[Maypole] catching DB errors

[Simon Flack]

Toby Corkindale wrote:
> On Wed, Jan 26, 2005 at 01:25:20PM +0000, Simon Flack wrote:
> 
>>Toby Corkindale wrote:
> 
> [snip]
> 
>>>However, I've tried putting an error subroutine into both the main driver
>>>class, and also the model classes too.  In neither case was it actually
>>>called when the DB threw up an error.
>>
>>The 404 response you're getting intrigues me.
>>
>>Assuming your DB throws an error whilst processing a model action, 
>>Maypole will call invoke an 'exception' method in your model class (if 
>>such a method exists), or it will call $r->exception() if it doesn't.
> 
> 
> Ah, thanks.. I hadn't seen that feature before - I'll test it out now.

I doesn't look like it's in the documentation. I'll make a note of that.

> btw, can I put a generic version in the driver class, or does it have to be
> in every model class?

Yes, you can have a generic exception handler in your driver class. It 
just gives a little extra flexibility to be able to define 
model-specific exception handlers, but they're optional.

> I do see error info in the logs, but while in a testing phase I'd like to be
> able to catch the error and display a message including it on-screen..
> It sounds like the exception() method should do the trick for that though.

That sounds like a good idea. Your exception handler will need to return 
Maypole::Constants::OK. A basic exception handler could look like this 
(untested):

	sub BeerDB::exception {
		my ($r, $error) = @_;
		$r->output("You've had too much to drink: $error");
		return Maypole::Constants::OK;
	}

$r->output() sets the output that Maypole will later send to the 
browser. 'output' is a noun here rather than a verb.

While looking at this, I notice that there's already an $r->error() 
which clashes with the $r->error() described in 
Maypole::Manual::Request. We'll need to straighten that out.

Simon