Overriding ZF2 global/local config: unsetting - zend-framework

Question

I've run into a problem where my local config overrides global but I need local to remove not just override.
E.g.
// global.php
'mail_transport' => [
'type' => 'Zend\Mail\Transport\Smtp',
'options' => [
'host' => 'smtp.gmail.com',
'port' => 587,
'connectionClass' => 'login',
'connectionConfig' => [
// ...
],
],
], // ...
// local.php
'mail_transport' => [
'type' => 'Zend\Mail\Transport\File',
'options' => [
'path' => 'data/mail/',
]
],
// ...
So, mail_transport is being overridden, yet its options host, port, connectionClass remain and muck up the mail transport factory. Is there any way to override as I'd like? Or is the only way to edit global.php directly?

Answer 1

You can add a listener on the event Zend\ModuleManager\ModuleEvent::EVENT_MERGE_CONFIG to remove the required options.
Zend\ModuleManager\Listener\ConfigListener triggers a special event, Zend\ModuleManager\ModuleEvent::EVENT_MERGE_CONFIG, after merging all configuration, but prior to it being passed to the ServiceManager. By listening to this event, you can inspect the merged configuration and manipulate it.
Such a listener could look like this.
use Zend\ModuleManager\ModuleEvent;
use Zend\ModuleManager\ModuleManager;
use Zend\ModuleManager\Feature\InitProviderInterface;
class Module implements InitProviderInterface
{
public function init(ModuleManager $moduleManager)
{
$events = $moduleManager->getEventManager();
$events->attach(ModuleEvent::EVENT_MERGE_CONFIG, [$this, 'removeMailOptions']);
}
public function removeMailOptions(ModuleEvent $event)
{
$listener = $event->getConfigListener();
$config = $listener->getMergedConfig(false);
if (isset($config['mail_transport']['type'])) {
switch($config['mail_transport']['type']) {
case \Zend\Mail\Transport\File::class :
$config['mail_transport']['options'] = [
'path' => $config['mail_transport']['options']['path']
];
break;
}
}
$listener->setMergedConfig($config);
}
}