Re: Trapping SQLException in D2W
Re: Trapping SQLException in D2W
- Subject: Re: Trapping SQLException in D2W
- From: Chuck Hill <email@hidden>
- Date: Wed, 24 Aug 2011 07:29:45 -0700
Hi Markus,
On 2011-08-24, at 1:49 AM, Markus Ruggiero wrote:
> Folks,
>
> I have the following requirement: I need a unique constraint on the combination of 2 attributes. As I have learned from some postings about a year back the distinct index in EOModeler does not work (and it surely does not for me). Or should it?
No, the indexing is not ready for use.
> This is Oracle 9 and WO54, Eclipse Ganymed and suitable WOLips. So to at least to ensure the integrity of the data I have defined a unique constraint via SQL. But now I get a very ugli looking SQLException. This is functionally ok but for the user not acceptable (understandable).
>
> How can I trap such an Exception during SAVE in a (ER)D2W app and present a nice looking error message (similar to what is shown when some validations fail)?
>
> Thanks a lot and have a nice day
> ---markus---
It is tricky. The response from every database is different so you need some database specific code to interpret the exception. I think the best way is to use an EOEditingContext (ERXEC for Wonder apps) sub-class that catches the exception from saveChanges(), and interprets the exception. Done like that, it should be transparent to D2W. I have this implemented for some databases (Oracle is one of them!), in our GVC libraries but have not moved this to Wonder. I started a project in 2009 to complete this validation work and port to Wonder, but uh, er, it kind of fell off the top of my priority list. :-) The base, non-Wonder, code is here: http://sourceforge.net/projects/wovng/ You can get the "used in production" code from our Open Source frameworks: http://www.global-village.net/chill/gvc_frameworks The WOCommunity site has my presentation from WOWODC 2009: http://www.wocommunity.org/podcasts/wowodc/west09/WOWODCW09-Validation.mov
Chuck
--
Chuck Hill Senior Consultant / VP Development
Practical WebObjects - for developers who want to increase their overall knowledge of WebObjects or who are trying to solve specific problems.
http://www.global-village.net/products/practical_webobjects
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