Question

我正在尝试在django上对我的数据库进行分片，但是我在第一步时遇到了奇怪的错误。

我制作了一个简单的数据库路由器，没有任何东西：

'''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中添加了：

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

我收到了这个错误：

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'连接'？这是什么意思？找不到，问题出在哪里（（

Answer 1

您需要在connections中导入settings.py：

from django.db import connections

...
...

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

Answer 2

你应该看看这个问题： Django multi-database routing

BTW，如the documentation中所述，allow_relation和allow_syncdb应返回True，False或None，不< / strong>数据库名称。

Answer 3

我的应用名称是与数据库alais user1同步的博客：

DATABASE_ROUTERS=['routers.BlogRouter']


DATABASES = {

    'default': {

        'ENGINE': 'django.db.backends.mysql', # Add 'postgresql_psycopg2', 'postgresql', 'mysql', 'sqlite3' or 'oracle'.


        'NAME': 'mupltiple_datab_app1',                      # Or path to database file if using sqlite3.

        'USER': 'root',                      # Not used with sqlite3.

        'PASSWORD': 'admin',                  # Not used with sqlite3.

        'HOST': "",                      # Set to empty string for localhost. Not used with sqlite3.

        'PORT': "",                      # Set to empty string for default. Not used with sqlite3.
    },
    'user1':{
        'ENGINE': 'django.db.backends.mysql', # Add 'postgresql_psycopg2', 'postgresql', 'mysql', 'sqlite3' or 'oracle'.

        'NAME': 'mupltiple_datab_app2',                      # Or path to database file if using sqlite3.

        'USER': 'root',                      # Not used with sqlite3.

        'PASSWORD': 'admin',                  # Not used with sqlite3.

        'HOST': "",                        # Set to empty string for localhost. Not used with sqlite3.

        'PORT': "",  


             }

    ,
    'user2':{
             'ENGINE': 'django.db.backends.mysql', # Add 'postgresql_psycopg2', 'postgresql', 'mysql', 'sqlite3' or 'oracle'.

        'NAME': 'mupltiple_datab_app3',                      # Or path to database file if using sqlite3.

        'USER': 'root',                      # Not used with sqlite3.

        'PASSWORD': 'admin',                  # Not used with sqlite3.

        'HOST':"" ,                      # Set to empty string for localhost. Not used with sqlite3.

        'PORT': "" ,  

             }
}

我确信在Django中使用多个数据库有一些未经探索的细微差别，我承认我还没有深入研究这个功能的底层代码，但是暂时一切似乎都按照要求工作。真正令人印象深刻的部分是在管理员中看到这两个应用没有错误。

django 1.4数据库路由器 - “无法导入名称连接”

3 个答案: