Here is the scenario that I need some input on:

A user enters the quantity of widgets that they produced.  They hit the save button.  The production data is stored in table separate from the widget table.  Once the user clicks save, I want the BO to update the On Hand total of the widget in the widget table.  I am thinking that I would place some code in the AfterSave() method to make this happen.  Here's the rub...what if the user entered the wrong quantity (not that this ever happens--I am just doing some just-in-case type of analysis here  ?  The user finds their production data entry and clicks edit, then proceeds to change the quantity and clicks save.  Now, what is the best way of handling this in order to update the widget table with the difference in quantity?

I have some ideas from previous non-SF days, but is there a good SF way to do this?

Thanks,
Bill 

All of these are great ideas...here is another idea that we use.  In fact, I am in the middle of creating some quanity on hand calculations for inventory items within our medical software.  We do not store the quantity on hand in the table at all.  This is better as a calculated field.  You can create a view, user-defined function, or stored procedure to get this amount for you dynamically.  This way it is ALWAYS right and you never have to worry about updating a field (which is the approach that we used in the past).

We have a transaction posting section for our inventory items that allows the end-user to post the purchase of new items, which in turn updates the tran table showing a quantity of X amount that has been added to inventory.  Then there is a transaction posting when the item is actually sold, which then would be a decrement of the QOH.  The view takes all of this into account and returns the value for me....this was a bit of an adjustment to our thinking at first, but has turned out to be MUCH faster, reduce errors, and be a better road to travel altogether.

Bill,

I usually set it to be a single event for each property as Strataframe passes the field name in the event args. However I also have created my own event and event args and then raise the  custom event by adding the logic in the custom code section of the BO mapper.

For instance I handle events on reg and o.t. hours worked and pay rate fields with one event handler. in handling these events I can then recalculate gross pay whenver any of these fields change which in turn raises another event that calculates taxes and updates the check business object's value for withholding taxes etc. So in the Ui when a user changes something the event is raised and handled which then updates other values in other bound business objects causing all the bound controls to automatically refresh which makes things real real nice.

As Trent said views are great!! I write payroll software and in foxpro I keep running totals of week to date hours taxes garnishments etc and year to date hours etc in seperate tables, well these tables always seemed to get screwed up and I would have to run routines to recalc them. I now have all this type of logic in views so no more totals tables and the data is always accurate, so depending on what you need to do a view may be a better choice, hopefully this helps a little.

Guys...great discussion...thank you!!

Let me see, then...to gather the widget on hand quantity I would run a query (in a view) that would do something like this:

Production table (get total of the widgets made) - Shipping table (get total of the widgets shipped) = Total OnHand Quantity

What about inventory counts when actual and on hand do not match?  How are those handled?  Inventory adjustment table?