django多数据库的实现

参考文档：

* https://docs.djangoproject.com/en/1.2/topics/db/multi-db/#topics-db-multi-db-routing

* http://blog.sina.com.cn/s/blog_3fbe78a60100p68a.html

目的：新项目中实现按app实现数据库的分离

以非IC模块product为例

1. setting.py中加入

...
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql', # Add 'postgresql_psycopg2', 'postgresql', 'mysql', 'sqlite3' or 'oracle'.
        'NAME': 'xiaofei_ecgoo',                      # Or path to database file if using sqlite3.
        'USER': 'xiaofei',                      # Not used with sqlite3.
        'PASSWORD': '＊＊＊＊＊',                  # Not used with sqlite3.
        'HOST': '192.168.0.8',                      # Set to empty string for localhost. Not used with sqlite3.
        'PORT': '3306',                      # Set to empty string for default. Not used with sqlite3.
    },
     'product': {
        'ENGINE': 'django.db.backends.mysql', # Add 'postgresql_psycopg2', 'postgresql', 'mysql', 'sqlite3' or 'oracle'.
        'NAME': 'xiaofei_product',                      # Or path to database file if using sqlite3.
        'USER': 'xiaofei',                      # Not used with sqlite3.
        'PASSWORD': '*******',                  # Not used with sqlite3.
        'HOST': '192.168.0.8',                      # Set to empty string for localhost. Not used with sqlite3.
        'PORT': '3306',                      # Set to empty string for default. Not used with sqlite3.
    }
 }
...

2.增加dbrouter.py

class MyAppRouter(object):
    """A router to control all database operations on models in
    the myapp application"""

    def db_for_read(self, model, **hints):
        "Point all operations on myapp models to 'other'"
        if model._meta.app_label == 'product':
            return 'product'
        return None

    def db_for_write(self, model, **hints):
        "Point all operations on myapp models to 'other'"
        if model._meta.app_label == 'product':
            return 'product'
        return None

    def allow_relation(self, obj1, obj2, **hints):
        "Allow any relation if a model in myapp is involved"
        if obj1._meta.app_label == 'product' or obj2._meta.app_label == 'product':
            return True
        return None

    def allow_syncdb(self, db, model):
        "Make sure the myapp app only appears on the 'other' db"
        if db == 'product':
            return model._meta.app_label == 'product'
        elif model._meta.app_label == 'product':
            return False
        return None

class MasterSlaveRouter(object):
    """A router that sets up a simple master/slave configuration"""

    def db_for_read(self, model, **hints):
        "Point all read operations to a random slave"
        return 'default'

    def db_for_write(self, model, **hints):
        "Point all write operations to the master"
        return 'default'

    def allow_relation(self, obj1, obj2, **hints):
        "Allow any relation between two objects in the db pool"
        db_list = ('default','product')
        if obj1._state.db in db_list and obj2._state.db in db_list:
            return True
        return None

    def allow_syncdb(self, db, model):
        "Explicitly put all models on all databases."
        return True

3.配置settings.py

DATABASE_ROUTERS = ['new_ecgoo.dbrouter.MyAppRouter', 'new_ecgoo.dbrouter.MasterSlaveRouter']

注意：

写道

刚调试时，有几个页面一直报错，后发现数据库分离后，在读关联数据时，有几个写法要注意：
如：
ic = Ic.objects.filter(u__username=name)
应改为：
user = User.objects.get(username = name)
ic = Ic.objects.filter(u=user)

django多数据库的实现

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