On 04/03/2011 2:00 PM, Oleg Broytman wrote:
On Fri, Mar 04, 2011 at 12:49:50PM +0000, Timothy W. Grove wrote:
It seems to me that there should be a simple way to add the attribute to  
the class if the column has been added already, or not if it has been  
added through updating
   There is no a simple way. You have to create the table class without
the column, and then look into the database to determine if the column
is there. You can use the same mechanism SQLObject uses to implement
fromDatabase: connection.columnsFromSchema(tableName, soClass); the
result is a list of SOCol instances.
Thanks for the advice, Oleg. I found a solution which may not be elegant, but it works for me! Instead of trying to work with two different class definitions I've just kept one which declares the column I wish to add to the database and run an update function which deletes the column from the class before adding it again to both the class and the database. My example follows.

Best regards,
Tim

class SignEntry(SQLObject):       
    explanatory_map = PickleCol()
def SignEntryUpdate():
    cols = [i.name for i in sqlhub.processConnection.columnsFromSchema("sign_entry", SignEntry)]
    if 'explanatoryMap' not in cols:
        SignEntry.sqlmeta.delColumn('explanatory_map') # I know this exists in the class definition
        SignEntry.sqlmeta.addColumn(PickleCol("explanatory_map"), changeSchema=True)