sqlalchemy结果转json

网上搜了下，http://blog.csdn.net/liu_xing_hui/article/details/8956107
介绍的很详细，自动一个Encoder给json的dump方法使用，能够实现queryresult转json

import json
from sqlalchemy.ext.declarative import DeclarativeMeta
from datetime import datetime

def new_alchemy_encoder():
    _visited_objs = []

    class AlchemyEncoder(json.JSONEncoder):
        def default(self, obj):
            if isinstance(obj.__class__, DeclarativeMeta):
                # don't re-visit self
                if obj in _visited_objs:
                    return None
                _visited_objs.append(obj)

                # an SQLAlchemy class
                fields = {}
                for field in [x for x in dir(obj) if not x.startswith('_') and x != 'metadata']:
                    data = obj.__getattribute__(field)
                    try:
                        if isinstance(data, datetime):
                            data = data.strftime('%Y-%m-%d %H:%M:%S')
                        json.dumps(data)  # this will fail on non-encodable values, like other classes
                        fields[field] = data
                    except TypeError:
                        fields[field] = None
                return fields

            return json.JSONEncoder.default(self, obj)
    return AlchemyEncoder

UnReadMsg = self.db.query(Message).filter(Message.uid == self.uid)
msgs = []
for msg in UnReadMsg:
    msgs.append(msg)
UnReadMsg = json.dumps(msgs, cls=new_alchemy_encoder(), check_circular=False)

但是新版的sqlalchemy中的queryresult对象加入了json属性，直接能得到json串，棒棒哒

UnReadMsg = self.db.query(Message).filter(Message.uid == self.uid)
msgs = []
for msg in UnReadMsg:
    msgs.append(msg.json)
print(msgs)
return JsonResponse(self, 50000, data=msgs)   

直接拿到结果爽的不要不要的，不过还是要知道这个dump方式是怎么实现的，这样以后也能处理更复杂的情况

{
  "code": 50000,
  "data": [
    {
      "content": "你好啊",
      "entry_date": "2017-2-20 20:40",
      "msg_id": "2",
      "msg_readstatus": "1",
      "msg_sendstatus": "1",
      "msg_type": "1",
      "read_time": "",
      "send_time": "2017-2-20 20:40",
      "stamped": "0",
      "suid": "3",
      "uid": "1"
    },
    {
      "content": "好的很",
      "entry_date": "2017-2-20 20:41",
      "msg_id": "3",
      "msg_readstatus": "1",
      "msg_sendstatus": "1",
      "msg_type": "1",
      "read_time": "",
      "send_time": "2017-2-20 20:41",
      "stamped": "0",
      "suid": "2",
      "uid": "1"
    }
  ],
  "msg": null
}