django的多数据库的操作

1.项目目录

　　在存在两个app的时候使用两个数据

    

2.model类

app02/models.py

    在使用多数据库的时候,我们要到每个表的下面使用[app_label=app的名字],示例如下

class Publish(models.Model):
    name=models.CharField(max_length=32)
    email=models.EmailField()


    def __str__(self):
        return "app02 %s" % self.name

    class Meta:
　　　　#app的名字
        app_label = 'app02'

 3.settings的写法

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'orm',  ## 数据库名称
        'USER': 'root',
        'PASSWORD': '123456',  ## 安装 mysql 数据库时，输入的 root 用户的密码
        'HOST': '127.0.0.1',
    },
    'mysql02': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'orm02',  ## 数据库名称
        'USER': 'root',
        'PASSWORD': '123456',  ## 安装 mysql 数据库时，输入的 root 用户的密码
        'HOST': '127.0.0.1',
    },
}

# 多数据库连接池
DATABASE_ROUTERS = ['djangoser.database_router.DatabaseAppsRouter']
# 配置app与之相对应的连接池
DATABASE_APPS_MAPPING = {
    'app01': 'default',
    'app02': 'mysql02',

 4.在同级目录下添加database_router.py

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

    # for Django 1.4 - Django 1.6
    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

    # Django 1.7 - Django 1.11
    def allow_migrate(self, db, app_label, model_name=None, **hints):
        print(db, app_label, model_name, hints)
        if db in DATABASE_MAPPING.values():
            return DATABASE_MAPPING.get(app_label) == db
        elif app_label in DATABASE_MAPPING:
            return False
        return None

 5.执行命令

python manage.py makemigrations
--database指定要加载那个modles
python manage.py migrate --database=app02
#这样生成的数据库前缀app02_xxx