Craft\ElementApiController::actionGetElements PHP Method

    public function actionGetElements($configFactory = null, array $config = null)
    {
        if ($configFactory !== null) {
            $params = craft()->urlManager->getRouteParams();
            $variables = isset($params['variables']) ? $params['variables'] : null;
            $config = $this->_callWithParams($configFactory, $variables);
        }
        // Merge in default config options
        $config = array_merge(['paginate' => true, 'pageParam' => 'page', 'elementsPerPage' => 100, 'first' => false, 'transformer' => 'Craft\\ElementApi_ElementTransformer'], craft()->config->get('defaults', 'elementapi'), $config);
        if ($config['pageParam'] == 'p') {
            throw new Exception('The pageParam setting cannot be set to "p" because that’s the parameter Craft uses to check the requested path.');
        }
        if (!isset($config['elementType'])) {
            throw new Exception('Element API configs must specify the elementType.');
        }
        /** @var ElementCriteriaModel $criteria */
        $criteria = craft()->elements->getCriteria($config['elementType'], ['limit' => null]);
        if (!empty($config['criteria'])) {
            $criteria->setAttributes($config['criteria']);
        }
        // Load Fractal
        $pluginPath = craft()->path->getPluginsPath() . 'elementapi/';
        require $pluginPath . 'vendor/autoload.php';
        $fractal = new Manager();
        $fractal->setSerializer(new ArraySerializer());
        // Define the transformer
        if (is_callable($config['transformer']) || $config['transformer'] instanceof TransformerAbstract) {
            $transformer = $config['transformer'];
        } else {
            Craft::import('plugins.elementapi.ElementApi_ElementTransformer');
            $transformer = Craft::createComponent($config['transformer']);
        }
        if ($config['first']) {
            $element = $criteria->first();
            if (!$element) {
                throw new HttpException(404);
            }
            $resource = new Item($element, $transformer);
        } else {
            if ($config['paginate']) {
                // Create the paginator
                require $pluginPath . 'ElementApi_PaginatorAdapter.php';
                $paginator = new ElementApi_PaginatorAdapter($config['elementsPerPage'], $criteria->total(), $config['pageParam']);
                // Fetch this page's elements
                $criteria->offset = $config['elementsPerPage'] * ($paginator->getCurrentPage() - 1);
                $criteria->limit = $config['elementsPerPage'];
                $elements = $criteria->find();
                $paginator->setCount(count($elements));
                $resource = new Collection($elements, $transformer);
                $resource->setPaginator($paginator);
            } else {
                $resource = new Collection($criteria, $transformer);
            }
        }
        JsonHelper::sendJsonHeaders();
        $data = $fractal->createData($resource);
        // Fire an 'onBeforeSendData' event
        craft()->elementApi->onBeforeSendData(new Event($this, ['data' => $data]));
        echo $data->toJson();
        // End the request
        craft()->end();
    }