Python’s If __name__ == “__main__”

For the last few months, I’ve been grabbing data on every game on Board Game Geek.  The script has changed a little bit and I thought it would be a good time to follow up on it.  You can get the script in its entirety here.

The script will sometimes error out for any number of reasons.  Typically, it will be because the BGG website is not available (or it kicks me off for pinging it too many times).  When this happens, I need to restart the script.  Part of the problem with this, though, is that I only commit changes to the database periodically.  That means that the last several games that I grabbed may not be in the database, so when I restart the script I need to look at the last game added.  Before, I would do this query manually in the database, then update the script and rerun it.  This takes some time and can be a pain.  In order to make it easier, I wanted to be able to simply run something from the command line that would do the search and restart the script (something like main_xml.py restart).

To do this, I use the command:

This statement checks to see if the file is the main file being run.  Since the main_xml.py file is the only script we have, it is the main file.  Within that, I check to see if there are any arguments.  To do that, we check the length of sys.argv.  If the length of that is 1, that means there are no arguments.  In that case, it is the first time the script is run so we’ll just grab all of the IDs for each game already in the database:

Otherwise, we will look to see if the argument is ‘restart’.  If it is, we’ll again grab all of the IDs from the database and store it into the idlist.  Next, we’ll see what the last game was that was added to the database, and start the search from there:

The if __name__ == “__main__” loop can be really helpful for many scripts.  It is the perfect way to allow your script to accept arguments from the command line, which will help you make your scripts more reuseable!

 

Have questions or suggestions?  Please feel free to comment below or contact me.

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