1. 构建DATABASES
2. 配置DATABASE_MAPPING，原理是因为DatabaseAppsRouter需要用到DATABASE_APPS_MAPPING = {'app1': 'db1', 'app2': 'db2'}

import copy
import datetime

from django.conf import settings


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


DEFAULT_DATABASES = {
    # 'ENGINE': 'django.db.backends.mysql',
    'ENGINE': 'dj_db_conn_pool.backends.mysql',
    'NAME': 'xxxxxxx',
    'HOST': '127.0.0.1',
    'USER': 'xxxxx',
    'PASSWORD': 'xxxxxx',
    'PORT': 3306,
    'CONN_MAX_AGE': 0,    # 默认： 0  一个数据库连接的寿命，以秒为整数。使用 0 在每次请求结束时关闭数据库连接——这是 Django 的历史行为，使用 None 则是无限的持久连接。
    'OPTIONS': {
        'charset': 'utf8mb4',
        'connect_timeout': 30,  # 连接超时时间
    },
    'POOL_OPTIONS': {   # dj_db_conn_pool的参数
        'POOL_SIZE': 1,
        'MAX_OVERFLOW': 11,
        'RECYCLE': 60,
    }
}


TIDB_DATABASE_JYCM = copy.deepcopy(DEFAULT_DATABASES)
TIDB_DATABASE_JYCM.update(dict(
    NAME='xxxx',
    HOST='xxxxx',
    USER='xxxxx',
    PASSWORD='xxxxxx',
    PORT=3307,
))

# if settings.DEBUG:
#     _DATABASE_DEFAULT.update({'HOST': '47.119.200.228', 'USER': 'suncent_test', 'PASSWORD': 'N&Gn397mMeE1t81D', })
#     warning, warning_major = '0;33', '0;36'
#     print(f"\033[{warning}m【{datetime.datetime.now()}】 WARNING 您目前所处的环境是\033[0m\033[{warning_major}mDEBUG\033[0m\033[{warning}m模式,所使用的数据库为测试库({_DATABASE_DEFAULT.get('HOST')}）\033[0m")


DATABASES = {
    'default': DEFAULT_DATABASES,
    'jycm': TIDB_DATABASE_JYCM,
}
DATABASE_MAPPING = {    # app-database映射
    'bgdata_jycm': 'jycm',
}
DATABASE_ROUTERS = ['bgdata_api.settings_database.DatabaseAppsRouter']

# DJORM_POOL_PESSIMISTIC = True
# DEBUG模式下打开这个可以查看sql语句
# LOGGING = {
#     'version': 1,
#     'disable_existing_loggers': False,
#     'handlers': {
#         'console':{
#             'level':'DEBUG',
#             'class':'logging.StreamHandler',
#         },
#     },
#     'loggers': {
#         'django.db.backends': {
#             'handlers': ['console'],
#             'propagate': True,
#             'level':'DEBUG',
#         },
#     }
# }