The patch to implement: Validate properties specified for sorting and grouping in index views. Original patch from martin.v.loewis via: https://hg.python.org/tracker/roundup/rev/439bd3060df2 Applied by John Rouillard with some modification to properly identify if the bad property is a sort or grouping property. Tests added. has an issue with the current code base. Apparently sometime it can be entered without self.classname being defined. As a result the property lookup fails. So guard it by checking for self.classname in a couple of spots and if self.classname is not set just append the property and let the target action sort it out.

# In Python 3 the "anydbm" module was renamed to be "dbm" which is now a
# package containing the various implementations. The "wichdb" module's
# whichdb() function was moved to the new "dbm" module.

try:
    # old school first because <3 had a "dbm" module too...
    import anydbm
    from whichdb import whichdb
except ImportError:
    # python 3+
    import dbm as anydbm
    whichdb = anydbm.whichdb