how to add an admin form customer email dropdown in magento 2 code example

Example 1: how to add an admin form customer email dropdown in magento 2

<?php
namespace Webkul\Test\Ui\Component\Create\Form\Customer;
 
use Magento\Framework\Data\OptionSourceInterface;
use Magento\Customer\Model\ResourceModel\Customer\CollectionFactory as CustomerCollectionFactory;
use Magento\Framework\App\RequestInterface;
 
/**
 * Options tree for "Categories" field
 */
class Options implements OptionSourceInterface
{
    /**
     * @var \Magento\Customer\Model\ResourceModel\Customer\CollectionFactory
     */
    protected $customerCollectionFactory;
 
    /**
     * @var RequestInterface
     */
    protected $request;
 
    /**
     * @var array
     */
    protected $customerTree;
 
    /**
     * @param CustomerCollectionFactory $customerCollectionFactory
     * @param RequestInterface $request
     */
    public function __construct(
        CustomerCollectionFactory $customerCollectionFactory,
        RequestInterface $request
    ) {
        $this->customerCollectionFactory = $customerCollectionFactory;
        $this->request = $request;
    }
 
    /**
     * {@inheritdoc}
     */
    public function toOptionArray()
    {
        return $this->getCustomerTree();
    }
 
    /**
     * Retrieve categories tree
     *
     * @return array
     */
    protected function getCustomerTree()
    {
        if ($this->customerTree === null) {
            $collection = $this->customerCollectionFactory->create();
 
            $collection->addNameToSelect();
 
            foreach ($collection as $customer) {
                $customerId = $customer->getEntityId();
                if (!isset($customerById[$customerId])) {
                    $customerById[$customerId] = [
                        'value' => $customerId
                    ];
                }
                $customerById[$customerId]['label'] = $customer->getName();
            }
            $this->customerTree = $customerById;
        }
        return $this->customerTree;
    }
}

Example 2: how to add an admin form customer email dropdown in magento 2

define([
    'Magento_Ui/js/form/element/ui-select'
], function (Select) {
    'use strict';
    return Select.extend({
        /**
         * Parse data and set it to options.
         *
         * @param {Object} data - Response data object.
         * @returns {Object}
         */
        setParsed: function (data) {
            var option = this.parseData(data);
            if (data.error) {
                return this;
            }
            this.options([]);
            this.setOption(option);
            this.set('newOption', option);
        },
        /**
         * Normalize option object.
         *
         * @param {Object} data - Option object.
         * @returns {Object}
         */
        parseData: function (data) {
            return {
                value: data.customer.entity_id,
                label: data.customer.name
            };
        }
    });
});

Example 3: how to add an admin form customer email dropdown in magento 2

<field name="customer" component="Webkul_Test/js/components/select-customer" sortOrder="20" formElement="select">
    <argument name="data" xsi:type="array">
        <item name="config" xsi:type="array">
            <item name="filterOptions" xsi:type="boolean">true</item>//to add filter in select-ui
            <item name="multiple" xsi:type="boolean">false</item>//select multiple or not
            <item name="showCheckbox" xsi:type="boolean">true</item>
            <item name="disableLabel" xsi:type="boolean">true</item>
        </item>
    </argument>
    <settings>
        <required>true</required>
        <validation>
            <rule name="required-entry" xsi:type="boolean">true</rule>
        </validation>
        <elementTmpl>ui/grid/filters/elements/ui-select</elementTmpl>
        <label translate="true">Select Customer</label>//label to Field
        <dataScope>data.customer</dataScope>//To map
        <componentType>field</componentType>
        <listens>
            <link name="${ $.namespace }.${ $.namespace }:responseData">setParsed</link>
        </listens>
    </settings>
    <formElements>
        <select>
            <settings>
                <options class="Webkul\Test\Ui\Component\Create\Form\Customer\Options"/>
            </settings>
        </select>
    </formElements>
</field>