In Python: check if file modification time is older than a specific datetime

Question

I wrote this code in c# to check if a file is out of date:

 DateTime? lastTimeModified = file.getLastTimeModified();
        if (!lastTimeModified.HasValue)
        {
            //File does not exist, so it is out of date
            return true;
        }
        if (lastTimeModified.Value < DateTime.Now.AddMinutes(-synchIntervall))
        {
            return true;
        } else
        {
           return false;
        }

How do I write this in python?

I tried this in python.

statbuf = os.stat(filename)
if(statbuf.st_mtime < datetime.datetime.now() - self.synchIntervall):
    return True
 else:
    return False

I got the following exception

message str: unsupported operand type(s) for -: 'datetime.datetime' and 'int'   

Answer 1

Here is a generic solution using timedelta

from datetime import datetime

def is_file_older_than (file, delta): 
    cutoff = datetime.utcnow() - delta
    mtime = datetime.utcfromtimestamp(os.path.getmtime(file))
    if mtime < cutoff:
        return True
    return False

This can be used as follows.

To detect a file older than 10 seconds:

from datetime import timedelta

is_file_older_than(filename, timedelta(seconds=10))

To detect a file older than 10 days:

from datetime import timedelta

is_file_older_than(filename, timedelta(days=10))

If you are ok installing external dependencies, you can also do months and years:

from dateutil.relativedelta import relativedelta # pip install python-dateutil

is_file_older_than(filename, relativedelta(months=10))