[Dbix-class] Runtime database name and table name changes + Catalyst

[James R. Leu]

Hello Matt,

Thank you for your response.  Your recommendation has started me down the
right path.  I have a working implementation, but I'm not sure if I'm
following proper DBIx::Class practices.

I've implemented a template source 'Foo' which is used for
defining the relationships.  In addition I implemented a ACCEPT_CONTEXT
in my Catalyst::Model::DBIC::Schema.

Here is a simplified version of what I've done, I've framed it in
Catalyst code, but I my question at this point is specific to my
DBIx::Class handling:

package MyApp::Model::Config
use base 'Catalyst::Model::DBIC::Schema';

...

sub ACCEPT_CONTEXT {
    my ($self, $c) = @_;
    if ($c->user_exists) {
	my $name = $c->user->username;
	$self->{connect_info} = [
	    'DBI:mysql:config_'.$name,
            'username',
            'password',
	];
	my $schema = $self->clone();
	$schema->source('Foo')->name('data.foo_01');
	$schema->connection(@{$self->{connect_info}});
	$self->schema($schema);
    }
    return $self;
}
1;

Am I conducting an layer violations by calling connection() and source()?
Do I need special handling for when the connection has already been created?

I have other questions about Catalyst, but I will ask those on the
Catalyst mailing list.

Thank you for your time.

On Wed, Jan 24, 2007 at 09:15:21AM +0000, Matt S Trout wrote:
> 
> On 23 Jan 2007, at 21:34, James R. Leu wrote:
> 
> >Disclaimer:
> >I'm a noob to DBIx::Class. I checked the archives, but was unable to
> >find an answer to the following question.  If I've overlooked an  
> >obvious
> >source to my answers, please scold me and point me the the relevant  
> >URL.
> >
> >Hello,
> >
> >I'm trying to use DBIx::Class to access a database for which the name
> >changes based on who is authenticated.  In addition the authorization
> >of the use affects what dynamically name table they 'link' to in  
> >another
> >database.
> >
> >I read about DBIx::Class::Schema::Loader, but was unable to grok
> >how I would define relationships to a dynamically named table.
> >
> >To better illustrate here is a simplified example:
> >
> >    The following database reside within a common mysql instance.
> >
> >    Database: config_alpha
> >	    Table: common
> >
> >    Database: config_beta
> >	    Table: common
> >
> >    Database: data
> >	    Table: foo_01
> >	    Table: foo_88
> >	    Table: foo_34
> >	    Table: foo_39
> >
> >Depending which user logged in 'alpha' or 'beta' they would
> >connect to the appropriate 'config' database.  In addition they are
> >connected the the 'data' database.  Depending on additional
> >authorization data they would have permission to see data in one of  
> >the
> >'foo' tables.  I would like to define a has_many relationship between
> >entries in the 'common' and the 'foo' table.
> >
> >I think I can image ways to make some of this work in a stand-alone
> >script, but I haven't the foggiest idea how to make this work within
> >a Catalyst environment.
> >
> >Any pointers would be much appreciated.
> 
> Ok, basically, define a has_many across to 'data.PLACEHOLDER', then  
> wrap ->connect so on the schema object -to be returned-, which will  
> have a copy of the ResultSource objects, then if your Foo_* tables  
> are different you'll want -
> 
> $schema->source('Common')->relationship_info 
> ('data_has_many_rel_name')->{source} = 'Foo_1';
> 
> or similar, or if your foo_* tables are all the same define a single  
> Foo class and
> 
> $schema->source('Foo')->name('data.foo_1');
> 
> then return the $schema.
> 
> For doing this dynamically in Catalyst on a per-user basis I'd  
> provide an ACCEPT_CONTEXT method in your DBIC::Schema model -
> 
> sub ACCEPT_CONTEXT {
>   my ($self, $c) = @_;
>   if ($c->user_exists) {
>     return $self->copy_and_modify_schema_with_user($c->user);
>   } else {
>     return $self;
>   }
> }
> 
> -- 
> Matt S Trout, Technical Director, Shadowcat Systems Ltd.
> Offering custom development, consultancy and support contracts for  
> Catalyst,
> DBIx::Class and BAST. Contact mst (at) shadowcatsystems.co.uk for  
> details.
> + Help us build a better perl ORM: http://dbix- 
> class.shadowcatsystems.co.uk/ +
> 

-- 
James R. Leu
jleu at mindspring.com
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