1、xml代码：

<?xml version="1.0" encoding="UTF-8"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
    <argument name="data" xsi:type="array">
        <item name="js_config" xsi:type="array">
            <item name="provider" xsi:type="string">upsell_rule_form.rule_form_data_source</item>
            <item name="deps" xsi:type="string">upsell_rule_form.rule_form_data_source</item>
        </item>
        <item name="layout" xsi:type="array">
            <item name="type" xsi:type="string">tabs</item>
        </item>
        <item name="buttons" xsi:type="array">
            <item name="save" xsi:type="array">
                <item name="name" xsi:type="string">save</item>
                <item name="label" xsi:type="string" translate="true">保存 Rule</item>
                <item name="class" xsi:type="string">primary</item>
                <item name="url" xsi:type="string">upsell/rule/save</item>
            </item>
            <item name="back" xsi:type="array">
                <item name="name" xsi:type="string">back</item>
                <item name="label" xsi:type="string" translate="true">返回</item>
                <item name="class" xsi:type="string">back</item>
                <item name="url" xsi:type="string">upsell/rule/listing</item>
            </item>
        </item>
    </argument>
    <settings>
        <namespace>upsell_rule_form</namespace>
    </settings>
    <dataSource name="rule_form_data_source">
        <argument name="data" xsi:type="array">
            <item name="js_config" xsi:type="array">
                <item name="component" xsi:type="string">Magento_Ui/js/form/provider</item>
            </item>
        </argument>
        <settings>
            <submitUrl path="upsell/rule/save"/>
        </settings>
        <dataProvider class="Aiweline\Upsell\Model\ResourceModel\UpsellRule\DataProvider" name="rule_form_data_source">
            <settings>
                <requestFieldName>rule_id</requestFieldName>
                <primaryFieldName>rule_id</primaryFieldName>
            </settings>
        </dataProvider>
    </dataSource>
    <fieldset name="general">
        <settings>
            <label translate="true">Rule信息</label>
            <collapsible>false</collapsible>
        </settings>
        <field name="rule_id" formElement="hidden">
            <argument name="data" xsi:type="array">
                <item name="config" xsi:type="array">
                    <item name="source" xsi:type="string">rule</item>
                    <item name="label" xsi:type="string" translate="true">Rule ID</item>
                </item>
            </argument>
            <settings>
                <dataType>text</dataType>
            </settings>
        </field>
        <field name="name" formElement="input">
            <argument name="data" xsi:type="array">
                <item name="config" xsi:type="array">
                    <item name="source" xsi:type="string">rule</item>
                    <item name="label" xsi:type="string" translate="true">Rule名称</item>
                </item>
            </argument>
            <settings>
                <validation>
                    <rule name="required-entry" xsi:type="boolean">true</rule>
                </validation>
                <dataType>text</dataType>
            </settings>
        </field>
        <field name="is_active" formElement="checkbox">
            <settings>
                <label translate="true">启用状态</label>
                <tooltip>
                    <description translate="true">启用则生效，不启用则不生效！</description>
                </tooltip>
                <validation>
                    <rule name="required-entry" xsi:type="boolean">true</rule>
                </validation>
            </settings>
            <formElements>
                <checkbox>
                    <settings>
                        <prefer>toggle</prefer>
                        <valueMap>
                            <map name="false" xsi:type="string">0</map>
                            <map name="true" xsi:type="string">1</map>
                        </valueMap>
                    </settings>
                </checkbox>
            </formElements>
        </field>
        <field name="store_code" formElement="select">
            <argument name="data" xsi:type="array">
                <item name="config" xsi:type="array">
                    <item name="source" xsi:type="string">rule</item>
                    <item name="dataType" xsi:type="string">text</item>
                    <item name="visibleValue" xsi:type="string">1</item>
                </item>
            </argument>
            <settings>
                <dataType>text</dataType>
                <label translate="true">选择关联店铺</label>
                <validation>
                    <rule name="required-entry" xsi:type="boolean">true</rule>
                </validation>
            </settings>
            <formElements>
                <select>
                    <settings>
                        <options class="Aiweline\Core\Model\M24\Config\Source\Stores"/>
                    </settings>
                </select>
            </formElements>
        </field>
        <field name="type" formElement="select">
            <argument name="data" xsi:type="array">
                <item name="config" xsi:type="array">
                    <item name="source" xsi:type="string">rule</item>
                    <item name="visibleValue" xsi:type="string">1</item>
                </item>
            </argument>
            <settings>
                <validation>
                    <rule name="required-entry" xsi:type="boolean">true</rule>
                </validation>
                <dataType>text</dataType>
                <label translate="true">优惠类型</label>
            </settings>
            <formElements>
                <select>
                    <settings>
                        <options class="Aiweline\Upsell\Model\Config\Source\TypeOption"/>
                    </settings>
                </select>
            </formElements>
        </field>
        <field name="value" formElement="input">
            <argument name="data" xsi:type="array">
                <item name="config" xsi:type="array">
                    <item name="source" xsi:type="string">rule</item>
                    <item name="label" xsi:type="string" translate="true">值</item>
                </item>
            </argument>
            <settings>
                <validation>
                    <rule name="required-entry" xsi:type="boolean">true</rule>
                    <rule name="max_text_length" xsi:type="string">60</rule>
                </validation>
                <dataType>text</dataType>
            </settings>
        </field>
    </fieldset>
</form>

2、DataProvider

提示：这是Magento的xml编译时的数据提供器，这个的作用主要是修改提供器提供的字段信息使用的，很有用，也很重要。

<?php
/**
 * 文件信息
 * 作者：邹万才
 * 網名：秋风雁飞(可以百度看看)
 * 網站：www.aiweline.com/bbs.aiweline.com
 * 工具：PhpStorm
 * 日期：2020-2-23
 * 时间：下午 02:06
 * 描述：
 */
namespace Aiweline\Upsell\Model\ResourceModel\UpsellRule;
use Magento\Framework\Exception\NoSuchEntityException;
use Aiweline\Upsell\Model\ResourceModel\UpsellRule\CollectionFactory as RuleCollectionFactory;
class DataProvider extends \Magento\Ui\DataProvider\AbstractDataProvider
{
    protected $request;
    protected $loadedData;
    protected $storeManager;
    private \Aiweline\Upsell\Model\UpsellRuleFactory $ruleFactory;
    public function __construct(
        RuleCollectionFactory $ruleCollectionFactory,
        \Magento\Framework\App\RequestInterface $request,
        \Aiweline\Upsell\Model\UpsellRuleFactory $ruleFactory,
        \Magento\Store\Model\StoreManagerInterface $storeManager,
        $name,
        $primaryFieldName,
        $requestFieldName,
        array $meta = [],
        array $data = []
    )
    {
        $this->collection = $ruleCollectionFactory->create();
        $this->ruleFactory = $ruleFactory;
        $this->request = $request;
        $this->storeManager = $storeManager;
        parent::__construct($name, $primaryFieldName, $requestFieldName, $meta, $data);
    }
    public function getData()
    {
        // 读取ID,检查是更新还是新增
        $requestId = $this->request->getParam($this->requestFieldName);
        if (isset($this->loadedData)) {
            return $this->loadedData;
        }
        $rule = $this->ruleFactory->create();
        // 如果是 update 操作
        if ($requestId) {
            $rule->load($requestId);
            if (!$rule->getId()) {
                throw NoSuchEntityException::singleField('id', $requestId);
            }
            //设置UpsellRule预览图:
            $baseUrl = $this->storeManager->getStore()->getBaseUrl();
            $ruleImage[] = ['url'=>$baseUrl . $rule->getData('rule')];
            $rule->setData('rule',$ruleImage);
            // 设置分类回填
            $ruleData = $rule->getData();
            $this->loadedData[$requestId]['general'] = $ruleData;
        } else {
            // new 操作
            $this->loadedData = [];
        }
        return $this->loadedData;
    }
}