Vant picker 实现多级联动的方法

<van-field readonly clickable placeholder="选择城市" :value="station" @click="showPicker = true" />

<van-popup v-model="showPicker" position="bottom">
<van-picker show-toolbar :columns="columns" @cancel="showPicker = false" @confirm="onConfirm" @change="onChange" />
</van-popup>

const citys = [ // 我们习惯的格式。 可以后台给你出，如果你打不过的话，你就。。。
 {
  text: "测试一", // 默认识别text标签
  id: 1,
  children: [
   {
    id: 11,
    text: "测试1-1",
    children: [
     {
      id: 111,
      text: "测试1-1-1"
     },
     {
      id: 112,
      text: "测试1-1-2"
     }
    ]
   },
   {
    id: 12,
    text: "测试1-2",
    children: [
     {
      id: 122,
      text: "测试1-2-1"
     },
     {
      id: 122,
      text: "测试1-2-2"
     }
    ]
   },
   {
    id: 13,
    text: "测试1-3"
   }
  ]
 },
 {
  text: "测试二",
  id: 2,
  children: [
   {
    id: 21,
    text: "测试2",
    children: [
     {
      id: 221,
      text: "测试2-2-1"
     },
     {
      id: 222,
      text: "测试2-2-2"
     }
    ]
   },
   {
    id: 22,
    text: "测试2"
   },
   {
    id: 23,
    text: "测试2"
   }
  ]
 },
 {
  text: "测试三",
  id: 3,
  children: [
   {
    id: 31,
    text: "测试3",
    children: [
     {
      id: 311,
      text: "测试3-1-1"
     },
     {
      id: 312,
      text: "测试3-3-2"
     }
    ]
   },
   {
    id: 32,
    text: "测试3"
   },
   {
    id: 33,
    text: "测试3"
   }
  ]
 }
];

 data(){
  return {
   station: "",
   showPicker: false,
   columns: [
    {
     values: citys, // 设置的页面初始值
     className: "column1"
    },
    {
     values: citys[0].children,
     className: "column2"
    },
    {
     values: citys[0].children[0].children,
     className: "column3"
    }
   ],
 } 
 }; 

  onConfirm(value) {
   const compact = arr => arr.filter(Boolean); // 三级联动 去除没值的，比如只有两级
   const result = compact(value);
   let str = ""; // 呈现页面显示 /xxx/xxx/xxx
   result.forEach(item => {
    str += "/" + item.text;
   });
   this.station = str;
   this.showPicker = false;
   
  const end = result[result.length - 1]; // 一般都是取最后一个id给后台的
   const id = end.id;
   console.log(id);
  },
  onChange(picker, values, index) { // 实在不行自己打印测试
   if (index == 0) {
    picker.setColumnValues(2, []); // 防止突然选中第一个，第二个是更新的，但第三个联级不更新，我暂时强制清空
   }
   let ColumnIndex = picker.getColumnIndex(index);
   console.log("第" + index + "列", "第" + ColumnIndex + "个");
   picker.setColumnValues(index + 1, values[ColumnIndex ].children || []);//点当前列更新下一列数据，防止undefined 
   
 // 当然，如果后台数据不给你想要的格式，你就按需请求一次了，比如选中第一个，取id请求接口，更新下一列。毕竟连动内容多的话，页面请求也多。但页面就不流畅，比如第一列第二列初始值。 
  // 我就是打不过后台。。。
  }

<!-- 选择 收支类型弹窗 -->
<van-popup ref = "accountTypePopup" v-model="showPicker" position="bottom">
  <van-picker
    ref = "accountTypePopup2"
    show-toolbar
    :columns="columns"
    @cancel="showPicker = false"
    @confirm="onConfirm"
    @change="onChange"
    
  />
</van-popup>
methods: {
  // ...
  // 修改 columns 方法
  changeColumns(p_name, name) {
    // p_name 一级分类回显值
    // name 二级分类回显值
    
    // 类型列表
    var typeList =
      this.tabActive === 0
        &#63; this.expendTypeList
        : this.incomeTypeList;
 
    // 设置 收支类型选项 columns 的默认值 和 子选项
    this.columns[0]["defaultIndex"] = this.columns[0][
      "values"
    ].findIndex(item => item === p_name);
 
    this.columns[1]["values"] = typeList[p_name];
 
    this.columns[1]["defaultIndex"] = this.columns[1][
      "values"
    ].findIndex(item => item === name);
  }
}

<!-- 选择 收支类型弹窗 -->
<van-popup ref = "accountTypePopup" v-model="showPicker" position="bottom">
  <van-picker
    ref = "accountTypePopup2"
    show-toolbar
    :columns="columns"
    @cancel="showPicker = false"
    @confirm="onConfirm"
    @change="onChange"
 
    // 这里是新加的 //
    :key = "account_type_value"
    
  />
</van-popup>