Is there a more elegant way to handle empty values in this scraper?

Question

Now that I've figured out How do I strtotime in python? I'm wondering if there's a more elegant way to handle entries with empty dates, which return an error if I try to strptime() them.

warrant_issued = cells[4].get_text().strip()
try:
    warrant_issued_no = datetime.strptime(warrant_issued, '%m/%d/%Y')
except:
    warrant_issued_no = ''

This works, but I'm parsing four or five dates in each row and it seems both wordy and repetitive. I'm thinking I should define a function, but are there other ways I should make this more pythonic?

For brevity, I did from datetime import datetime at the outset so datetime.strptime() works. Otherwise I'd need datetime.datetime.strptime()

Answer 1

I think that defining a function and catching only exceptions that you know how to handle is precisely the way to do this.

def parse_datetime(warrant_issued):
   try:
      warrant_issued_no = datetime.strptime(warrant_issued, '%m/%d/%Y')
   except ValueError:
      warrant_issued_no = ''

warrants_issued = [ parse_datetime(cell.get_text().strip()) for cell in cells ]

Answer 2

I think you might be slightly better off doing something similiar to what @mgilson said, but with an if statement rather than try/catch, since you may accidentally catch errors you didn't mean to.

My understanding is that the error you're looking to catch here is when the date field is blank, so that's what I'm going with.

def parse_datetime(warrant_issued):
    # Using Python's "truthiness" to take care of both '' and None, however it comes out
    if warrant_issued:
        warrant_issued_no = datetime.strptime(warrant_issued, '%m/%d/%Y')
    else:
        warrant_issued_no = ''

warrants_issued = [parse_datetime(cell.get_text().strip()) for cell in cells]

This way, if you end up getting some other error that still throws a ValueError but isn't from there not being a date, it'll throw an exception and you'll be able to take care of it.