错题集（已解决）：pymongo报错InvalidDocument: Cannot encode object: 52（某个数值）

今天写个宏玩，结果发现一个可能是编码引发的问题··· 完全不知道怎么处理··

import pandas as pd
import numpy  as np
import pymongo
myclient = pymongo.MongoClient(host='mongodb://localhost:27017/')
mydbs    = myclient['db_WebCrwr']
mycll    = mydbs['ttt']

lst_test1 = [{'A':52}]
dtf_test1 = pd.DataFrame(lst_test1)
lst_test2 = dtf_test1[['A']].to_dict(orient='records')

print("lst_test1[0] = ",lst_test1[0])
print("lst_test2[0] = ",lst_test2[0],'\n')

print("type of lst_test1[0]: ",type(lst_test2[0]))
print("type of lst_test2[0]: ",type(lst_test2[0]),'\n')

print("result of lst_test1[0]: ",mycll.find_one(lst_test1[0]))
print("result of lst_test2[0]: ",mycll.find_one(lst_test2[0]))

即直接输入的列表lst_test1可以正常使用pymongo的find_one找到对应的mongodb库表中已经存在的document，但是转成数据框再转回列表lst_test2后就不能正常执行find_one了，报解码错误。
运行结果如下：

---

更新180912：

pandas将字典转数据框再转回来的时候，原来type = int的数值type = numpy.int64导致pymongo不能encode；解答参考：
https://segmentfault.com/q/1010000007300393/a-1020000012847675

---

具体的报错信息如下：

InvalidDocument                           Traceback (most recent call last)
 in ()
     26 
     27 print(mycll.find_one(lst_test1[0]))
---> 28 print(mycll.find_one(lst_test2[0]))

C:\ProgramData\Anaconda3\lib\site-packages\pymongo\collection.py in find_one(self, filter, *args, **kwargs)
   1260 
   1261         cursor = self.find(filter, *args, **kwargs)
-> 1262         for result in cursor.limit(-1):
   1263             return result
   1264         return None

C:\ProgramData\Anaconda3\lib\site-packages\pymongo\cursor.py in next(self)
   1187         if self.__empty:
   1188             raise StopIteration
-> 1189         if len(self.__data) or self._refresh():
   1190             if self.__manipulate:
   1191                 _db = self.__collection.database

C:\ProgramData\Anaconda3\lib\site-packages\pymongo\cursor.py in _refresh(self)
   1102                                   self.__session,
   1103                                   self.__collection.database.client)
-> 1104             self.__send_message(q)
   1105         elif self.__id:  # Get More
   1106             if self.__limit:

C:\ProgramData\Anaconda3\lib\site-packages\pymongo\cursor.py in __send_message(self, operation)
    929             try:
    930                 response = client._send_message_with_response(
--> 931                     operation, exhaust=self.__exhaust, address=self.__address)
    932                 self.__address = response.address
    933                 if self.__exhaust:

C:\ProgramData\Anaconda3\lib\site-packages\pymongo\mongo_client.py in _send_message_with_response(self, operation, exhaust, address)
   1143             self.__all_credentials,
   1144             self._event_listeners,
-> 1145             exhaust)
   1146 
   1147     def _reset_on_error(self, server, func, *args, **kwargs):

C:\ProgramData\Anaconda3\lib\site-packages\pymongo\mongo_client.py in _reset_on_error(self, server, func, *args, **kwargs)
   1154         """
   1155         try:
-> 1156             return func(*args, **kwargs)
   1157         except NetworkTimeout:
   1158             # The socket has been closed. Don't reset the server.

C:\ProgramData\Anaconda3\lib\site-packages\pymongo\server.py in send_message_with_response(self, operation, set_slave_okay, all_credentials, listeners, exhaust)
     92             use_find_cmd = operation.use_command(sock_info, exhaust)
     93             message = operation.get_message(
---> 94                 set_slave_okay, sock_info, use_find_cmd)
     95             request_id, data, max_doc_size = self._split_message(message)
     96 

C:\ProgramData\Anaconda3\lib\site-packages\pymongo\message.py in get_message(self, set_slave_ok, sock_info, use_cmd)
    320                     0, spec, self.db, self.read_preference,
    321                     set_slave_ok, False, self.codec_options,
--> 322                     ctx=sock_info.compression_context)
    323                 return request_id, msg, size
    324             ns = _UJOIN % (self.db, "$cmd")

C:\ProgramData\Anaconda3\lib\site-packages\pymongo\message.py in _op_msg(flags, command, dbname, read_preference, slave_ok, check_keys, opts, ctx)
    677                 flags, command, identifier, docs, check_keys, opts, ctx)
    678         return _op_msg_uncompressed(
--> 679             flags, command, identifier, docs, check_keys, opts)
    680     finally:
    681         # Add the field back to the command.

InvalidDocument: Cannot encode object: 52