Getting all attributes of products does not work in Magento2

Question

I want to create custom API module that will return the same thing as: /V1/products REST API endpoint.

In order to do that I created the following custom endpoint:

public function __construct(
        \Magento\Catalog\Model\ResourceModel\Product\CollectionFactory $productCollectionFactory,
        \Magento\Catalog\Api\Data\ProductSearchResultsInterfaceFactory $searchResultsFactory,
        \Magento\Framework\Api\ExtensionAttribute\JoinProcessorInterface $extensionAttributesJoinProcessor) {

    $this->productCollection = $productCollectionFactory;
    $this->searchResultsFactory = $searchResultsFactory;
    $this->extensionAttributesJoinProcessor = $extensionAttributesJoinProcessor;
}

/**
 * Return the sum of the two numbers.
 *
 * @api
 * @param string $query.
 * @return \Magento\Framework\Api\SearchResults
 */
public function products($query) {

        $collection = $this->productCollection->create();
        $this->extensionAttributesJoinProcessor->process($collection);

        $collection->addAttributeToSelect('*');
        $collection->joinAttribute('status', 'catalog_product/status', 'entity_id', null, 'inner');
        $collection->joinAttribute('visibility', 'catalog_product/visibility', 'entity_id', null, 'inner');

        $collection->setCurPage(1);
        $collection->setPageSize(100);
        $collection->load();

        $searchResult = $this->searchResultsFactory->create();
        $searchResult->setItems($collection->getItems());
        $searchResult->setTotalCount($collection->getSize());

    return $searchResult;
}

I created it with analogy to core /V1/products/getList:

public function getList(\Magento\Framework\Api\SearchCriteriaInterface $searchCriteria)
{
    /** @var \Magento\Catalog\Model\ResourceModel\Product\Collection $collection */
    $collection = $this->collectionFactory->create();
    $this->extensionAttributesJoinProcessor->process($collection);

    foreach ($this->metadataService->getList($this->searchCriteriaBuilder->create())->getItems() as $metadata) {
        $collection->addAttributeToSelect($metadata->getAttributeCode());
    }
    $collection->joinAttribute('status', 'catalog_product/status', 'entity_id', null, 'inner');
    $collection->joinAttribute('visibility', 'catalog_product/visibility', 'entity_id', null, 'inner');

    //Add filters from root filter group to the collection
    foreach ($searchCriteria->getFilterGroups() as $group) {
        $this->addFilterGroupToCollection($group, $collection);
    }
    /** @var SortOrder $sortOrder */
    foreach ((array)$searchCriteria->getSortOrders() as $sortOrder) {
        $field = $sortOrder->getField();
        $collection->addOrder(
            $field,
            ($sortOrder->getDirection() == SortOrder::SORT_ASC) ? 'ASC' : 'DESC'
        );
    }
    $collection->setCurPage($searchCriteria->getCurrentPage());
    $collection->setPageSize($searchCriteria->getPageSize());
    $collection->load();

    $searchResult = $this->searchResultsFactory->create();
    $searchResult->setSearchCriteria($searchCriteria);
    $searchResult->setItems($collection->getItems());
    $searchResult->setTotalCount($collection->getSize());
    return $searchResult;
}

Nevertheless, my solution return only custom_attributes (no name, no price etc.). It does not return them even if I do so: $collection->addAttributeToSelect('name');

Do you know what can be the reason? I will be really grateful for any help.

Additionally I upload my di.xml file:

<preference for="tommyjs\Products\Api\ProductsInterface"
            type="tommyjs\Products\Model\ProductsEndpoint" />

<type name="tommyjs\Products\Model\ProductsEndpoint">
    <arguments>
        <argument name="productCollectionFactory" xsi:type="object">\Magento\Catalog\Model\ResourceModel\Product\CollectionFactory</argument>
    </arguments>
</type>

---

SOLUTION

I resolved the problem by replacing:

/**
 * Return the sum of the two numbers.
 *
 * @api
 * @param string $query.
 * @return \Magento\Framework\Api\SearchResults
 */
public function products($query) {

with

/**
 * Return the sum of the two numbers.
 *
 * @api
 * @param string $query.
 * @return \Magento\Catalog\Api\Data\ProductSearchResultsInterface
 */
public function products($query) {

Answer 1

I have implement like you and success. Here you can compare and get result:

#vendor/magento/module-catalog/etc/webapi.xml

<route url="/V1/products1/:query" method="GET">
    <service class="Magento\Catalog\Api\ProductRepositoryInterface" method="products1"/>
    <resources>
        <resource ref="anonymous" />
    </resources>
</route>


#vendor/magento/module-catalog/Api/ProductRepositoryInterface.php

/**
 * Return the sum of the two numbers.
 *
 * @api
 * @param string $query|null.
 * @return \Magento\Framework\Api\SearchResults
 */
public function products1($query);


# vendor/magento/module-catalog/Model/ProductRepository.php

public function products1($query) {
    #\Magento\Catalog\Model\ResourceModel\Product\CollectionFactory $productCollection
    $collection = $this->productCollection->create();
    $this->extensionAttributesJoinProcessor->process($collection);

    $collection->addAttributeToSelect('*');
    $collection->joinAttribute('status', 'catalog_product/status', 'entity_id', null, 'inner');
    $collection->joinAttribute('visibility', 'catalog_product/visibility', 'entity_id', null, 'inner');

    $collection->setCurPage(1);
    $collection->setPageSize(100);
    $collection->load();

    $searchResult = $this->searchResultsFactory->create();
    $searchResult->setItems($collection->getItems());
    $searchResult->setTotalCount($collection->getSize());

    return $searchResult;
}

When I call the command: curl http://mage2ee.local/index.php/rest/V1/products1/1

It's work. In this case query = 1.

Remember always: Remove var folder and flush cache If you edit some .xml file.