Python errors: I should have known that

I needed to write some data to a MySQL database. I set up the MySQL Python connector without any real trouble. I tested it in a tiny Python page and it does connect to the correct database. Great!

I moved the connection code to a function on a new page and ran into trouble. I kept seeing a message saying something about “Reference error: weakly-referenced object no longer exists”. After a detour into weak references, I realized the issue was garbage collecting. Somewhere within my function, I had a object that was disappearing.

The connection function had no parameters. A connection object local to the function was created and the resulting cursor was returned. You should see the problem immediately. The connection object what the item that was disappearing. I rewrote the function to send back the connection object and then extract the cursor from the returned object. That error message went away.

I had another strange problem where updating a field was not allowed because of a type mismatch. I’m used to PHP, where weak or loose types are the norm. Once I realized that data going into the MySQL table also needs to match the correct type expected by the MySQL column, my problem is solved.

Advertisements