正确地导入Django管理命令
正确地导入Django管理命令
自定义管理命令oauth.py需要从另一个模块中获取一个模型。当我包含"from appname.authentication.models import Contact"时，我得到"AttributeError: 'module' object has no attribute 'models'." - 在我能够构建一个测试套件来帮助升级之前，我被困在django 1.6上。
我应该如何正确地导入Contact？
其他值得注意的SO答案：
除/app目录外的每个目录都有一个__init__.py。/app在sys.path / django目录中，/app:
util -management --commands ---oauth.py appname -authentication --models.py extouth.py
extoauth.py是一个独立的脚本，具有相同的导入并且可以工作，但仅在manage.py shell中。自定义管理命令将更好。
oauth.py:
import sys
from optparse import make_option
from provider.oauth2.models import Client
from appname.authentication.models import Contact
from django.core.management.base import BaseCommand
class Command(BaseCommand):
help = '创建OAUTH用户并获取访问令牌。'
option_list = BaseCommand.option_list + (
make_option('--create-client',
dest='create_client',
help='''返回元组...'''),
make_option('--get-access-token',
dest='get_access_token',
help='''返回有时间限制的访问令牌...'''),
)
def handle(self, *args, **options):
if options['create_client']:
return self.create_client(options['create_client'])
elif options['get_access_token']:
self.get_access_token()
def create_client(self, user):
return user
def get_access_token(self):
pass
控制台输出：
Traceback (most recent call last): File "manage.py", line 10, inexecute_from_command_line(sys.argv) File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 399, in execute_from_command_line utility.execute() File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 392, in execute self.fetch_command(subcommand).run_from_argv(self.argv) File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 272, in fetch_command klass = load_command_class(app_name, subcommand) File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 75, in load_command_class module = import_module('%s.management.commands.%s' % (app_name, name)) File "/usr/local/lib/python2.7/site-packages/django/utils/importlib.py", line 40, in import_module __import__(name) File "/app/waapiutil/management/commands/oauth.py", line 4, in from wowza.authentication.models import Contact File "/app/wowza/authentication/models.py", line 80, in class SalesforceModel(with_metaclass(salesforce.models.SalesforceModelBase, models.Model)): AttributeError: 'module' object has no attribute 'models'
假设 - 设置未被导入
因此，我的设置必须像在manage.py shell使用时一样被设置，因为如果我在文件顶部包含：
from django.conf import settings
settings.configure()
我得到：
Traceback (most recent call last): File "manage.py", line 10, inexecute_from_command_line(sys.argv) File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 399, in execute_from_command_line utility.execute() File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 392, in execute self.fetch_command(subcommand).run_from_argv(self.argv) File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 272, in fetch_command klass = load_command_class(app_name, subcommand) File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 75, in load_command_class module = import_module('%s.management.commands.%s' % (app_name, name)) File "/usr/local/lib/python2.7/site-packages/django/utils/importlib.py", line 40, in import_module __import__(name) File "/app/waapiutil/management/commands/oauth.py", line 2, in settings.configure() File "/usr/local/lib/python2.7/site-packages/django/conf/__init__.py", line 89, in configure raise RuntimeError('Settings already configured.') RuntimeError: Settings already configured.
假设 - 更深的语法错误（这应该会破坏生产）
在我的应用程序文件中搜索models.model的出现次数会得到四个结果，每个都具有正确的models.Model的大小写。
假设 - Contact已经被导入
当我注释掉导入并运行命令时，我得到：
Traceback (most recent call last): File "manage.py", line 10, inexecute_from_command_line(sys.argv) File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 399, in execute_from_command_line utility.execute() File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 392, in execute self.fetch_command(subcommand).run_from_argv(self.argv) File "/usr/local/lib/python2.7/site-packages/django/core/management/base.py", line 242, in run_from_argv self.execute(*args, **options.__dict__) File "/usr/local/lib/python2.7/site-packages/django/core/management/base.py", line 285, in execute output = self.handle(*args, **options) File "/app/waapiutil/management/commands/oauth.py", line 23, in handle return self.create_client(options['create_client']) File "/app/waapiutil/management/commands/oauth.py", line 32, in create_client c = Client(user=Contact.objects.get_by_email(e), name=n, NameError: global name 'Contact' is not defined
authentication/models.py的片段，用于hynekcer的评论
# Core Django imports
from django.db import models
from django.core.validators import MinLengthValidator
from django.utils.six import with_metaclass
# Third-party imports
import pycountry
from rest_framework.compat import oauth2_provider
import salesforce
from salesforce import fields
from salesforce.backend import manager
...
class SalesforceManager(manager.SalesforceManager):
"""
重写默认的Salesforce管理器，以便我们可以获得一些合适的REST框架异常
"""
def get(self, *args, **kwargs):
try:
result = self.get_queryset().get(*args, **kwargs)
except self.model.MultipleObjectsReturned:
raise MultipleUniqueRecords()
except Exception as e:
logger.warning("SalesForce exception %s", str(e))
raise NoRecord()
return result
class SalesforceModel(with_metaclass(salesforce.models.SalesforceModelBase, models.Model)):
"""
Salesforce对象的抽象模型类。
"""
_base_manager = objects = SalesforceManager()
_salesforce_object = True
class Meta:
managed = False
abstract = True
Id = fields.SalesforceAutoField(primary_key=True)
def clean_fields(self, *args, **kwargs):
# 覆盖默认的clean_fields方法，以便我们可以捕获验证异常
try:
super(SalesforceModel, self).clean_fields(*args, **kwargs)
except Exception as validation_exception:
detail = ''
for field, message in validation_exception.error_dict.items():
detail += field + ': ' + message[0].messages[0]
raise ValidationError(detail)
def save(self, *args, **kwargs):
# 覆盖默认的save方法，以便我们可以删除Salesforce管理的字段
if self._meta.model_name in ['contact', 'account', 'license', 'sslcertificate']:
if not self.Id:
for field in self._meta.fields:
if field.attname == 'created_date' or field.attname == 'certificate_id':
self._meta.fields.remove(field)
else:
update_fields = self._meta.get_all_field_names()
remove_list = []
if self._meta.model_name == 'contact':
remove_list = ['created_date', 'accesstoken', 'refreshtoken', 'oauth2_client', 'grant', 'Id', 'entitlement_plan']
elif self._meta.model_name == 'account':
remove_list = ['created_date', 'account', 'Id']
elif self._meta.model_name == 'license':
remove_list = ['created_date', 'Id']
elif self._meta.model_name == 'sslcertificate':
remove_list = ['certificate_id', 'created_date', 'Id']
for remove_field in remove_list:
if remove_field in update_fields:
update_fields.remove(remove_field)
kwargs['update_fields'] = update_fields
# 如果出现SalesforceError，则重试五次
delay = 1
for retry in range(5):
try:
super(SalesforceModel, self).save(*args, **kwargs)
break
except Exception as e:
logger.error("Saving {0} resulted in an error {1}, retry {2}".format(str(self),str(e),retry))
if retry < 4 and "SERVER_UNAVAILABLE" in str(e):
time.sleep(delay)
delay *= 2
else:
问题原因：在Django管理命令中正确导入的问题出现的原因是，代码中存在对于旧版本django-salesforce的依赖，而没有适应当前版本的更新。
解决方法：使用公共API是最安全的方式。更脆弱的方式是使用未记录的功能。最脆弱的方式是复制其他包的核心代码，并忘记你开始使用了新版本。如果你这样做，你必须有足够严重的原因和足够的时间。你可以简单地编写以下代码：
class MySalesforceModel(salesforce.models.SalesforceModel):
def ... # your custom method
class Meta:
managed = False
abstract = True
这样做的优势是，即使在下一个版本的Django和django-salesforce中，它也会使用正确的当前SalesforceModel。
如果你真的需要自定义后端，请合理地将后端和应用程序代码分离到不同的模块中，以便可以在不导入任何具体模型的情况下导入后端。否则，你可能会出现丑陋的依赖关系。同时，一个非空的`__init__.py`可能会导致愚蠢的依赖关系。
当你拥有完整的源代码时，对于这些简单的问题，你无需进行假设。你可以简单地记录（打印）这些信息，例如使用以下代码：
import sys; print("settings imported", "my_project.settings" in sys.modules)
或者验证设置是否正确配置-在有问题的位置之前暂时加上一行代码：
from django.conf import settings; print(settings.INSTALLED_APPS) # any valid name
在寻求帮助之前，你应该检查语法错误。可以通过以下方式轻松地为Python特定版本的子目录树进行编译：
python2.7 -m compileall $(pwd)
尤其是在调试时，使用通用的`except Exception:`是非常疯狂的。想象一下，如果在try...except之间的代码引发了一个ImportError并且你却将其吞下。解决依赖关系可能比后期维护脆弱的代码更容易。想象一下，如果你在一个函数内部导入并且只有在Apache中从一个线程导入模块时，你的朋友才会收到奇怪的ImportError消息，但如果你从主线程导入它则成功。显式导入是首选。