处理父组件方法更新到子组件无法渲染

这次给大家带来处理父组件方法更新到子组件无法渲染，处理父组件方法更新到子组件无法渲染的注意事项有哪些，下面就是实战案例，一起来看一下。

场景：

我实际用到的是这样的，我父组件引用子组件related,父组件调用获取页面详情的方法，更新了state值related，子组件根据该related来渲染相关新闻内容，但是页面打开的时候总是先加载子组件，子组件在渲染的时候还没有获取到更新之后的related值，即使在子组件中watch该值的变化依然不能渲染出来子组件的相关新闻内容。

我的解决办法：

父组件像子组件传值，当父组件执行了获取页面详情的方法之后，state值related更新，然后传给子组件，子组件再进行渲染，可以正常获取到。

父组件代码：

<template>
 <p id="newsDetails">
  <mt-header title="详情">
   <router-link to="/" slot="left">
    <mt-button icon="back"></mt-button>
   </router-link>
  </mt-header>
  <p class="details clearfloat">
   <h1 class="titleFont">
    {{ title }}
   </h1>
   <p class="clearfloat sourceWrap">
    <ul class="sourceFont">
     <li v-if="(pubNews==true)">
      <span class="source">{{pubName}}</span>
     </li>
     <li>
      <span class="authorName">{{authorName}}</span>
      <span class="time">{{createAt|formatTime}}</span>
     </li>
    </ul>
    <span v-if="(pubNews==true)" class='btnFollow' @click="follow">关注</span>
   </p>
   <p class="bodyFont clearfloat" id="bodyFont" ref="bodyFont" :class="{bodyHeight:contentStatus}">
    <p v-html="content"></p>
    <p class="editor" v-if="editorName">责任编辑：{{editorName}}</p>
   </p>
   <p class="contentToggle" @click="contentStatus=!contentStatus" v-if="contentStatus">阅读全文</p>
   <Related :related="related"></Related>
　　　　<!--重点是这里 父组件向子组件传值-->
 </p> </p> </template>
import { Toast } from 'mint-ui';
 import {mapState} from 'vuex'
 import Related from './Related.vue'
 import moment from 'moment';
 export default{
  name:"NewsDetails",
  components:{
   Related,
  },
  data(){
   return {
    id:this.$route.params.id,
    topicType:"news",
    contentStatus:false,
    curHeight:0,
    bodyHeight:5000,
    hotCommentScrollTop:0
   }
  },
  created(){
   this.id=this.$route.params.id;
   this.fetchData();
   moment.locale('zh-cn');
  },
  mounted(){
   setTimeout(()=>{
    this.contentToggle();
   },500)
  },
  watch: {
   '$route'(to,from){
    this.id=this.$route.params.id;
    this.fetchData();
   }
  },
  computed: {
   ...mapState({
    title: state => state.newsDetails.title,
    authorName: state => state.newsDetails.authorName,
    pubNews: state => state.newsDetails.pubNews,
    pubName: state => state.newsDetails.pubName,
    editorName: state => state.newsDetails.editorName,
    createAt: state => state.newsDetails.createAt,
    content: state => state.newsDetails.content,
    myFavourite: state => state.newsDetails.myFavourite,
    related: state => state.newsDetails.related,
   })
  },
  filters:{
   formatTime(time){
    return moment(time).fromNow();
   },
  },
  methods:{
   fetchData(){
    this.$store.dispatch('getDetails',this.id);
   },
   follow(){
    Toast('登录后进行关注');
    this.$router.push("/login");
   },
   contentToggle(){
    this.curHeight=this.$refs.bodyFont.offsetHeight;
    if(parseFloat(this.curHeight)>parseFloat(this.bodyHeight)){
     this.contentStatus=true;
    }else{
     this.contentStatus=false;
    }
//    this.hotCommentScrollTop=this.$refs.hotComment.height;
    console.log(this.hotCommentScrollTop);
   },
  }
 }

子组件related.vue

<template>
  <p v-if="lists.length>0">
    <p class="tagTitle"><span>相关新闻</span></p>
    <p class="listItem" v-if="(item.type=='little')" v-for="(item,index) in lists" :to="{name:'details',params:{id:item.id}}" :key="index" @click="browserDetection()">
     <p class="listImg1">
      <!--<img :src="{lazy==loaded?item.thumb[0]:lazy==loading?'../../assets/images/little_loading.png':lazy==error?'../../assets/images/little_loading.png'}" alt="" v-lazy="item.thumb[0]">-->
      <img :src="item.thumb[0]" alt="" v-lazy="item.thumb[0]">
     </p>
     <p class='titleBox1'>
      <p class="listTitle">{{item.title}}</p>
      <p class="titleInfo">
       <span class="openApp">打开唐人家</span>
       <span v-if="item.top==true" class="toTop">置顶</span>
       <!--<svg class="icon" aria-hidden="true">
        <use xlink:href="#icon-dianzan" rel="external nofollow" ></use>
       </svg>-->
       <span class="like">阅读 {{item.read}}</span>
       <span class="time">{{item.createAt|formatTime}}</span>
      </p>
    </p>
   </p>
  </p>
</template>
<script>
 import {mapActions, mapState, mapGetters} from 'vuex'
 import moment from 'moment'
 export default{
  data(){
   return {
    lists: [],
    id:this.$route.params.id,
   }
  },
  props:{
    related:Array  //重点是这里
  },
  created(){
   moment.locale('zh-cn');
  },
  /*computed: {
   ...mapState({
    related: state => state.newsDetails.related,
   })
  },*/
  filters:{
   formatTime(time){
    return moment(time).fromNow();
   },
  },
  methods:{
  },
  watch: {
   related (val) {
    this.lists = val;
   },
   '$route'(to,from){
    this.id=this.$route.params.id
   }
  }
 }
</script>

效果如图：

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