MongoDB: Refactor colname generation in select()
MongoDB: Refactor colname generation in select()

Avoid errors when str(Field) doesn't return 'tablename.fieldname'

niphlod/pydal,stephenrauch/pydal,willimoa/pydal,michele-comitini/pydal,manuelep/pydal,web2py/pydal,kmcheung12/pydal