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I am trying to write a string + datetime to a text file with Python. I'm trying to make a basic logger, that will log the datetime in a format of; "Full weekday, day number, Full month name, full year, 12 hour format, minute, second, AM/PM, UTC". I read that file.write() can only take strings and not integers or dates etc. So how would I would I make this work to be written to the text file?

grab_date = datetime.datetime.now().strftime("%A %d, %B %Y %I:%M:%S %p %Z")
firstline = "Log Created: ", grab_date, "/nLog deleted and recreated."
f = open("gen-log.txt", "w")
f.seek(0)
f.write(firstline)
f.close()

EDIT: not quite sure why but I read on one post that f.seek(0) did something and it worked for them. lol. I just left it in there. Sorry.

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  • What you're doing with fileline = foo, bar, baz is setting fileline to a tuple of three values. You can't write a tuple, only a string. (The fact that print can take a bunch of comma-separated arguments is because print is a special statement.) Commented Jul 28, 2014 at 19:08
  • why are you opening and then using seek? Commented Jul 28, 2014 at 19:09
  • Is there a reason you're trying to write your own logger instead of using the logging module? There are a whole lot of other things to deal with that you haven't even begun to approach (like appending instead of overwriting and/or moving the old file out of the way, and wrapping things up in a single function call so you don't have to write 6 lines of code for each log message, and deciding whether to keep the file open or reopen/close with each message or batch them up, and so on). Commented Jul 28, 2014 at 19:12
  • @abarnet just because you see only 6 lines of code doesnt mean thats all thats there. I have it in a function, and a bunch of other code. I just took the snippet that wasn't working. Python isnt the first programming language I know. Dont judge a book by its cover yo but thanks for the tip Commented Jul 28, 2014 at 19:17

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You can format your data into a string; with string formatting, for example:

firstline = "Log Created: {}/nLog deleted and recreated.".format(grab_date)

You can also make use of print()'s ability to convert all arguments to a string and automatic newlines, and have it write to the file:

print("Log Created:", grab_date, file=f)
print("Log deleted and recreated.", file=f)

If you can avoid it, don't reinvent the logging wheel and use the logging module. It can be configured to take a different date format:

>>> import logging
>>> logging.basicConfig(datefmt="%A %d, %B %Y %I:%M:%S %p %Z", format='Log Created: %(asctime)-15s %(message)s')
>>> logging.warn('Foo bar baz!')
Log Created: Monday 28, July 2014 08:13:44 PM BST Foo bar baz!
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2 Comments

Thanks for the help! Would it be worth using logging when all im really adding to the text file is just a few errors?
@catalyst: sure, logging is easy to use and gives you a lot of flexibility later when you may need more control. The module gives you that for free.

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