Magento 2: Model edit form fields not loading

Question

I've created a grid for my "profile" model. Add and delete works fine, but when I click on the "Edit" action, the resulting page doesn't load the profile's existing fields.

I understand that we pull from the model storage when editing, which is working, but how do we populate the edit form with existing fields? Here's my Edit class.

<?php
namespace mycompany\mymodule\Controller\Adminhtml\Profile;

class Edit extends \Magento\Backend\App\Action
{
    /**
    * @var \Magento\Framework\View\Result\PageFactory
    */
    protected $_resultPageFactory;

    /**
    * @var \mycompany\mymodule\Model\Profile\ProfileFactory
    */
    protected $_profileFactory;

    /**
    * @var \Magento\Framework\Registry
    */
    protected $_coreRegistry;

    /**
    * @var \Magento\Backend\Model\Session
    */
    protected $_backendSession;

    public function __construct(
        \Magento\Backend\App\Action\Context $context,
        \Magento\Framework\View\Result\PageFactory $resultPageFactory,
        \Magento\Framework\Registry $coreRegistry,
        \mycompany\mymodule\Model\Profile\ProfileFactory $profileFactory
    ) {
        parent::__construct($context);
        $this->_resultPageFactory = $resultPageFactory;
        $this->_coreRegistry = $coreRegistry;
        $this->_backendSession = $this->_getSession();
        $this->_profileFactory = $profileFactory;
    }

    /**
    * @return \Magento\Framework\View\Result\Page
    */
    public function execute()
    {
        $id = $this->getRequest()->getParam('id');
        $profile = $this->_initProfile();
        $resultPage = $this->_resultPageFactory->create();
        $resultPage->getConfig()->getTitle()->set(__('Profiles'));
        if ($id) {
            $profile->load($id);
            if (!$profile->getId()) {
                $this->messageManager->addError(__('This profile no longer exists.'));
                $resultRedirect = $this->_resultRedirectFactory->create();
                $resultRedirect->setPath(
                    'myroute/profile/profiles',
                    [
                        'profile_id' => $profile->getId(),
                        '_current' => true
                    ]
                );
                return $resultRedirect;
            }
        }
        $title = $profile->getId() ? $profile->getName() : __('New Profile');
        $resultPage->getConfig()->getTitle()->prepend($title);
        $data = $this->_backendSession->getData('profile_form', true);
        if (!empty($data)) {
            $profile->setData($data);
        }
        return $resultPage;
    }

    /**
     * Init Profile
     *
     * @return \mycompany\mymodule\Model\Profile
     */
    protected function _initProfile()
    {
        $profileId = (int) $this->getRequest()->getParam('id');
        $profile = $this->_profileFactory->create();
        if ($profileId) {
            $profile->load($profileId);
        }
        $this->_coreRegistry->register('mymodule_profile', $profile);
        return $profile;
    }
}

Answer 1

Turns out I needed a data provider for my profile model class. Here's my getData() function.

/**
     * Get data
     *
     * @return array
     */
    public function getData()
    {
        if (isset($this->loadedData)) {
            return $this->loadedData;
        }
        $items = $this->collection->getItems();
        /** @var Rule $rule */
        foreach ($items as $rule) {
            $rule->load($rule->getId());
            $this->loadedData[$rule->getId()] = $rule->getData();
        }
        if (empty($this->loadedData)) {
            $this->loadedData = [];
        }

        $data = $this->_dataPersistor->get('profile');
        if (!empty($data)) {
            $rule = $this->collection->getNewEmptyItem();
            $rule->setData($data);
            $this->loadedData[$rule->getId()] = $rule->getData();
            $this->_dataPersistor->clear('profile');
        }
    return $this->loadedData;
    }