Passing Database handles to other modules. #2

nmerriweather has asked for the wisdom of the Perl Monks concerning the following question:

My question is similar to this one posted 1 year ago Passing Database handles to other modules.

I'm building a little application in mod_perl, and have written the bulk of database connectivity into its own package (myApp::DB) , so that I can easily access database handles.

Currently, I open a connection to the database in the 'main' perl script that sets the apache handler. ( my $dbh = myApp::DB->dbconnect(); # returns a ref)

I then either pass the reference around to supplementary packages that need it.

I've been working on a custom form processing package however, that needs to handle certain SQL select statements.

Which is where my problem now comes in:
Right now, the form validation package is built as a generic package that I can reuse. I'm passing in a ref to the dbh when needed -- and that works fine, but its a little annoying, as I feel that I'm passing the ref around alot.

I've considered subclassing my form validator, to have a getDBH function on an init. I've also considered not passing refs around, and just calling connects repeatedly, and letting apache::dbi handle the intercepting.

Both those solutions seem equally as inefficient as the one I've currently got.

Can anyone reccommend something that makes more sense?

Comment on Passing Database handles to other modules. #2

Replies are listed 'Best First'.
Re: Passing Database handles to other modules. #2 by diotalevi (Canon) on May 10, 2004 at 21:17 UTC
I wrote Class::WeakSingleton just so I could have a handle that would be everywhere I wanted it but would still go away when I threw away all the references to it.	[reply]
Re: Passing Database handles to other modules. #2 by perrin (Chancellor) on May 10, 2004 at 20:49 UTC
I typically just have an accessor, similar to yours, for grabbing a dbh. Then I can call it whenever I need to, and never pass around the handle. If you're using Apache::DBI, it's lightweight, and if you are really worried about it you can cache the dbh in $r->pnotes(), which gets automatically cleared after every request.	[reply]
Re: Passing Database handles to other modules. #2 by adrianh (Chancellor) on May 10, 2004 at 21:44 UTC
Right now, the form validation package is built as a generic package that I can reuse. I'm passing in a ref to the dbh when needed -- and that works fine, but its a little annoying, as I feel that I'm passing the ref around alot. Is the form validation package functional/procedural or object oriented? If the former maybe you want to consider moving to the latter so you can have the $dbh become part of the object state and only pass it the once at object creation time.	[reply]
Re: Re: Passing Database handles to other modules. #2 by nmerriweather (Friar) on May 10, 2004 at 23:25 UTC
It is indeed oop, and thats a method that i've played with!	[reply]
Re^3: Passing Database handles to other modules. #2 by adrianh (Chancellor) on May 12, 2004 at 14:10 UTC
It is indeed oop, and thats a method that i've played with! In that case, if you're still finding that you're creating lots of instances of your validation object in different places, I'd suspect that there is a layer of abstraction that's being missed somewhere. Are their other arguments that are similar between multiple instances? Would it make sense to make a factory object of some kind for creating similar validation objects? I'd tend to want to keep passing in the ref somewhere because it keeps everything decoupled and makes testing easier.	[reply]