SelectResults are great

One change I made as the website has evolved is to switch from using SQLObject RelatedJoin and MultipleJoin to their cousins, SQLRelatedJoin and SQLMultipleJoin. After having used them, I hazard to say that I think they should be the default. The non-SQL versions return lists of objects; the SQL versions return a SelectResult.

A SelectResult (which of course is also returned from Class.select()) doesn't actually contain the results of the select, but it knows how to get it. It waits to hit the database until actually dereferenced. If you have a SelectResult instead of an actual list of objects, it's not too late to further filter or modify the result!

I had several places in my code where I was iterating through a RelatedJoin, performing a filter in Python. Switching these to SQLRelatedJoins allowed me to ask the database to perform the filter instead, thus reducing the amount of code, as well as helping performance.

The one thing to watch out for: to determine if the SelectResults actually has any rows, you need to call class.results.count() instead of len(class.results), since class.results isn't a list anymore.