How to structured data in custom WebAPI?

Question

I have created custom webapi using https://www.demacmedia.com/extending-magento-2-rest-web-api/ This is the code that I am using:

<?php
namespace Panda\WebService\Model\Resource;
use Panda\WebService\Api\WebServiceRepositoryInterface;
use Magento\Catalog\Model\CategoryFactory;
use Magento\Catalog\Model\ResourceModel\Product\CollectionFactory as ProductCollectionFactory;
use Magento\Framework\App\ResourceConnectionFactory;
use Magento\Customer\Model\CustomerFactory;
use Magento\Customer\Model\Address;
/**
 * Class WebServiceRepository
 * @package Panda\WebService\Model
 */
class WebServiceRepository implements WebServiceRepositoryInterface
{
    /**
     * @var ResourceConnectionFactory
     */
    protected $_resourceConnection;
    /**
     * @var ProductCollectionFactory
     */
    protected $_productCollection;
    /**
     * @var CategoryFactory
     */
    protected $_category;
    /**
     * @var CategoryFactory
     */
    protected $_customer;
    /**
     * @var Address
     */
    protected $_address;
    /**
     * @var \Magento\Framework\Json\Helper\Data
     */
    protected $_jsonHelper;
    /**
     * WebServiceRepository constructor.
     *
     * @param ResourceConnectionFactory $_resourceConnection
     */
    public function __construct(
        ResourceConnectionFactory $_resourceConnection, 
        ProductCollectionFactory $_productCollection, 
        CategoryFactory $_category,
        CustomerFactory $_customer,
        Address $address,
        \Magento\Framework\Json\Helper\Data $jsonHelper
    )
    {
        $this->_resourceConnection = $_resourceConnection;
        $this->_productCollection = $_productCollection;
        $this->_category = $_category;
        $this->_customer = $_customer;
        $this->_address = $address;
        $this->_jsonHelper = $jsonHelper;
    }

    /**
     * @return int
     */
    public function getCatalogProductCount()
    {
        return $this->_productCollection->create()->getSize();
    }
    /**
     * @param $categoryId
     *
     * @return int
     */
    public function getCategoryProductCount($categoryId)
    {
        $size = 0;
        $category = $this->_category->create()->load($categoryId);
        if (isset($category) && !empty($category)) {
            $size = $category->getProductCollection()->getSize();
        }
        return $size;
    }

    /**
     * @param $customerId
     *
     * @return int
     */
    public function getCustomer($customerId)
    {
        $customerData = array();
        $customerModel = $this->_customer->create();
        $customer = $customerModel->load($customerId);
        if (isset($customer) && !empty($customer)) {
            $customerData['UserName'] = $customer->getEmail();
            $customerData['IDClient'] = $customer->getId();
            $customerData['ID'] = $customer->getId();
            $customerData['SuccExterne'] = $customer->getData('succexterne');
            $customerData['LastName'] = $customer->getLastname();
            $customerData['FirstName'] = $customer->getFirstname();
            $customerData['BirthDate'] = $customer->getDob();
            $customerData['Email'] = $customer->getEmail();
            $customerData['Language'] = $customer->getData('language');
            $customerData['Gender'] = $customer->getGender();
            $customerData['ConsentementC28'] = $customer->getData('consentementc28');
            $customerData['CardNo'] = $customer->getData('cardno');
            $customerData['Externe'] = $customer->getData('externe');
            $updateTimeStamp = strtotime($customer->getUpdatedAt());
            $customerData['ModificationDate'] = date('Y-m-d', $updateTimeStamp);
            $childId = $customer->getData('child_customer_id');

            // Get Address
            $billingID =  $customer->getDefaultBilling();
            $shippingID =  $customer->getDefaultShipping();

            if(!empty($billingID) && isset($billingID)) {
                $billingAddress = $this->_address->load($billingID);
                $streetAddress = implode(', ', $billingAddress->getStreet());
                $customerData['Address'] = $streetAddress;
                $customerData['City'] = $billingAddress->getCity();
                $customerData['Province'] = $billingAddress->getRegion();
                $customerData['Country'] = $billingAddress->getCountryId();
                $customerData['PostalCode'] = $billingAddress->getPostcode();
                $customerData['Phone'] = $billingAddress->getTelephone();
            } elseif (!empty($shippingID) && isset($shippingID)) {
                $shippingAddress = $this->_address->load($shippingID);
                $streetAddress = implode(', ', $shippingAddress->getStreet());
                $customerData['Address'] = $streetAddress;
                $customerData['City'] = $shippingAddress->getCity();
                $customerData['Province'] = $shippingAddress->getRegion();
                $customerData['Country'] = $shippingAddress->getCountryId();
                $customerData['PostalCode'] = $shippingAddress->getPostcode();
                $customerData['Phone'] = $shippingAddress->getTelephone();
            }

            // Get Child Customer
            if($childId) {
                $childCustomer = $customerModel->load($childId);
                $customerData['CHILDREN'] = [
                                                'ID' => $childId,
                                                'ParentID' => $customerId,
                                                'LastName' => $childCustomer->getLastname(),
                                                'FirstName' => $childCustomer->getFirstname(),
                                                'Gender' => $childCustomer->getGender(),
                                                'BirthDate' => $childCustomer->getDob(),
                                                'Deleted' => false
                                            ];
            }

        }
        return $customerData;
        // echo $this->_jsonHelper->jsonEncode($customerData);
        exit(0);
    }
}

When I return single data then there is no problem, but when I return json or array then it doesn't format that in proper json. Can someone help?

Answer 1

To be able to return complex types from your custom web API endpoint, specify reference to data interface as your return type.

/**
 * @param $customerId
 * @return \YourNamespace\Api\CustomInterface
 */
public function getCustomer($customerId)

Where \YourNamespace\Api\CustomerInterface should be similar to

\Magento\Customer\Api\Data\CustomerInterface in core, it should contain corresponding setters and getters for every field. Every field may in its turn reference scalar type, another data interface or an array of scalar types or data interfaces.