os.path.dirname(__file__))
SECRET_KEY = 'xy89(rhki@zxc7#)hsfauh!v1^9#^dxs8u@xt8_jo#wt)iqrn)'
DEBUG = True
TEMPLATE_DEBUG = True
ALLOWED_HOSTS = []
INSTALLED_APPS = (
'grappelli',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'new_project',
)
MIDDLEWARE_CLASSES = (
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'corsheaders.middleware.CorsMiddleware',
'django.middleware.locale.LocaleMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware'
)
ROOT_URLCONF = 'new_project.urls'
WSGI_APPLICATION = 'new_project.wsgi.application'
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.sqlite3',
'NAME': os.path.join(BASE_DIR, '..', 'data', 'db.sqlite3'),
}
}
LANGUAGE_CODE = 'en-ZA'
LANGUAGE_COOKIE_AGE = None
LANGUAGE_COOKIE_NAME = 'django_language'
LANGUAGE_COOKIE_PATH = '/'
LOCALE_PATHS = (
os.path.join(BASE_DIR, '..', 'locale'),
)
TIME_ZONE = 'Africa/Johannesburg'
USE_I18N = True
USE_L10N = False
USE_TZ = True
MEDIA_ROOT = os.path.join(BASE_DIR, '..', 'media') + os.sep
MEDIA_URL = '/media/'
STATIC_ROOT = ''
STATIC_URL = '/static/'
STATICFILES_DIRS = (
os.path.join(BASE_DIR, '..', 'static'),
)
STATICFILES_FINDERS = (
'django.contrib.staticfiles.finders.FileSystemFinder',
'django.contrib.staticfiles.finders.AppDirectoriesFinder',
)
TEMPLATE_LOADERS = (
'django.template.loaders.filesystem.Loader',
'django.template.loaders.app_directories.Loader',
)
TEMPLATE_CONTEXT_PROCESSORS = (
"django.contrib.auth.context_processors.auth",
"django.core.context_processors.debug",
"django.core.context_processors.i18n",
"django.core.context_processors.media",
'django.template.context_processors.media',
"django.core.context_processors.static",
"django.core.context_processors.tz",
'django.core.context_processors.request',
"django.contrib.messages.context_processors.messages"
)
TEMPLATE_DIRS = (
os.path.join(BASE_DIR, '..', 'templates'),
)
SESSION_SERIALIZER = 'django.contrib.sessions.serializers.JSONSerializer'
LOGGING = {
'version': 1,
'disable_existing_loggers': False,
'filters': {
'require_debug_false': {
'()': 'django.utils.log.RequireDebugFalse'
}
},
'handlers': {
'mail_admins': {
'level': 'ERROR',
'filters': ['require_debug_false'],
'class': 'django.utils.log.AdminEmailHandler'
}
},
'loggers': {
'django.request': {
'handlers': ['mail_admins'],
'level': 'ERROR',
'propagate': True,
},
}
}
DEBUG_TOOLBAR_CONFIG = {
'INTERCEPT_REDIRECTS': False
}
INTERNAL_IPS = ('127.0.0.1', 'localhost')
MESSAGE_TAGS = {
message_constants.DEBUG: 'alert',
message_constants.INFO: 'alert alert-info',
message_constants.SUCCESS: 'alert alert-success',
message_constants.WARNING: 'alert alert-warning',
message_constants.ERROR: 'alert alert-danger'
}
if DEBUG: # Don't cache anything in debug
CACHES = {
'default': {
'BACKEND': 'django.core.cache.backends.dummy.DummyCache',
}
}
else:
CACHES = {
'default': {
'BACKEND': 'django.core.cache.backends.filebased.FileBasedCache',
'LOCATION': os.path.join(BASE_DIR, 'cache'),
}
}
答案 0 :(得分：2)
第78行的new_project/forms.py内部，您正在对表单模块的导入时间进行数据库查询。这不受支持，只有在应用程序完成初始化后才能进行任何数据库查询;通常，这意味着，在处理请求时。
在导入项目时无法进行数据库查询，因为需要首先导入它，以便Django可以执行数据库迁移，然后才能创建执行查询所需的数据库表。
更新：查看表单代码，您是否考虑使用ModelChoiceField而不是手动构建选项列表？
例如：
class ContactForm(forms.Form):
dealer = forms.ModelChoiceField(
queryset=Dealership.objects.all(),
label="Service Center",
required=True)
如果您想自定义Dealership的实例显示方式，您可以在the docs中找到相关说明。
答案 1 :(得分：0)
在加载python模块时执行ContactForm中的for循环，因此，在Django初始化之前执行它。相反，您可以在初始化时提供这些选择：
form ContactForm(forms.Form):
def __init__(self, *args, **kwargs):
super(ContactForm, self).__init__(*args, **kwargs)
dealerships = []
dealerships.append(("",("Select a dealer")))
all_dealerships = Dealership.objects.all()
for dealer in all_dealerships:
dealerships.append((dealer.name, _(dealer.name)))
self.fields['dealer'].choices = dealerships
dealer = forms.ChoiceField(
choices=[],
label="Service Center",
required=True)
但是，如文档所述：
请注意，选择可以是任何可迭代对象 - 不一定是列表或元组。这使您可以动态构造选择。 但是如果你发现你自己选择了动态的选择，你可能最好使用一个带有ForeignKey的正确数据库表。选择意味着静态数据不会发生太大变化，如果有的话。
来源：https://docs.djangoproject.com/en/1.9/ref/models/fields/#field-choices