How to set value of Customer Custom attribute in Magento 2.0.x

Here we will learn, How to set value of Customer Custom attribute in Magento 2.0.x

Using Controller file to set the value.

<?php

namespace Webkul\CustomerAttribute\Controller\Account;

use Magento\Framework\App\Action\Context;
use Magento\Framework\Data\Form\FormKey\Validator as FormKeyValidator;
use Magento\Framework\View\Result\PageFactory;
use Magento\Customer\Api\CustomerRepositoryInterface;
use Magento\Customer\Api\Data\CustomerInterfaceFactory;
use Magento\Framework\App\RequestInterface;
use Magento\Framework\Api\DataObjectHelper;

class SavePrice extends \Magento\Customer\Controller\AbstractAccount
{
    /**
     * @var \Magento\Customer\Model\Session
     */
    protected $_customerSession;

    /**
     * @var \Magento\Framework\Data\Form\FormKey\Validator
     */
    protected $_formKeyValidator;

    /** @var CustomerRepositoryInterface */
    protected $_customerRepository;
    /**
     * @var \Magento\Customer\Model\Customer\Mapper
     */
    protected $_customerMapper;
    /**
     * @var CustomerInterfaceFactory
     */
    protected $_customerDataFactory;
    /**
     * @var DataObjectHelper
     */
    protected $_dataObjectHelper;

    /**
     * @param Context $context
     * @param Session $customerSession
     * @param FormKeyValidator $formKeyValidator
     * @param PageFactory $resultPageFactory
     * @SuppressWarnings(PHPMD.ExcessiveParameterList)
     */
    public function __construct(
        Context $context,
        Session $customerSession,
        FormKeyValidator $formKeyValidator,
        CustomerRepositoryInterface $customerRepository,
        CustomerInterfaceFactory $customerDataFactory,
        DataObjectHelper $dataObjectHelper,
        \Magento\Customer\Model\Customer\Mapper $customerMapper,
        PageFactory $resultPageFactory
    ) {
        $this->_customerSession = $customerSession;
        $this->_customerRepository = $customerRepository;
        $this->_customerMapper = $customerMapper;
        $this->_customerDataFactory = $customerDataFactory;
        $this->_dataObjectHelper = $dataObjectHelper;
        $this->_formKeyValidator = $formKeyValidator;
        parent::__construct(
            $context,
            $customerSession,
            $formKeyValidator,
            $resultPageFactory
        );
    }

    /**
     * Retrieve customer session object
     *
     * @return \Magento\Customer\Model\Session
     */
    protected function _getSession()
    {
        return $this->_customerSession;
    }

    /**
     * Check customer authentication
     *
     * @param RequestInterface $request
     * @return \Magento\Framework\App\ResponseInterface
     */
    public function dispatch(RequestInterface $request)
    {
        $loginUrl = $this->_objectManager->get('Magento\Customer\Model\Url')->getLoginUrl();

        if (!$this->_customerSession->authenticate($loginUrl)) {
            $this->_actionFlag->set('', self::FLAG_NO_DISPATCH, true);
        }
        return parent::dispatch($request);
    }   

    /**
     * Default customer account page
     *
     * @return \Magento\Framework\View\Result\Page
     */
    public function execute()
    {
        /** @var \Magento\Framework\Controller\Result\Redirect $resultRedirect */
        $resultRedirect = $this->resultRedirectFactory->create();

        if ($this->getRequest()->isPost()) {
            if (!$this->_formKeyValidator->validate($this->getRequest())) {
                return $this->resultRedirectFactory
                        ->create()
                        ->setPath('*/*/index', ['_secure'=>$this->getRequest()->isSecure()]);
            }
            $customerData = $this->getRequest()->getParams(); //get attributes value from form            
            $customerId=$this->_getSession()->getCustomerId();
            // get customer saved data 
            $savedCustomerData = $this->_customerRepository->getById($customerId);
            $customer = $this->_customerDataFactory->create();
            //merge saved customer data with new values
            $customerData = array_merge(
                $this->_customerMapper->toFlatArray($savedCustomerData),
                $customerData
            );
            $customerData['id'] = $customerId;
            $this->_dataObjectHelper->populateWithArray(
                $customer,
                $customerData,
                '\Magento\Customer\Api\Data\CustomerInterface'
            );
            //save customer
            $this->_customerRepository->save($customer);
            $this->messageManager->addSuccess(__('Value has been successfully saved'));
            return $this->resultRedirectFactory->create()->setPath('path', ['_secure'=>$this->getRequest()->isSecure()]);
        }            
    }
}

By using the same approach you can set the value for customer’s custom attribute.