python bson.errors.InvalidDocument：无法编码对象：datetime.date(2015, 3, 1)

Question

我有以下功能：

#  this is in a module called 'dbw_lib'
def dateTimeOuput(start_days_back, end_days_back):
    start_delta = datetime.timedelta(days=start_days_back)
    end_delta = datetime.timedelta(days=end_days_back)
    start_date = datetime.date.today() - start_delta
    end_date = datetime.date.today() - end_delta
    return start_date, end_date

def dictByDate(start_days, end_days):
    start_date, end_date = dbw_lib.dateTimeOuput(start_days, end_days)

    date_string = { "created_at": {"$gte" : start_date, "$lt": end_date }  }

    user_id_email_dict = dbw_lib.dbwIdToEmailD(user_coll_obj, date_query = date_string)  # dict of all user ids and emails  
    print user_id_email_dict
    quit()

当我运行 key_dicts = dictByDate(90, 60) 时，我得到以下回溯：

Traceback (most recent call last):
File "main.py", line 212, in <module>
program.runProgram()
File "main.py", line 61, in runProgram
report.RcreateReport()
File "filepath/report.py", line 86, in RcreateReport
key_dicts = dictByDate(90, 60)
File "filepath/report.py", line 65, in dictByDate
user_id_email_dict = dbw_lib.dbwIdToEmailD(user_coll_obj, date_query = date_string)  # dict of all user ids and emails  
File "filepath/dbw_lib.py", line 50, in dbwIdToEmailD
for pair in id_email_cursor:
File "/Library/Python/2.7/site-packages/pymongo-3.0-py2.7-macosx-10.9-intel.egg/pymongo/cursor.py", line 968, in __next__
File "/Library/Python/2.7/site-packages/pymongo-3.0-py2.7-macosx-10.9-intel.egg/pymongo/cursor.py", line 905, in _refresh
File "/Library/Python/2.7/site-packages/pymongo-3.0-py2.7-macosx-10.9-intel.egg/pymongo/cursor.py", line 812, in __send_message
File "/Library/Python/2.7/site-packages/pymongo-3.0-py2.7-macosx-10.9-intel.egg/pymongo/mongo_client.py", line 732, in _send_message_with_response
File "/Library/Python/2.7/site-packages/pymongo-3.0-py2.7-macosx-10.9-intel.egg/pymongo/mongo_client.py", line 743, in _reset_on_error
File "/Library/Python/2.7/site-packages/pymongo-3.0-py2.7-macosx-10.9-intel.egg/pymongo/server.py", line 85, in send_message_with_response
File "/Library/Python/2.7/site-packages/pymongo-3.0-py2.7-macosx-10.9-intel.egg/pymongo/message.py", line 107, in get_message
bson.errors.InvalidDocument: Cannot encode object: datetime.date(2015, 3, 1)

Answer 1

datetime.date 不是 bson 编码器的一部分。（也许作者忘记了它或故意将其遗漏，因为像那样将时间信息附加到日期是模棱两可的。）

但是你可以在 pymongo 中编写一个函数来扩展自定义类型就像在 json 中扩展 JSONEncoder 一样，您可以在 pymongo 中使用 SONManipulator:

做类似的事情

import datetime
import pymongo

class MigrationTransformer(pymongo.son_manipulator.SONManipulator):

    def _encode_date(self, value):
        return datetime.datetime.combine(
                value,
                datetime.datetime.min.time())

    def transform_incoming(self, son, collection):
        for (key, value) in son.items():
            # datetime.datetime is instance of datetime.date
            # compare type explicitly only
            if type(value) == datetime.date:
                son[key] = self._encode_date(value)
            elif isinstance(value, dict):    # recurse into sub-docs
                son[key] = self.transform_incoming(value, collection)
        return son

然后将其附加到您的数据库实例：

db.add_son_manipulator(MigrationTransformer())

（我没有给出 transform_outgoing 方法，因为这与问题无关，但你可以在这里找到它：http://api.mongodb.org/python/current/examples/custom_type.html）

Edit: dict中的key的值是list类型会有问题。出于某种原因，pymongo 没有将它传递给 SONManipulator。所以列表没有转换。

我已经更新了 class 来处理这个问题（但我没有为 sets 和 tuples 做）。

class MigrationTransformer(SONManipulator):

    def _encode_date(self, value):
        return datetime.datetime.combine(
                value,
                datetime.datetime.min.time())

    def _handle_list(self, value):
        for index, item in enumerate(value):
            if isinstance(item, dict):
                value[index] = self._handle_dict(item)
            elif isinstance(item, list):
                value[index] = self._handle_list(item)
            elif isinstance(item, datetime.date):
                value[index] = self._encode_date(item)
        return value

    def _handle_dict(self, item):
        for (key, value) in item.items():
            if type(value) == datetime.date:
                item[key] = self._encode_date(value)
            elif isinstance(value, dict):    # recurse into sub-docs
                item[key] = self._handle_dict(value)
            elif isinstance(value, list):    # recurse into sub-docs
                item[key] = self._handle_list(value)
        return item

    def transform_incoming(self, son, collection):
        for (key, value) in son.items():
            # datetime.datetime is instance of datetime.date
            # compare type explicitly only
            if type(value) == datetime.date:
                son[key] = self._encode_date(value)
            elif isinstance(value, dict):    # recurse into sub-docs
                son[key] = self.transform_incoming(value, collection)
            elif isinstance(value, list):    # recurse into sub-docs
                son[key] = self._handle_list(value)
        return son

Answer 2

只是替换

datetime.date.today()

和

datetime.datetime.today()

但注意前者有日期，后者有 return 日期时间

Answer 3

结果是

PyMongo doesn't support saving date instances. The server doesn't have a type for dates without times, so there would have to be some convention used to save dates without times. If you need to save a date your client should convert it to a datetime instance and you can save that.

Quote's source.

This answer 声明这可以通过 datetime.datetime.combine 方法完成，如下所示：

datetime.datetime.combine(dateWithoutTime, datetime.time.min)

python bson.errors.InvalidDocument：无法编码对象：datetime.date(2015, 3, 1)

python bson.errors.InvalidDocument: Cannot encode object: datetime.date(2015, 3, 1)

python

datetime

pymongo

python-2.7