How do I parse a Microsoft JSON date in Python?

Question

I have to read a JSON file and It has the date fields formated like this below

"MyDate": "/Date(1603284014088)/",

I found some examples to parse it in other languages (JavaScript, Kotlin) but nothing in Python.

I could find on this SCOTT HANSELMAN's post here that they are milliseconds since the beginning of the Unix Epoch sometimes with a TimeZone. So I could write a simple function to decode it.

import re
from datetime import datetime, timedelta

def decode_date (encoded_date):
    mask = "\/Date\(([0-9]*)\)"
    offset = datetime(1970, 1, 1)
    my_matchs = re.match(mask, encoded_date).groups()
    if len(my_matchs) == 1:
        return datetime(1970, 1, 1) + timedelta(milliseconds=int(my_matchs[0]))
    else:
        return None
    

encoded = "/Date(1603284014088)/"
print (decode_date(encoded))

This function can't parse dates with timezone because I'm lazy :), My question is - is there some lib that can parse it out of the box in Python?

You don't - you tell whoever created that service that eve ASP.NET Web API uses ISO8601 for dates. Nobody uses that Unix timestamp for almost 10 years — Panagiotis Kanavos
– Panagiotis Kanavos, Commented Oct 23, 2020 at 14:45
You can use datetime.fromtimestamp to convert the Unix timestamp value directly, there's no need to do it yourself — Panagiotis Kanavos
– Panagiotis Kanavos, Commented Oct 23, 2020 at 14:50
@PanagiotisKanavos I could live with milliseconds-since-the-epoch being returned. What really isn't necessary is the /Date(...) wrapper around it. — chepner
– chepner, Commented Oct 23, 2020 at 15:00
I edited my code to deal with not match strings.. I absolutellly agree with Panagiotis Kanavos but it was a ended project already validated I can ask that guy to change it now. — Alex
– Alex, Commented Oct 23, 2020 at 15:04
Hello, did you have a moment to check my reply? If it was useful for you please consider upvoting it and / or choosing it as final answer. Thanks for your time! — Pitto
– Pitto, Commented Mar 26, 2021 at 9:20

Pitto · Accepted Answer · 2020-10-23 14:49:12Z

1

Given the fact that you are already able to extract the date using RegEx please try the following code for conversion:

import datetime

s = '1603284014088'
fmt = "%Y-%m-%d %H:%M:%S"

# Local time
t = datetime.datetime.fromtimestamp(float(s)/1000.)
print (t.strftime(fmt))

# UTC time
t_utc = datetime.datetime.utcfromtimestamp(float(s)/1000.)
print (t_utc.strftime(fmt))

answered Oct 23, 2020 at 14:49

Pitto

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4 Comments

chepner Over a year ago

The call to float isn't necessary. Dividing by a float will produce a float result. In Python 3, / will always produce a float, even if both arguments are ints, so s/1000 is sufficient.

pho Over a year ago

@chepner s is a string so you need the call to float.

chepner Over a year ago

Oh, sorry, got ahead of myself. I assumed s was already an int.

chepner Over a year ago

But that said, int(s)/1000 would be sufficient and "stricter", as it is expected that s is the string representation of an int.

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