filter_loaded_credentials

    sub filter_loaded_credentials {
        my ( $class, $loaded_credentials, $connect_args ) = @_;
        ...
        return $loaded_credentials;
    }

$loaded_credentials is the structure after it has been loaded from the configuration file. In this case, "$loaded_credentials->{user}" eq WalterWhite and "$loaded_credentials->{dsn}" eq DBI:mysql:database=students;host=%s;port=3306.

$connect_args is the structure originally passed on "->connect()" after it has been turned into a hash. For instance, "->connect('DATABASE', 'USERNAME')" will result in "$connect_args->{dsn}" eq DATABASE and "$connect_args->{user}" eq USERNAME.

Additional parameters can be added by appending a hashref, to the connection call, as an example, "->connect( 'CONFIG', { hostname => "db.foo.com" } );" will give $connect_args a structure like "{ dsn => 'CONFIG', hostname => "db.foo.com" }".

For instance, if you want to use hostnames when you make the initial connection to DBIC and are using the configuration primarily for usernames, passwords and other configuration data, you can create a config like the following:

    DATABASE:
        dsn: "DBI:mysql:database=students;host=%s;port=3306"
        user: "WalterWhite"
        password: "relykS"

In your Schema class, you could include the following:

    package My::Schema
    use warnings;
    use strict;
    use base 'DBIx::Class::Schema::Config';

    sub filter_loaded_credentials {
        my ( $class, $loaded_credentials, $connect_args ) = @_;
        if ( $loaded_credentials->{dsn} =~ /\%s/ ) {
            $loaded_credentials->{dsn} = sprintf( $loaded_credentials->{dsn},
                $connect_args->{hostname});
        }
    }
    
    __PACKAGE__->load_classes;
    1;

Then the connection could be done with "$Schema->connect('DATABASE', { hostname =" 'my.hostname.com' });>

See "load_credentials" for more complex changes that require changing how the configuration itself is loaded.

load_credentials

If you take the route of having "->connect('DATABASE')" used as a key for whatever configuration you are loading, DATABASE would be "$config->{dsn}"

    Some::Schema->connect( 
        "SomeTarget", 
        "Yuri", 
        "Yawny", 
        { 
            TraceLevel => 1 
        } 
    );

Would result in the following data structure as $config in "load_credentials($class, $config)":

    {
        dsn             => "SomeTarget",
        user            => "Yuri",
        password        => "Yawny",
        TraceLevel      => 1,
    }

Currently, load_credentials will NOT be called if the first argument to "->connect()" looks like a valid DSN. This is determined by match the DSN with "/^dbi:/i".

The function should return the same structure. For instance:

    package My::Schema
    use warnings;
    use strict;
    use base 'DBIx::Class::Schema::Config';
    use LWP::Simple;
    use JSON

    # Load credentials from internal web server.
    sub load_credentials {
        my ( $class, $config ) = @_;

        return decode_json( 
            get( "http://someserver.com/v1.0/database?key=somesecret&db=" . 
                $config->{dsn}  ));
    }
    
    __PACKAGE__->load_classes;