Python how to check different date formats for multiple string values

Question

I have a set of variables(epoch_time,normal_date,date_time,date_time_zone) which can be passed randomly and based on the string format, I am converting it into my required date format (%Y-%m-%d). My variable can be a string with epoch value or string with date timezone or string with datetime or only date. I have tried the following way and it is always going into the first item only in allowed_date_formats. Can someone suggest me a better approach or help me in resolving the issue.

from datetime import datetime
epoch_time='1481883402'
normal_date="2014-09-03"
date_time=str("2014-05-12 00:00:00")
date_time_zone=str("2015-01-20 08:28:16 UTC")
OP_FORMAT="%Y-%m-%d"
ALLOWED_STRING_FORMATS=["%Y-%m-%d %H:%M:%S %Z","%Y-%m-%d %H:%M:%S","%Y-%m-%d"]

def convert_timestamp(date_timestamp=None):
    for format in ALLOWED_STRING_FORMATS:
        if datetime.strptime(date_timestamp,format):
            d=datetime.strptime(date_timestamp,"%Y-%m-%d")
        else:
            d = datetime.fromtimestamp((float(date_timestamp) / 1000.), tz=None)
    return d.strftime(OP_FORMAT)

print(convert_timestamp(normal_date))

Error that i am getting is

ValueError: time data '2014-09-03' does not match format '%Y-%m-%d %H:%M:%S %Z'

If you want to avoid error(e.g. if format can't be used) you should use try and except above the if datetime.strptime(date_timestamp,format): and else:. — BladeMight
– BladeMight, Commented Oct 18, 2018 at 21:09

Håken Lid · Accepted Answer · 2018-10-18 21:28:58Z

5

You can use try-except for this.

def convert_timestamp(date_timestamp, output_format="%Y-%m-%d"):
    ALLOWED_STRING_FORMATS=[
        "%Y-%m-%d %H:%M:%S %Z",
        "%Y-%m-%d %H:%M:%S",
        "%Y-%m-%d",
    ]

    for format in ALLOWED_STRING_FORMATS:
        try: 
            d = datetime.strptime(date_timestamp,format):
            return d.strftime(output_format)
        except ValueError:
            pass
    try:
        # unix epoch timestamp
        epoch = int(date_timestamp) / 1000
        return datetime.fromtimestamp(epoch).strftime(output_format)
    except ValueError:
        raise ValueError('The timestamp did not match any of the allowed formats')

edited Oct 18, 2018 at 21:28

answered Oct 18, 2018 at 21:08

Håken Lid

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2 Comments

Auto-learner Over a year ago

my string contains epoch format as well, can u pls help with that condition also

Håken Lid Over a year ago

I've added epoch case at the end of the function. I initially thought python strptime might support the epoch %s format (lowercase s), but it doesn't. strftime, on the other hand, uses the platform C library, so it does support %s, at least on linux.

Felix · Accepted Answer · 2018-10-18 21:09:54Z

1

Do you need to make sure that only specific formats are allowed?

Otherwise you might consider using the automatic parser from dateutil:

from dateutil import parser
normal_date="2014-09-03"
print(parser.parse(normal_date))

answered Oct 18, 2018 at 21:09

Felix

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1 Comment

Auto-learner Over a year ago

Thanks for the answer but I would like to consider python default module only.

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