"""
Database
https://docs.djangoproject.com/en/1.11/ref/settings/#databases
"""
import pymysql
from django.db.models import options

pymysql.install_as_MySQLdb()

# 同一App下的Model可能会存储到不同的db，所以根据app_label来做db_router不是特别合适
# 所以添加situ_db_label来映射model到db
# 为Django的model的Meta添加额外的属性situ_db_label
options.DEFAULT_NAMES = tuple(list(options.DEFAULT_NAMES) + ['situ_db_label'])

# 数据库连接池配置
MYSQLPOOL_ARGUMENTS = {
    'recycle': 30,
    'pool_size': 64,
    'max_overflow': 10,
    'timeout': 5,
    'use_threadlocal': False,
}


class DBRouter(object):

    def db_for_read(self, model, **hints):
        if hasattr(model._meta, 'situ_db_label'):
            return model._meta.situ_db_label
        return None

    def db_for_write(self, model, **hints):
        if hasattr(model._meta, 'situ_db_label'):
            return model._meta.situ_db_label
        return None

    def allow_relation(self, obj1, obj2, **hints):
        return True