<template>
    <div class="ui-wrap">
        <el-tree
            :data="data"
            show-checkbox
            node-key="id"
            :default-expanded-keys="[2, 3]"
            :default-checked-keys="[5]"
            :props="defaultProps">
        </el-tree>
    </div>
</template>

<script>
export default {
  data() {
    return {
      data: [{
        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="scss">
.ui-wrap > div {
  margin-bottom: 10px;
  margin-top: 20px;
}
.el-form-item__content {
  margin-left: 0 !important;
}
.el-select .el-input {
  width: 100px;
}
.input-with-select .el-input-group__prepend {
  background-color: #fff;
}
</style>