zf2 view strategy, ViewEvent Renderer is always null - zend-framework2

Question

I am trying to implement View Strategy in ZF2.
As far as the basic setup, everything seem to be working fine except that ViewEvent Renderer is always null, thus the renderer never gets injected to the Strategy, and TemplateResolver still requests a template and displays the following error.
PhpRenderer::render: Unable to render template "api/api/get"; resolver could not resolve to a file'
I have even tried to copy the code JsonModel and JsonStrategy from ZF2, and still get the same result.
ViewYamlStrategy.php
public function selectRenderer(ViewEvent $e)
{
$renderer = $e->getRenderer(); // Always return null
}
module.php
public function getServiceConfig()
{
return ['factories' => [
'ViewYamlRenderer' => "Namespace\Mvc\Service\ViewYamlRendererFactory",
'ViewYamlStrategy' => "Namespace\Mvc\Service\ViewYamlStrategyFactory",
],
];
}
module.config.php
'view_manager' => [
'strategies' => [
'ViewYamlStrategy'
],
],
controller
public function getList()
{
return new YamlModel($data);
}
ViewYamlStrategy.php
function __construct(ViewYamlRenderer $renderer)
{
$this->renderer = $renderer;
}
public function attach(EventManagerInterface $events, $priority = 1)
{
$this->listeners[] = $events->attach(ViewEvent::EVENT_RENDERER, [$this, "selectRenderer"], $priority);
$this->listeners[] = $events->attach(ViewEvent::EVENT_RESPONSE, [$this, "injectResponse"], $priority);
}
public function selectRenderer(ViewEvent $e)
{
$renderer = $e->getRenderer();
if ($this->renderer !== $renderer) {
return;
}
}
public function injectResponse(ViewEvent $e)
{
$renderer = $e->getRenderer(); // Always null
if ($this->renderer !== $renderer) {
return;
}
$result = $e->getResult();
$response = $e->getResponse();
$response->setContent($result);
}
ViewYamlRenderer.php
public function render($nameOrModel, $values = null)
{
return $nameOrModel->serialize();
}
public function setResolver(\Zend\View\Resolver\ResolverInterface $resolver)
{
$this->resolver = $resolver;
}
YamlModel.php
protected $captureTo = null;
protected $terminate = true;
public function serialize()
{
/*Serialize Object and return a string*/
}
thanks

Answer 1

I think this is due to the order that the strategies/listeners are triggered; As once a ViewRender is found the event propagation is halted and that renderer is returned.
It seems that the standard PhpRenderStrategy has a default event priority of 1 and the others (JsonStrategy etc) seem to fire prior to this (with an even priority of 100)
Try changing the $priority; perhaps 101
$this->listeners[] = $events->attach(
ViewEvent::EVENT_RENDERER,
[$this, "selectRenderer"],
101 // <-- change here
);

Answer 2

I have finally found the issue.
ViewYamlStrategy.php
/* This should return a renderer */
public function selectRenderer(ViewEvent $e)
{
// here I was checking the Renderer which was not created yet
// and instead I should've checked the model
$model = $e->getModel();
if (!$model instanceof YamlModel) {
return;
}
return $this->renderer;
}