PHPとUniAppでデータの多層連携を実現する方法

$provinceId = $_GET['province_id'];
$cities = $pdo->query("select * from cities where province_id = $provinceId")->fetchAll(PDO::FETCH_ASSOC);
echo json_encode($cities);

$cityId = $_GET['city_id'];
$areas = $pdo->query("select * from areas where city_id = $cityId")->fetchAll(PDO::FETCH_ASSOC);
echo json_encode($areas);

<view class="container">
    <picker mode="selector" range-key="name" range="{{provinces}}" bind:change="onChangeProvince">
        <view class="picker">
            {{province}}
        </view>
    </picker>
    
    <picker mode="selector" range-key="name" range="{{cities}}" bind:change="onChangeCity">
        <view class="picker">
            {{city}}
        </view>
    </picker>
    
    <picker mode="selector" range-key="name" range="{{areas}}">
        <view class="picker">
            {{area}}
        </view>
    </picker>
</view>

export default {
    data() {
        return {
            province: '',   // 省份
            city: '',       // 城市
            area: '',       // 区域
            provinces: [],  // 省份数据
            cities: [],     // 城市数据
            areas: []       // 区域数据
        }
    },
    mounted() {
        this.getProvinces()
    },
    methods: {
        // 获取省份数据
        getProvinces() {
            uni.request({
                url: 'http://localhost/getData.php',
                success: (res) => {
                    this.provinces = res.data
                }
            })
        },
        // 根据省份ID获取对应的城市数据
        getCities(provinceId) {
            uni.request({
                url: 'http://localhost/getData.php?province_id=' + provinceId,
                success: (res) => {
                    this.cities = res.data
                }
            })
        },
        // 根据城市ID获取对应的区域数据
        getAreas(cityId) {
            uni.request({
                url: 'http://localhost/getData.php?city_id=' + cityId,
                success: (res) => {
                    this.areas = res.data
                }
            })
        },
        // 省份选择器变化时的事件
        onChangeProvince(event) {
            const index = event.detail.value
            this.province = this.provinces[index].name
            this.city = ''
            this.area = ''
            this.getCities(this.provinces[index].id)
        },
        // 城市选择器变化时的事件
        onChangeCity(event) {
            const index = event.detail.value
            this.city = this.cities[index].name
            this.area = ''
            this.getAreas(this.cities[index].id)
        }
    }
}