How to print the custom error message on DB errors?

[eluser]Unknown[/eluser]
Hi,

I'm using CI 1.7.3 and developing a program which only respond to the client as XML. Users access this service through their client program on the mobile device.

CI prints a pretty formed HTML error message to the client on DB connection or query errors. However, it is useless to me and I want to print a custom XML(represent an error) message without CI default error message.

Is there a way to do this like an error callback handler?

Thank you.

-Brian