Re: Data validation, mapping, and error handling

Hi Joe,

What I'm talking about is how it looks to the user. The user doesn't care where you put the edits; most of them wouldn't understand if you tried to explain where they are. What the user sees is what counts. In the case of the VALUES keyword in DDS, when the user enters a value outside the listed VALUES, the keyboard locks, a cryptic message is displayed saying they've entered an invalid value. A typical business rule error message is probably more descriptive of the problem, and may or may not lock the keyboard, highlight the field, position the cursor, or whatever; in other words, it acts differently.

With Aaron's approach, presumably all errors are presented in the same way to the user.

Which led to the question about how EGL's field-related validation actually displays the error to the user. Is it predetermined by EGL? Do you have to define how it shows the errors? Do you (you, Joe, in this case) make your business rule errors show the errors the same way EGL does?

*Peter Dow* /
Dow Software Services, Inc.
909 793-9050
pdow@xxxxxxxxxxxxxxx <mailto:pdow@xxxxxxxxxxxxxxx> /

With the 5250 interface, how the user sees a VALUES or other validation error is probably going to be a lot different than how a business rule validation error is presented. I'd say that's a pro for Aaron's philosophy of putting all the edits in one place.

Not sure I understand this statement. You quote me below where I specifically separate data entry edits, reasonability checks and business rules. My point is that the simpler checks (field required, for example) can be implemented outside of business logic and more specifically in the client code; in rich client applications this allows the edit checks to be made without round trips to the server.

My problem with the "all in one place" theory is that all edits, even smiple checks, should be re-implemented in the business logic itself. Thus, if you want your edits in one place and one place only, they all have to be in the server. My point is that you can save the USER time if you put some of the checks in the client.

But I can also see Joe's argument for having EGL do most of the work (I'm a programmer too :-) ). How does EGL present the validation errors to the user? Is it decent enough that you would have all your business rule validation present the error the same way so the user has a better experience?

Presenting errors in EGL is simple: you place a tag where you want the error text to display. Typically that would be in a cell in a table. To implement your own custom validation, you'd create an message variable and put that in the same cell. That way, the cell would display either the automatic validation error or the error from the server.

Joe