[Catalyst] Reading Database At Startup

[John Romkey]

On Aug 16, 2009, at 11:09 AM, Ovid wrote:
> Hi all,
>
> This should be painfully obvious, but I don't see it :)
>
> For a personal project, I want users to be able to click on a letter  
> and get a list of countries starting with that letter.  I can do this:
>
>    my $letters = $c->model('DB')->storage->dbh->selectcol_arrayref(
>        'select distinct(substr(name,1,1)) as letter from country  
> order by letter'
>    );
>    $c->stash->{letters} = $letters;
>
>
> But the country list is static and I want this available at  
> startup.  'sub begin' fails because that's called once per request,  
> not once per app.
>
> What's the recommend way of handling this?  (I'm using DBIx::Class  
> for the model)

I do something like this; on my app I have a list of towns and states  
that I need to build from the database and is fairly static.

What I do is build it on demand and cache the results using  
Catalyst::Plugin::Cache and Catalyst::Plugin::Cache::Store::Memory

Because every page in my app uses this list to provide a list for  
searching these locales, in the auto() handler in Root.pm I check to  
see if the cache entry for the data structure is there and if it's  
not, I create it from the database and cache it. I also cache counts  
of entries in each town. Since these counts can change without me  
restarting the app, I just rebuild the cache when I add or delete a  
listing from a town. I never expire the cache, there's no need.

This means that the first page hit on any instance of the server takes  
a little while longer than usual, but it's really not a significant  
performance hit.
	- john romkey
	http://www.romkey.com/