ZF2 Configuration Injection Or NOT?

I've googled a lot and read as much as I can on the subject but I cannot find a direct answer to my question anywhere including here. My ZF2 application consists of roughly 7 different modules. 5 of the modules will need access to the same database configuration. The application itself has a database with roughly 124 different tables. So the idea here is to find the proper solution to write the least amount of code considering the setup.

What I'm trying to do is create a specific class to interface with the DB. Where the business logic is kept in the Module and note the controllers to keep everything more abstract and easier to maintain. By that I mean controller X should be able to create a new instance of for instance (Application\Model\DBInterface) and use the models functions to do inserts deletes updates joins selects and so forth. The reason I would like to do it this way is so that all modules installed can use the same interface without having to write endless DI statements everywhere. So what I will need is an example of how I can get the configuration for the DB (currently inside module.config.php + local.php(username / pw)) to be passed to the Application\Model\DBInterface dbConfig variable, and perhaps even an instance of the dbAdapter initialized from config if possible.

Alternatively I could potentially grab the configuration from the Application\Model\DBInterface if such a way exists.

If neither of the above is possible then I can always go back to the old way of doing things by reading an ini file for the db details and instantiating my db adapter that way.

Please keep in mind that I won't be injecting anything in the controllers as the controllers just use $db = new \Application\Model\DBInterface() so injecting into the controllers doesn't make much sense at all.

Is there a better way to do this / optimized / am I doing it completely wrong? Anyone able to share some details please. I've spent way too much time on this already and definitely need help.

Okay, so @Ocramius did just let me know what my misconception with the initializers was and helped me out a bit in understanding it. So here is a probably working solution to your Problem. My understanding about your problem is:

"How to get a DbAdapter set for all your Models implementing a DbInterface". This is how you'd do it:

Step 1: Create invokables for all classes implementing the DbInterface. Create a factory for the default Zend\Db\Adapter\Adapter and then create an initializer for your DbInterface

Module.php getServiceConfig()

return array(
    'invokables' => array(
        'application-model-one' => 'Application\Model\One',
        'application-model-two' => 'Application\Model\Two'
    ),
    'factories' => array(
        'Zend\Db\Adapter\Adapter' => 'Zend\Db\Adapter\AdapterServiceFactory'
    ),
    'initializers' => array( 
        'DbInterfaceInitializer' => function($instance, $sm) {
            if ($instance instanceof \Application\Model\DBInterface) {
                $instance->setDbAdapter($sm->get('Zend\Db\Adapter\Adapter'));
            }
        },
    )
)

The Zend\Db\Adapter\Adapter is using the top-level-configuration-array-key 'db' to automatically inject the dbParams

Step 2: Create your classes implementing your Interface

Application\Model(One|Two|N).php

namespace Application\Model;

class One implements DbInterface, \Zend\Db\Adapter\AdapterAwareInterface
{
    /**
     * @var \Zend\Db\Adapter\Adapter $dbAdapter
     */
    protected $dbAdapter;

    public function setDbAdapter(\Zend\Db\Adapter\Adapter $dbAdapter) {
        $this->dbAdapter = $dbAdapter;
    }

    public function getDbAdapter() {
        return $this->dbAdapter;
    }

    // More of your business logic or data here
}

Step 3: Access those classes with the ServiceLocator from your Controllers

SomeController.php someAction()

$dbOne = $this->getServiceLocator()->get('application-model-one');
$dbTwo = $this->getServiceLocator()->get('application-model-two');
// Adapter will automatically be injected

When accessing the invokable from the ServiceManager the initializer will be called. The initializer then will automatically call the Zend\Db\Adapter\Adapter, which in turn get's the parameters from the configuration key 'db'

You may get more information from once the tutorial Application as well as the blog of samsonasik: ServiceManager Cheat-Sheet