I have a JSON file that has dates and integers in them. All of them are showing as strings. I used a JSON decoder to get the strings parsed into integers, but I am having issues getting the date strings into actual date format. My JSON file is below:

{"Time Open": "71", "Name": "John Doe", "Date Closed": "", "Date Created": "4/11/2021", "Due Date": "5/29/2021", "TimeStamp": "08/09/2021 00:00:00 AM"}

So far I used the "isinstance" to parse the Time Open strings into integers, but the "isinstance" isn't working for changing the dates "4/11/2021" to "2021-04-11" Seems like its not detecting my datetime.datetime "isinstance". Any help will be appreciated. I have my code below.

from datetime import datetime

class Decoder(json.JSONDecoder):
    def decode(self, s):
        result = super().decode(s)  # result = super(Decoder, self).decode(s) for Python 2.x
        return self._decode(result)
    
    def _decode(self, o):
        if isinstance(o, str):
            try:
                return int(o)
            except ValueError:
                return o
        elif isinstance(o, datetime):
            try:
                return datetime.datetime.strptime(o, "%m/%d/%Y").strftime("%Y-%m-%d")
            except ValueError:
                return o
        elif isinstance(o, dict):
            return {k: self._decode(v) for k, v in o.items()}
        elif isinstance(o, list):
            return [self._decode(v) for v in o]
        else:
            return o 

I'm using json.loads to go to this Decoder class as below:

json_doc = json.loads(doc, cls=Decoder)