vue elementui admin 中打開el-dialog彈窗組件時重新渲染的問題

父組件代碼，key傳入不同的值會使組件重新渲染，不會留下之前填寫過的內容

<template>
  <el-form-item>
      <el-button type="primary" @click="addOrUpdateHandle()">新增</el-button>
  </el-form-item>
  <!-- 子組件：彈窗, 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會使組件重新渲染
      this.addOrUpdateKey++
      this.addOrUpdateVisible = true
    }
  },
  components: {
    AddOrUpdate,
  }
}
</script>