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：