Cannot generate HalResource for object of type ArrayObject - hal

Question

I've some problems to return a paginator object as HAL json collection. I'm using the latest versions of zend-expressive and zend-expressive-hal.
This is the setting from my ConfigProvider:
public function __invoke() : array
{
return [
'dependencies' => $this->getDependencies(),
MetadataMap::class => $this->getHalConfig(),
];
}
public function getHalConfig() : array
{
return [
[
'__class__' => RouteBasedCollectionMetadata::class,
'collection_class' => RoleCollection::class,
'collection_relation' => 'user_roles',
'route' => 'api.user.roles',
],
];
}
And these are my handler methods:
public function get(ServerRequestInterface $request) : ResponseInterface
{
// read some records from the database
$select = new Select();
$select->from(['r' => 'user_roles']);
$select->columns(['id', 'name']);
$paginator = new RoleCollection(new DbSelect($select, $this->dbAdapter));
$paginator->setItemCountPerPage(25);
$paginator->setCurrentPageNumber(1);
return $this->createResponse($request, $paginator);
}
private function createResponse(ServerRequestInterface $request, $instance) : ResponseInterface
{
return $this->responseFactory->createResponse(
$request,
$this->resourceGenerator->fromObject($instance, $request)
);
}
The RoleCollection class is only an inheritance of the Paginator:
class RoleCollection extends Paginator
{
}
The error message which I get is:
Cannot generate Zend\Expressive\Hal\HalResource for object of type ArrayObject; not in metadata map

Answer 1

I think you are missing the metadata for the Role object itself.
For example this is something similar for my posts object:
MetadataMap::class => [
[
'__class__' => RouteBasedCollectionMetadata::class,
'collection_class' => Posts::class,
'collection_relation' => 'posts',
'route' => 'api.posts',
],
[
'__class__' => RouteBasedResourceMetadata::class,
'resource_class' => Post::class,
'route' => 'api.posts.view',
'extractor' => ArraySerializable::class,
],
],
You have only described the collection and the resource class is missing for a single role.
I also see the resource generator tries to parse an ArrayObject. This should be wrapped in a Role object, which you can add to the MetadataMap.
Where it goes wrong in your code is this line:
$paginator = new RoleCollection(new DbSelect($select, $this->dbAdapter));
This adds the result of a query into the paginator, but the paginator does not know how to handle it. If I remember correctly, the DbSelect return a ResultSet. I'm guessing this is where the ArrayObject is coming from. What you probably need is to override that ResultSet and make sure it returns an array of Role objects. You might want to look into the dbselect adapter and the hydrating resultset.
Once you have the Role object in the paginator, you can describe it in the metadata.
[
'__class__' => RouteBasedResourceMetadata::class,
'resource_class' => UserRole::class,
'route' => 'api.roles',
'extractor' => ...,
],
I use doctrine myself with hal so zend-db is out of my scope. If you need more help, I suggest the zf forums.