[Python知识库]Django-数据库路由映射

1.在项目根目录下新建文件夹settings（名字随意），然后在文件夹下新建router.py文件，添加代码如下（代码不用修改）

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

2.在项目的settings.py文件中增加对应数据库配置

3.在项目的settings.py文件中引入数据库路由配置，settings.router.DatabaseAppsRouter为第一步创建的类的路径

DATABASE_ROUTERS = ['settings.router.DatabaseAppsRouter']

4.在项目的settings.py文件中增加数据库与APP的映射配置，支持每个APP都使用不同的数据库

格式为： 'app名称': '数据库名称',

DATABASE_APPS_MAPPING = {
    'app01': 'default',
    'app02': 'mtisp',
????'app03': 'mtisp', 
}

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