add categories tree to customer eav attribute

Question

I'm trying to create an EAV attribute for the customer, and I need the input to be the product categories tree like the following image: Is this acheivable? And how? please.

Answer 1

You can reuse some Catalog resources and you need to define custom Source Model

1. Source Model

app/code/Acme/StackExchange/Model/Source/CategoriesTree.php

<?php
declare(strict_types=1);

namespace Acme\StackExchange\Model\Source;

use Magento\Backend\Model\Auth\Session;
use Magento\Catalog\Model\Category as CategoryModel;
use Magento\Catalog\Model\Locator\LocatorInterface;
use Magento\Catalog\Model\ResourceModel\Category\CollectionFactory as CategoryCollectionFactory;
use Magento\Framework\App\CacheInterface;
use Magento\Framework\Data\OptionSourceInterface;
use Magento\Framework\DB\Helper as DbHelper;
use Magento\Framework\Exception\LocalizedException;
use Magento\Framework\Serialize\SerializerInterface;

class CategoriesTree implements OptionSourceInterface
{
    private const CATEGORY_TREE_ID = 'CATALOG_PRODUCT_CATEGORY_TREE';

    protected LocatorInterface          $locator;
    protected CategoryCollectionFactory $categoryCollectionFactory;
    protected DbHelper                  $dbHelper;
    protected CacheInterface            $cache;
    protected SerializerInterface       $serializer;
    protected Session                   $session;

    public function __construct(
        LocatorInterface $locator,
        CategoryCollectionFactory $categoryCollectionFactory,
        DbHelper $dbHelper,
        CacheInterface $cache,
        SerializerInterface $serializer,
        Session $session
    ) {
        $this->locator                   = $locator;
        $this->categoryCollectionFactory = $categoryCollectionFactory;
        $this->dbHelper                  = $dbHelper;
        $this->cache                     = $cache;
        $this->serializer                = $serializer;
        $this->session                   = $session;
    }

    /**
     * @inheritDoc
     */
    public function toOptionArray()
    {
        $storeId = (int)$this->locator->getStore()->getId();

        $cachedCategoriesTree = $this->cache->load($this->getCategoriesTreeCacheId($storeId, ''));
        if (!empty($cachedCategoriesTree)) {
            return $this->serializer->unserialize($cachedCategoriesTree);
        }

        $categoriesTree = $this->retrieveCategoriesTree(
            $storeId,
            $this->retrieveShownCategoriesIds($storeId, '')
        );

        $this->cache->save(
            $this->serializer->serialize($categoriesTree),
            $this->getCategoriesTreeCacheId($storeId, ''),
            [
                \Magento\Catalog\Model\Category::CACHE_TAG,
                \Magento\Framework\App\Cache\Type\Block::CACHE_TAG,
            ]
        );

        return $categoriesTree;
    }

    /**
     * Get cache id for categories tree.
     *
     * @param int $storeId
     * @param string $filter
     * @return string
     */
    private function getCategoriesTreeCacheId(int $storeId, string $filter = ''): string
    {
        if ($this->session->getUser() !== null) {
            return self::CATEGORY_TREE_ID
                . '_' . (string)$storeId
                . '_' . $this->session->getUser()->getAclRole()
                . '_' . $filter;
        }
        return self::CATEGORY_TREE_ID
            . '_' . (string)$storeId
            . '_' . $filter;
    }

    /**
     * Retrieve tree of categories with attributes.
     *
     * @param int $storeId
     * @param array $shownCategoriesIds
     * @return array|null
     * @throws LocalizedException
     */
    private function retrieveCategoriesTree(int $storeId, array $shownCategoriesIds): ?array
    {
        $collection = $this->categoryCollectionFactory->create();

        $collection->addAttributeToFilter('entity_id', ['in' => array_keys($shownCategoriesIds)])
            ->addAttributeToSelect(['name', 'is_active', 'parent_id'])
            ->setStoreId($storeId);

        $categoryById = [
            CategoryModel::TREE_ROOT_ID => [
                'value'    => CategoryModel::TREE_ROOT_ID,
                'optgroup' => null,
            ],
        ];

        foreach ($collection as $category) {
            foreach ([$category->getId(), $category->getParentId()] as $categoryId) {
                if (!isset($categoryById[$categoryId])) {
                    $categoryById[$categoryId] = ['value' => $categoryId];
                }
            }

            $categoryById[$category->getId()]['is_active']        = $category->getIsActive();
            $categoryById[$category->getId()]['label']            = $category->getName();
            $categoryById[$category->getId()]['__disableTmpl']    = true;
            $categoryById[$category->getParentId()]['optgroup'][] = &$categoryById[$category->getId()];
        }

        return $categoryById[CategoryModel::TREE_ROOT_ID]['optgroup'];
    }

    /**
     * Retrieve filtered list of categories id.
     *
     * @param int $storeId
     * @param string $filter
     * @return array
     * @throws LocalizedException
     */
    private function retrieveShownCategoriesIds(int $storeId, string $filter = ''): array
    {
        $matchingNamesCollection = $this->categoryCollectionFactory->create();

        if (!empty($filter)) {
            $matchingNamesCollection->addAttributeToFilter(
                'name',
                ['like' => $this->dbHelper->addLikeEscape($filter, ['position' => 'any'])]
            );
        }

        $matchingNamesCollection->addAttributeToSelect('path')
            ->addAttributeToFilter('entity_id', ['neq' => CategoryModel::TREE_ROOT_ID])
            ->setStoreId($storeId);

        $shownCategoriesIds = [];

        foreach ($matchingNamesCollection as $category) {
            foreach (explode('/', $category->getPath()) as $parentId) {
                $shownCategoriesIds[$parentId] = 1;
            }
        }

        return $shownCategoriesIds;
    }
}

2. Define field in form

app/code/Acme/StackExchange/view/adminhtml/ui_component/customer_form.xml

<?xml version="1.0" encoding="UTF-8"?>
<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
    <fieldset name="customer">
        <container name="container_category_ids" sortOrder="400">
            <argument name="data" xsi:type="array">
                <item name="config" xsi:type="array">
                    <item name="formElement" xsi:type="string">container</item>
                    <item name="componentType" xsi:type="string">container</item>
                    <item name="component" xsi:type="string">Magento_Ui/js/form/components/group</item>
                    <item name="label" translate="true" xsi:type="string">Categories</item>
                    <item name="required" xsi:type="boolean">false</item>
                </item>
            </argument>
            <field name="category_ids" formElement="select" component="Magento_Catalog/js/components/new-category">
                <argument name="data" xsi:type="array">
                    <item name="config" xsi:type="array">
                        <item name="filterOptions" xsi:type="boolean">true</item>
                        <item name="chipsEnabled" xsi:type="boolean">true</item>
                        <item name="disableLabel" xsi:type="boolean">true</item>
                        <item name="elementTmpl" xsi:type="string">ui/grid/filters/elements/ui-select</item>
                        <item name="levelsVisibility" xsi:type="string">1</item>
                        <item name="componentType" xsi:type="string">field</item>
                        <item name="config" xsi:type="array">
                            <item name="dataScope" xsi:type="string">category_ids</item>
                            <item name="sortOrder" xsi:type="string">10</item>
                        </item>
                    </item>
                </argument>
                <formElements>
                    <select>
                        <settings>
                            <options class="Acme\StackExchange\Model\Source\CategoriesTree"/>
                        </settings>
                    </select>
                </formElements>
            </field>
        </container>
    </fieldset>
</form>