django 1.4 数据库路由器 - "cannot import name connection"

Question

我正在尝试在 django 上对我的数据库进行分片，但是在第一步中出现了奇怪的错误。

我做了一个简单的数据库路由器，什么都没有:

'''file /myproject/myapp/routers.py'''
class ShardingRouter(object):

    def db_for_read(self, model, **hints):
        return 'default'

    def db_for_write(self, model, **hints):
        return 'default'

    def allow_relation(self, obj1, obj2, **hints):
        return 'default'

    def allow_syncdb(self, db, model):
        return 'default'

我在settings.py中添加:

DATABASE_ROUTERS = ['myproject.myapp.routers.ShardingRouter',]

我收到此错误:

Traceback (most recent call last):
    File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/wsgi.py", line 219, in __call__
    self.load_middleware()
    File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py", line 45, in load_middleware
    mod = import_module(mw_module)
    File "/usr/local/lib/python2.7/dist-packages/django/utils/importlib.py", line 35, in import_module
    __import__(name)
    File "/hosting/myproject/myproject/middleware.py", line 10, in <module>
    from django.contrib.sites.models import Site
    File "/usr/local/lib/python2.7/dist-packages/django/contrib/sites/models.py", line 1, in <module>
    from django.db import models
    File "/usr/local/lib/python2.7/dist-packages/django/db/__init__.py", line 16, in <module>
    router = ConnectionRouter(settings.DATABASE_ROUTERS)
    File "/usr/local/lib/python2.7/dist-packages/django/db/utils.py", line 116, in __init__
    raise ImproperlyConfigured('Error importing database router %s: "%s"' % (klass_name, e))
ImproperlyConfigured: Error importing database router ShardingRouter: "cannot import name connection"

什么“联系”？这是什么意思？
找不到，问题出在哪里((

Answer 1

您需要导入 connections在您的 settings.py :

from django.db import connections

...
...

DATABASE_ROUTERS = ['myproject.myapp.routers.ShardingRouter',]
...
...