vue elementui admin 中打开el-dialog弹窗组件时重新渲染的问题

父组件代码，key传入不同的值会使组件重新渲染，不会留下之前填写过的内容

<template>
  <el-form-item>
      <el-button type="primary" @click="addOrUpdateHandle()">新增</el-button>
  </el-form-item>
  <!-- 子组件：弹窗, 新增 / 修改 -->
  <add-or-update v-if="addOrUpdateVisible" :key="addOrUpdateKey" ref="addOrUpdate" ></add-or-update>
</template>

<script>
import AddOrUpdate from './trainingplan-add-or-update'
export default {
  data () {
    return {
      addOrUpdateVisible: false,
      addOrUpdateKey: 0
    }
  },
  methods: {
    addOrUpdateHandle () {
      //key每次加1会使组件重新渲染
      this.addOrUpdateKey++
      this.addOrUpdateVisible = true
    }
  },
  components: {
    AddOrUpdate,
  }
}
</script>