Re: Own messages for constraints?

On Fri, 2007-03-16 at 20:19 +0100, Kacper Chrapa wrote:
> Hi !
>
> Is it possible in postgres to define own message for some constraint?
>
> Example:
> If i create check constraint on zip_code column , i want to get
> a message: "Zip code is invalid.Please,input code in format: nn-nnn"
> and I want to send this message to the end user.
> It will be much better(in my case) than "violates constraint
> zip_code_check" :-) .
>
> I can make this validation in trigger (and send msg to application by
> notice or raise),but in this case i will duplicate validation
> rules (in trigger and in constraint).Effect: Lower performance(i think)
> and rules in two places...
>

There's no custom message for a CHECK constraint violation.

You can use an AFTER trigger instead of a CHECK constraint (but that may
have a performance impact - test for your application).

You can also give descriptive names to your CHECK constraint which may
help.

It's not a good idea to pass database errors directly back to the user
anyway.

Regards,
Jeff Davis