Example of embedding multiple collections in a HAL payload within Apigility.

module.config.php

<?php
return array(
    /* ... */
    'zf-hal' => array(
        'metadata_map' => array(
            /* ... */
            'Api\V1\Rest\Classes\ClassesEntity' => array(
                'entity_identifier_name' => 'name',
                'route_name' => 'api.rest.classes',
                'route_identifier_name' => 'class_name',
                'hydrator' => 'Zend\Stdlib\Hydrator\ClassProperty',
            ),
            'Api\V1\Rest\Classes\ClassesCollection' => array(
                'entity_identifier_name' => 'name',
                'route_name' => 'api.rest.classes',
                'route_identifier_name' => 'class_name',
                'is_collection' => true,
            ),
            'Api\V1\Rest\Properties\PropertiesEntity' => array(
                'entity_identifier_name' => 'name',
                'route_name' => 'api.rest.properties',
                'route_identifier_name' => 'prop_name',
                'hydrator' => 'Zend\Stdlib\Hydrator\ClassProperty',
            ),
            'Api\V1\Rest\Properties\PropertiesCollection' => array(
                'entity_identifier_name' => 'name',
                'route_name' => 'api.rest.properties',
                'route_identifier_name' => 'prop_name',
                'is_collection' => true,
            ),
            /* ... */
        ),
    ),
    /* ... */
);

QueryController.php

<?php
/* We'll assume that all of the above classes are defined.
 *
 * We'll assume that Api\V1\Rpc\Query\QueryController will handle an RPC service
 * call to /search?s=thing. It needs to be configured such that it responds to 
 * GET requests, and Content Negotiation is set to HalJson.
 *
 * This is what it will look like:
 */

namespace Api\V1\Rpc\Query;

use Zend\Mvc\Controller\AbstractActionController;
use ZF\ContentNegotiation\ViewModel;
use ZF\Hal\Entity;

class QueryController extends AbstractActionController
{
    public function queryAction()
    {
        $search = $this->queryParam('s', '');

        /*
         * Do some work, create a ClassesCollection $classes
         * Do some work, create a PropertiesCollection $properties
         *
         * In each case, call $object->setItemCountPerPage(-1) to disable pagination,
         * if they are paginators. (Ignore, if they are not.)
         */

        $data = [
            'query'      => $search,
            'classes'    => $classes,
            'properties' => $properties,
        ];
        $entity = new Entity($data);

        return new ViewModel([ 'payload' => $entity ]);
    }
}

/* The above will be rendered as a single HAL entity, with no links (unless you 
 * inject some yourself), and two embedded collections, one for classes, one 
 * for properties. Each item in each collection will be a HAL resource itself,
 * and properly linked to its source.
 */