Processing parent component method updates to child components that cannot be rendered

This time I will bring you some precautions when dealing with parent component method updates until the child component cannot be rendered, and what are the precautions when dealing with parent component method updates until the child component cannot be rendered. The following is a practical case, let's take a look.

Scenario:

What I actually use is this. My parent component refers to the child component related, and the parent component calls to get the page details. method, the state value related is updated, and the sub-component renders related news content based on the related. However, when the page is opened, the sub-component is always loaded first. The sub-component has not obtained the updated related value when rendering, even if the sub-component is rendered. Changes in the watch value in the component still cannot render the relevant news content of the sub-component.

My solution:

The parent component passes the value to the child component. When the parent component executes the method of getting page details, state The related value is updated and then passed to the subcomponent, which is then rendered and can be obtained normally.

Parent component code:

<template>
 <p>
  <mt-header>
   <router-link>
    <mt-button></mt-button>
   </router-link>
  </mt-header>
  </p>
<p>
   </p>
<h1>
    {{ title }}
   </h1>
   <p>
    </p>
<ul>
     <li>
      <span>{{pubName}}</span>
     </li>
     <li>
      <span>{{authorName}}</span>
      <span>{{createAt|formatTime}}</span>
     </li>
    </ul>
    <span>关注</span>
   
   <p>
    </p>
<p></p>
    <p>责任编辑：{{editorName}}</p>
   
   <p>阅读全文</p>
   <related></related>
　　　　<!--重点是这里 父组件向子组件传值-->
   </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);
   },
  }
 }

Sub component related.vue

<template>
  <p>0">
    </p>
<p><span>相关新闻</span></p>
    <p>
     </p>
<p>
      <!--<img src="/static/imghwm/default1.png"  data-src="{lazy==loaded?item.thumb[0]:lazy==loading?&#39;../../assets/images/little_loading.png&#39;:lazy==error?&#39;../../assets/images/little_loading.png&#39;}"  class="lazy"  : alt="" v-lazy="item.thumb[0]">-->
      <img  src="/static/imghwm/default1.png" data-src="item.thumb[0]" class="lazy" alt="Processing parent component method updates to child components that cannot be rendered" >
     </p>
     <p>
      </p>
<p>{{item.title}}</p>
      <p>
       <span>打开唐人家</span>
       <span>置顶</span>
       <!--<svg class="icon" aria-hidden="true">
        <use xlink:href="#icon-dianzan" rel="external nofollow" ></use>
       </svg>-->
       <span>阅读 {{item.read}}</span>
       <span>{{item.createAt|formatTime}}</span>
      </p>
    
   
  
</template>
<script>
 import {mapActions, mapState, mapGetters} from &#39;vuex&#39;
 import moment from &#39;moment&#39;
 export default{
  data(){
   return {
    lists: [],
    id:this.$route.params.id,
   }
  },
  props:{
    related:Array  //重点是这里
  },
  created(){
   moment.locale(&#39;zh-cn&#39;);
  },
  /*computed: {
   ...mapState({
    related: state => state.newsDetails.related,
   })
  },*/
  filters:{
   formatTime(time){
    return moment(time).fromNow();
   },
  },
  methods:{
  },
  watch: {
   related (val) {
    this.lists = val;
   },
   &#39;$route&#39;(to,from){
    this.id=this.$route.params.id
   }
  }
 }
</script>

The effect is as shown:

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

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