Uni-App用uView组件库中u-picker实现地区的省-市-区三级联动、确认及回显

<u-form-item label="地区" :border-bottom="false">
    <u-cell :border="false">
       <view slot="right-icon" @tap="showLocal = true">
         <text :style="{ color: local.length ? '#333' : '#c0c4cc' }">{{ local === '' ? '选择省/市/区' : local }}</text>
       </view>
     </u-cell>
 </u-form-item>

 <u-picker
      @cancel="showLocal = false"
      @close="showLocal = false"
      :show="showLocal"
      :columns="addressColumns"
      @confirm="localConfirm"
      title="请选择所在地"
      keyName="name"
      itemHeight="80"
      closeOnClickOverlay
      ref="uPicker"
      @change="changeHandler"
      :defaultIndex="defaultAddress"
      immediateChange
    ></u-picker>

import areas from '@/utils/areas.json'//引入原始数据
  export default {
  data(){
	return {
			 local: '', //区域
			localCode: '', //这个变量看个人需求使用
	        showLocal: false,   //是否展示弹出层
	        addressColumns: [], //数据数组
	        defaultAddress: [],  //默认选中 (回填时或者初次显示默认选中)
	        addressData: areas,  //原始数据 (引入的json文件)
		}
	}    
}

   onShow() {
    //省的数组
      const provinceData = areas.map(e => {
        return { name: e.name, code: e.code }//这里可以直接return e.name  这里我是要用到code所以才用对象包起来的 下面的市 区 也一样
      })
//市的数组
      const cityData = areas.map(e => {
        const arr = []
        arr.push(
          e.areas.map(c => {
            return { name: c.name, code: c.code }
             
          })
        )
        return arr
      })
//区的数组
      const areaData = areas.map(e => {
        const arr = []
        arr.push(
          e.areas.map(c =>
            c.areas.map(d => {
              return { name: d.name, code: d.code }
            })
          )
        )
        return arr
      })
      const arr = [provinceData, cityData[0][0], areaData[0][0][0]]
      this.addressColumns = arr    //将得到的3个数组 的第一个市的所有数据赋值 作为初始数据
    
    },

 changeHandler(e) {
//分别表示选中的列 , 该列的第几个,选中的3列的第几个的数组,组件本身
        const { columnIndex, index, indexs, picker = this.$refs.uPicker } = e
       //如果改变的是第一列
        if (columnIndex === 0) {
          const children1 = this.addressData[index].areas.map(e => {
            return { name: e.name, code: e.code }
          })
          picker.setColumnValues(1, children1)
//更换 第二列数据
          const children2 = this.addressData[index].areas[indexs[1]].areas.map(e => {
            return { name: e.name, code: e.code }
          })
          picker.setColumnValues(2, children2)
//更换 第三列数据
        }
        if (columnIndex === 1) {
//如果改变的是第二列
          const children3 = this.addressData[indexs[0]].areas[indexs[1]].areas.map(e => {
            return { name: e.name, code: e.code }
          })
          picker.setColumnValues(2, children3)
//更换 第三列数据
        }
      },

    localConfirm(e) {
//显而易见 不多赘述
        this.local = `${e.value[0].name}-${e.value[1].name}-${e.value[2].name}`
        this.localCode = `${e.value[0].code}-${e.value[1].code}-${e.value[2].code}`
        this.showLocal = false

      },

//已经知道了 this.local ='省-市-区'初始弹窗时默认选中改值

     backfill(temp) {
        temp = item.area.split('-')
        let index,
          index1,
          index2 = 0
        let arr,
          arr1,
          arr2 = []
//匹配省市区对应每列的第几个
        this.addressData.forEach((item, i) => {
          if (item.name == temp[0]) {
            index = i
            item.children.forEach((val, ind) => {
              if (val.name == temp[1]) {
                index1 = ind
                val.children.forEach((e, n) => {
                  if (e.name == temp[2]) {
                    index2 = n
                  }
                })
              }
            })
          }
        })
        arr = this.addressData.map(e => {
          return { name: e.name, code: e.code }
        })
        arr1 = this.addressData[index].children.map(e => {
          return { name: e.name, code: e.code }
        })
        arr2 = this.addressData[index].children[index1].children.map(e => {
          return { name: e.name, code: e.code }
        })
//反推出3列的数组数据
        this.addressColumns = [arr, arr1, arr2]
// 赋值给 默认初始选中 
        this.defaultAddress = [index, index1, index2]
      }