vue中下拉框如何显示树形结构

原理:其实就是利用<el-tree>插件与<Input>插件模拟一个树形结构的下拉框 重点在样式代码

代码:

<template>
  <label class="select-tree" @click="showTree = true">
    <el-input v-model="inputVal" placeholder="请下拉选择树形结构数据"/>
    <el-collapse-transition>
      <div class="tree-modal" v-show="showTree" @mouseleave="showTree = false">
        <el-tree :data="filterList" ref="selectTreeData" node-key="id" show-checkbox/>
        <div class="popper-arrow" style="left: 35px;"></div>
      </div>
    </el-collapse-transition>
  </label>
</template>

<script>
  export default {
    name: "test",
    data() {
      return {
        inputVal:"",
        showTree:false,
        filterList: [{
          id: 1,
          label: 一级 1,
          children: [{
            id: 4,
            label: 二级 1-1,
            children: [{
              id: 9,
              label: 三级 1-1-1
            }, {
              id: 10,
              label: 三级 1-1-2
            }]
          }]
        }, {
          id: 2,
          label: 一级 2,
          children: [{
            id: 5,
            label: 二级 2-1
          }, {
            id: 6,
            label: 二级 2-2
          }]
        }, {
          id: 3,
          label: 一级 3,
          children: [{
            id: 7,
            label: 二级 3-1
          }, {
            id: 8,
            label: 二级 3-2
          }]
        }],
        defaultProps: {
          children: children,
          label: label
        }
      };
    }
  }
</script>

<style lang="less">
  .select-tree {
    flex: 1;
    margin-right: 10px;
    max-width: 300px;
    height: 30px;
    background: #FFFFFF;
    line-height: 30px;
    .el-input__inner{
      height: 30px;
      border-radius: 1px;
      line-height: 30px;
    }
    .tree-modal{
      position: absolute;
      max-width: 300px;
      overflow:auto;
      z-index: 888;
      box-shadow: 0 2px 12px 0 rgba(0, 0, 0, 0.5);
      margin-top: 10px;
      .el-tree {
        width: auto;
        max-height: 300px;
        z-index: 999;
        padding-right: 10px;
        padding-bottom: 10px;
        overflow: auto;
        min-width: 200px;
        max-width: inherit;
        margin-top: 5px;
      }

      .el-tree--highlight-current .el-tree-node.is-current > .el-tree-node__content {
        background-color: rgba(87, 163, 243, 0.8);
        color: #FFFFFF;
      }
      .popper-arrow {
        top: 28px;
        margin-right: 3px;
        border-top-width: 0;
        position: absolute;
        border-width: 6px;
        border-color: #FFFFFF;
        animation: mymove 2s;
        opacity: 1
      }
      @keyframes mymove {
        0% {
          opacity: 0
        }
        100% {
          opacity: 1
        }
      }
      .popper-arrow::after {
        content: "";
        position: absolute;
        display: block;
        width: 0;
        height: 0;
        border-color: transparent;
        border-style: solid;
        top: 1px;
        margin-left: -6px;
        border-top-width: 0;
        border-bottom-color: #FFFFFF;
        border-width: 6px;
      }
    }
  }
</style>