django 多数据库配置

修改项目的 settings 配置 

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'sqlite3'),
    },
    'db01': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db_01'),
    },
    'db02': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db_02'),
    },
}

DATABASE_ROUTERS = ['Prject_name.database_router.DatabaseAppsRouter']  

# Project: 建立的django项目名称(project_name)
# database_router: 定义路由规则database_router.py 文件名称, 这个文件名可以自己定义
# DatabaseAppsRouter: 路由规则的类名称，这个类是在database_router.py 文件中定义

 

DATABASE_APPS_MAPPING = {

# 设置APP对应的数据库路由表 ，如果不指定则会自动创建到默认（default）的数据库中
# example:
# 'app_name':'database_name',
'app02': 'db02',
'app01': 'db01',
'admin': 'db01',
'auth': 'db01',
'contenttypes': 'db01',
'sessions': 'db01',
}

 

创建数据库路由规则 

创建 database_router.py 文件，与 settings.py 文件同级

from django.conf import settings

DATABASE_MAPPING = settings.DATABASE_APPS_MAPPING


class DatabaseAppsRouter(object):
    """
    A router to control all database operations on models for different
    databases.

    In case an app is not set in settings.DATABASE_APPS_MAPPING, the router
    will fallback to the `default` database.

    Settings example:

    DATABASE_APPS_MAPPING = {'app1': 'db1', 'app2': 'db2'}
    """

    def db_for_read(self, model, **hints):
        """"Point all read operations to the specific database."""
        if model._meta.app_label in DATABASE_MAPPING:
            return DATABASE_MAPPING[model._meta.app_label]
        return None

    def db_for_write(self, model, **hints):
        """Point all write operations to the specific database."""
        if model._meta.app_label in DATABASE_MAPPING:
            return DATABASE_MAPPING[model._meta.app_label]
        return None

    def allow_relation(self, obj1, obj2, **hints):
        """Allow any relation between apps that use the same database."""
        db_obj1 = DATABASE_MAPPING.get(obj1._meta.app_label)
        db_obj2 = DATABASE_MAPPING.get(obj2._meta.app_label)
        if db_obj1 and db_obj2:
            if db_obj1 == db_obj2:
                return True
            else:
                return False
        return None

    def allow_syncdb(self, db, model):
        """Make sure that apps only appear in the related database."""

        if db in DATABASE_MAPPING.values():
            return DATABASE_MAPPING.get(model._meta.app_label) == db
        elif model._meta.app_label in DATABASE_MAPPING:
            return False
        return None

    def allow_migrate(self, db, app_label, model=None, **hints):
        """
        Make sure the auth app only appears in the 'auth_db'
        database.
        """
        if db in DATABASE_MAPPING.values():
            return DATABASE_MAPPING.get(app_label) == db
        elif app_label in DATABASE_MAPPING:
            return False
        return None

 

各自的 APP 中创建数据表的models时，必须要指定表的 app_label 名字，如果不指定则会创建到 default 中配置的数据库名下

class Users(models.Model):
    name = models.CharField(max_length=50)
    passwd = models.CharField(max_length=100)

    def __str__(self):
        return "app01 %s " % self.name

    class Meta:
        app_label = "app01"

 

生成数据表 

在使用django的 migrate 创建生成表的时候，需要加上 –database 参数，如果不加则将 未 指定 app_label 的 APP的models中的表创建到default指定的数据库中,如:

python manage.py  migrate  --database=db01    

以上创建完成后,其它所有的创建、查询、删除等操作就和普通一样操作就可以了,无需再使用类似 
models.User.objects.using(dbname).all(）