Magento – how to get mixed or multi array response in rest API magento2

Below are the custom api module with key pair value
To get JSON response, in client set Response headers to "Content-Type: application/json; charset=utf-8"

and if you need key pair value that is in response should have key and value as like /rest/V1/categories we need to create data interface

To test in Chrome download plugin called rest client app call the url

below module url will be http://yourdomein.com/magento2/rest/V1/getinfo

app\code\Sugarcode\Customapi\registration.php:

<?php
\Magento\Framework\Component\ComponentRegistrar::register(
    \Magento\Framework\Component\ComponentRegistrar::MODULE,
    'Sugarcode_Customapi',
    __DIR__
);

app\code\Sugarcode\Customapi\etc\module.xml:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/Module/etc/module.xsd">
    <module name="Sugarcode_Customapi" setup_version="2.0.0"/>
</config>

app\code\Sugarcode\Customapi\etc\di.xml:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/ObjectManager/etc/config.xsd">

    <preference for="Sugarcode\Customapi\Api\TestInterface"
                type="Sugarcode\Customapi\Model\Test" />

    <preference for="Sugarcode\Customapi\Api\Data\TestdataInterface" type="Sugarcode\Customapi\Model\Testmodel" />
</config>

app\code\Sugarcode\Customapi\etc\webapi.xml:

<?xml version="1.0"?>
<routes xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../app/code/Magento/Webapi/etc/webapi.xsd">

    <!-- Example: curl http://127.0.0.1/index.php/rest/V1/calculator/add/1/2 -->
    <route url="/V1/getinfo" method="GET">
        <service class="Sugarcode\Customapi\Api\TestInterface" method="getinfo" />
        <resources>
            <resource ref="anonymous" />
        </resources>
    </route>

</routes>

app\code\Sugarcode\Customapi\Api\TestInterface.php:

<?php

namespace Sugarcode\Customapi\Api;

use Sugarcode\Customapi\Api\Data\TestdataInterface;

interface TestInterface
{
    /**
     * Retrieve list of info
     *
     * @throws \Magento\Framework\Exception\NoSuchEntityException If ID is not found
     * @return \Sugarcode\Customapi\Api\Data\TestdataInterface containing Tree objects
     */
    public function getinfo();

}

don't remove comments its most important

app\code\Sugarcode\Customapi\Api\Data\TestdataInterface.php (set and get data):

<?php

namespace Sugarcode\Customapi\Api\Data;

/**
 * @api
 */
interface TestdataInterface
{

    /**
     * Get name
     *
     * @return string
     */
    public function getName();

      /**
     * Set name
     *
     * @param string $name
     * @return $this
     */
    public function setName($id);

}

app\code\Sugarcode\Customapi\Model\Test.php:

<?php

namespace Sugarcode\Customapi\Model;

use Sugarcode\Customapi\Api\TestInterface;

/**
 * Defines the implementaiton class of the calculator service contract.
 */
class Test implements TestInterface
{
    /**
     * Return the sum of the two numbers.
     *
     * @api
     * @param int $num1 Left hand operand.
     * @param int $num2 Right hand operand.
     * @return int The sum of the two values.
     */
    protected $dataFactory;
    public function __construct(\Sugarcode\Customapi\Api\Data\TestdataInterfaceFactory $dataFactory)
    {
        $this->dataFactory = $dataFactory;
    }



    public function getinfo() {
        $page_object = $this->dataFactory->create();
        $page_object->setName('Hello');
        return $page_object;        

    }

}

app\code\Sugarcode\Customapi\Model\Testmodel.php:

<?php

namespace Sugarcode\Customapi\Model;

class Testmodel extends \Magento\Framework\Model\AbstractModel implements
    \Sugarcode\Customapi\Api\Data\TestdataInterface 
{
    const KEY_NAME = 'name';


     public function __construct(
        \Magento\Framework\Model\Context $context,
        \Magento\Framework\Registry $registry,
        \Magento\Framework\Model\ResourceModel\AbstractResource $resource = null,
        \Magento\Framework\Data\Collection\AbstractDb $resourceCollection = null,
        array $data = []
    ) {
        parent::__construct($context, $registry, $resource, $resourceCollection, $data);
    }


    public function getName()
    {
        return $this->_getData(self::KEY_NAME);
    }


    /**
     * Set name
     *
     * @param string $name
     * @return $this
     */
    public function setName($name)
    {
        return $this->setData(self::KEY_NAME, $name);
    }


}

There are default REST APIs in Magento2.

1. website ID (or store ID) we have multisite : To filter according to the store or website there is no any REST APIs. To get list of product according to store or website reuired "REST Schema Endpoint Format". For example to get list of product for a single store we use the following call

   http://{baseurl}/rest/V1/products?searchCriteria[pageSize]=10
   

   suppose you have another store with store code "store2". then we use following url

   http://{baseurl}/rest/store2/V1/products?searchCriteria[pageSize]=10
   

   For more detail REST Schema end point

List of avail APIs Megento2 Rest Apis

For According to category use following url http://myfashionstore.com/rest/store2/V1/products?searchCriteria[pageSize]=10&searchCriteria[filterGroups][0][filters][0][field]=category_id&searchCriteria[filterGroups][0][filters][0][value]=6