Hello, I am new to web2py, and this group. I was conversing on IRC and it was suggested by dingding1 that I should post this here.
I think there's a bug with virtualfields. It seems that if I try to use a select() statement with only one field name, then virtualfields will fail to work as it cannot find the other dependent fields it needs to calculate the desired output. So if this is desired behavior, it is not mentioned in the book (3rd ed), and it seems to be counter intuitve as it seems like the virtualclass should have access to all elements regardless of the select query being run on it. see following example code http://pastie.textmate.org/1308330 class MyVirtualFields(object): def production_total(self): return self.production.production_shift_1+self.production.production_shift_2+self.production.production_shift_3 def production_net(self): return self.production.production_shift_1+self.production.production_shift_2+self.production.production_shift_3- self.production.production_rejection def lid_total(self): return self.production.lid_shift_1+self.production.lid_shift_2+self.production.lid_shift_3 #NOTE virtual fields cause a problem with SELCT() statements. In the select statement if you don't include the required fields for the calculation, it will give an error! This is a bug! #crashes on the following query # rows = db(db.production.date_id == date.today()).select(db.production.delivered) #if i comment our the select criteria as shown below, then it works fine # rows = db(db.production.date_id == date.today()).select()#db.production.delivered) db.production.virtualfields.append(MyVirtualFields()) is this a valid, or just flawed understanding on my part? maybe it makes sense to not have virtualfields access to all fields, because that would mean fetching all data from server all the time, thereby slowing down. but then it should allow a switch for disabling it's evaluation or something so that when running code that doesn't require the virtualfield then it can skip the evaluation. Thank you for your patience. Vijay
