vue(ref父组件使用子组件中定义的方法)

一、前言                                                                   

二、主要内容                                                            

1、实现效果（其实可以直接在父组件中操作子组件的显示隐藏，但是这里通过在子组件定义自己的显示隐藏效果，让父组件调用，训练一下这种方式）

2、分析：

　　（1）点击父组件的某一个li项，跳出这个商品详情（子组件项）

       （2）子组件中还是需要接收到父组件中的food,但是这个food不像上一篇那样是固定的，所以这里的这个food是根据我们点击的不同的项，传进去的

       （3）为了实现上一步分析：我们需要在data中定义一个对象，点击的时候，将当前对象的food传进去，然后在传给子组件，这样就能实现动态传递food了

3、具体实现

　　（1）父组件中先引入并且使用子组件

　　（2）在父组件的每一项上添加一个点击事件，并且将当前项的food通过定义的这个函数传给子组件

<!--点击的时候将当前的food传进去-->
<li class="food-item bottom-border-1px" v-for="(food, index) in good.foods" :key="index" @click="showFood(food)">
                //省略
                  </div>
                </div>
</li>

　　（3）metods:中定义这个方法接收并传过去

 <template>
 <Food :food="food" ref="food"></Food>
</template>

<script>

      data(){
          return{
              scrollY:0,
              tops:[], //存放每一个类的初始位置
        food:{}

          }
      }

      components:{
          
          Food
      }
    // 显示点击的food
      showFood (food) {
        // 设置food
        this.food = food
       
      }
</script>

　　（4）在子组件中要定义该组件的显示隐藏方法，先用一个标识来标记

export default {
    props: {
      food: Object
    },

    data () {
      return {
        isShow: false
      }
    },

    methods: {
      toggleShow () {
        this.isShow = !this.isShow
      }
    },

    components: {
      CartControl
    }
  }

　　（5）父组件中用this.$refs.refname.method()来得到子组件的方法，并且执行

 // 显示点击的food
      showFood (food) {
        // 设置food
        this.food = food
        // 显示food组件 (在父组件中调用子组件对象的方法)
        this.$refs.food.toggleShow()
      }

4、完整代码：

父组件：

<template>
  <div>
    <div class="goods">
      <div class="menu-wrapper"  >
        <ul>
          <!--current-->
          <li class="menu-item " v-for="(good,index) in goods" :key="index" :class="{current:index===currentIndex}" @click="clickMenuItem(index)">
            <span class="text bottom-border-1px">
              <img class="icon" :src="good.icon" v-if="good.icon" >
              {{good.name}}
            </span>
          </li>
        </ul>
      </div>
      <div class="foods-wrapper">
        <ul ref="foodsUl">
          <li class="food-list-hook" v-for="(good, index) in goods" :key="index" >
            <h1 class="title">{{good.name}}</h1>
            <ul>
              <li class="food-item bottom-border-1px" v-for="(food, index) in good.foods" :key="index" @click="showFood(food)">
                <div class="icon">
                  <img width="57" height="57" :src="food.icon">
                </div>
                <div class="content">
                  <h2 class="name">{{food.name}}</h2>
                  <p class="desc">{{food.description}}</p>
                  <div class="extra">
                    <span class="count">月售{{food.sellCount}}份</span>
                    <span>好评率{{food.rating}}%</span>
                  </div>
                  <div class="price">
                    <span class="now">￥{{food.price}}</span>
                    <span class="old" v-if="food.oldPrice">￥{{food.oldPrice}}</span>
                  </div>
                  <div class="cartcontrol-wrapper">
                   <CartControl :food='food'></CartControl>
                  </div>
                </div>
              </li>
            </ul>
          </li>
        </ul>
      </div>
      <Food :food="food" ref="food"></Food>
    </div>
       
  </div>
</template>

<script>
    import {mapState} from 'vuex'
    import BScroll from 'better-scroll'
    import CartControl from '../../../components/CartControl/CartControl'
  import Food from '../../../components/Food/Food'
  export default {
      data(){
          return{
              scrollY:0,
              tops:[], //存放每一个类的初始位置
        food:{}

          }
      },
      components:{
          CartControl,
      Food
      },
      //这里的数据是异步显示的,所以我们要等数据异步请求之后再创建这个滑动列表
      mounted(){
          //异步请求可以传过去两个参数，
       this.$store.dispatch('getShopGoods',()=>{
           //数据请求完之后再执行这里了
          //初始化滚动
          this.$nextTick(()=>{
              //初始化，并且实时获取滚动坐标
             this._initScrollY()

            //初始化右边的数组
             this._initTops();
          })       
       })
      },
      methods:{
          //初始化BScroll
          _initScrollY(){
              new BScroll('.menu-wrapper',{
                  click:true

               })
               //创建右边的
               this.foodswrapper = new BScroll('.foods-wrapper',{
                   click:true,
                   probeType:3

               })

               //给右侧绑定的BScroll绑定监听事件,但是你会发现并没有调用
               this.foodswrapper.on('scroll',({x,y})=>{
                   console.log(x,y)//默认没有分发滚动事件
                   this.scrollY=Math.abs(y);
               })

               //获取停下来的位置
               //给右侧绑定的BScroll绑定监听事件,但是你会发现并没有调用
               this.foodswrapper.on('scrollEnd',({x,y})=>{
                   //console.log(x,y)//默认没有分发滚动事件
                   this.scrollY=Math.abs(y);
               })
          }


        //初始化数组，获取到每个li 的坐标
        ,_initTops(){
            var tops=[] //定义一个空数组
            let top=0;
            tops[0]=0 //第一个li的坐标为0

            var lis = this.$refs.foodsUl.children; //获取到了每个li
            Array.prototype.slice.call(lis).forEach((li,index)=>{
                top = top + li.clientHeight//当前的位置，等于上一个的位置，加上这一个的高度
                tops.push(top)
            })

            this.tops=tops
            console.log(tops)

        },
//将当前的index传进来
        clickMenuItem(index){
           //先得到目标位置scrollY
           const top = this.tops[index];
           // 立即更新scrollY,更新当前分类，点击的分类项成为当前
           this.scrollY=top
           //平滑滚动右侧列表
           this.foodswrapper.scrollTo(0, -top, 3);




        },
        // 显示点击的food
      showFood (food) {
        // 设置food
        this.food = food
        // 显示food组件 (在父组件中调用子组件对象的方法)
        this.$refs.food.toggleShow()
      }
    

      },
      computed:{
          ...mapState(['goods']),
          currentIndex(){
              return this.tops.findIndex((top,index)=>{
                return this.scrollY>=top && this.scrollY<this.tops[index+1]
              })
          }
      }
  }
   
</script>

<style lang="stylus" rel="stylesheet/stylus">
  @import "../../../common/stylus/mixins.styl"
  .goods
    display: flex
    position: absolute
    top: 195px
    bottom: 46px
     100%
    background: #fff;
    overflow: hidden
    .menu-wrapper
      flex: 0 0 80px
       80px
      background: #f3f5f7
      .menu-item
        display: table
        height: 54px
         56px
        padding: 0 12px
        line-height: 14px
        &.current
          position: relative
          z-index: 10
          margin-top: -1px
          background: #fff
          color: $green
          font-weight: 700
          .text
            border-none()
        .icon
          display: inline-block
          vertical-align: top
           12px
          height: 12px
          margin-right: 2px
          background-size: 12px 12px
          background-repeat: no-repeat
        .text
          display: table-cell
           56px
          vertical-align: middle
          bottom-border-1px(rgba(7, 17, 27, 0.1))
          font-size: 12px
    .foods-wrapper
      flex: 1
      .title
        padding-left: 14px
        height: 26px
        line-height: 26px
        border-left: 2px solid #d9dde1
        font-size: 12px
        color: rgb(147, 153, 159)
        background: #f3f5f7
      .food-item
        display: flex
        margin: 18px
        padding-bottom: 18px
        bottom-border-1px(rgba(7, 17, 27, 0.1))
        &:last-child
          border-none()
          margin-bottom: 0
        .icon
          flex: 0 0 57px
          margin-right: 10px
        .content
          flex: 1
          .name
            margin: 2px 0 8px 0
            height: 14px
            line-height: 14px
            font-size: 14px
            color: rgb(7, 17, 27)
          .desc, .extra
            line-height: 10px
            font-size: 10px
            color: rgb(147, 153, 159)
          .desc
            line-height: 12px
            margin-bottom: 8px
          .extra
            .count
              margin-right: 12px
          .price
            font-weight: 700
            line-height: 24px
            .now
              margin-right: 8px
              font-size: 14px
              color: rgb(240, 20, 20)
            .old
              text-decoration: line-through
              font-size: 10px
              color: rgb(147, 153, 159)
          .cartcontrol-wrapper
            position: absolute
            right: 0
            bottom: 12px
</style>

子组件：

<template>
  <div class="food" v-if="isShow">
    <div class="food-content">
      <div class="image-header">
        <img :src="food.image">
        <p class="foodpanel-desc">{{food.info}}</p>
        <div class="back" @click="toggleShow">
          <i class="iconfont icon-arrow_left"></i>
        </div>
      </div>
      <div class="content">
        <h1 class="title">{{food.name}}</h1>
        <div class="detail">
          <span class="sell-count">月售{{food.sellCount}}份</span>
          <span class="rating">好评率{{food.rating}}%</span>
        </div>
        <div class="price">
          <span class="now">￥{{food.price}}</span>
          <span class="old" v-show="food.oldPrice">￥{{food.oldPrice}}</span>
        </div>
        <div class="cartcontrol-wrapper">
          <CartControl :food="food"/>
        </div>
      </div>
    </div>
    <div class="food-cover" @click="toggleShow"></div>
  </div>
</template>


<script>
  import CartControl from '../CartControl/CartControl.vue'

  export default {
    props: {
      food: Object
    },

    data () {
      return {
        isShow: false
      }
    },

    methods: {
      toggleShow () {
        this.isShow = !this.isShow
      }
    },

    components: {
      CartControl
    }
  }
</script>

<style lang="stylus" rel="stylesheet/stylus" scoped>
  @import "../../common/stylus/mixins.styl"

  .food
    position: fixed
    left: 0
    top: 0
    bottom: 48px
    z-index: 101
     100%
    &.fade-enter-active, &.fade-leave-active
      transition opacity .5s
    &.fade-enter, &.fade-leave-to
      opacity 0
    .food-content
      position absolute
      left 50%
      top 50%
      transform translate(-50%, -50%)
      width 80%
      height 65%
      z-index 66
      background #fff
      border-radius 5px
      .image-header
        position: relative
         100%
        height: 0
        padding-top: 100%
        img
          position: absolute
          top: 0
          left: 0
           100%
          height: 100%
        .foodpanel-desc
          font-size 10px
          color #ddd
          letter-spacing 0
          position absolute
          bottom 0
          left 0
          right 0
          padding 0 10px 10px
        .back
          position: absolute
          top: 10px
          left: 0
          .icon-arrow_left
            display: block
            padding: 10px
            font-size: 20px
            color: #fff
      .content
        position: relative
        padding: 18px
        .title
          line-height: 14px
          margin-bottom: 8px
          font-size: 14px
          font-weight: 700
          color: rgb(7, 17, 27)
        .detail
          margin-bottom: 18px
          line-height: 10px
          height: 10px
          font-size: 0
          .sell-count, .rating
            font-size: 10px
            color: rgb(147, 153, 159)
          .sell-count
            margin-right: 12px
        .price
          font-weight: 700
          line-height: 24px
          .now
            margin-right: 8px
            font-size: 14px
            color: rgb(240, 20, 20)
          .old
            text-decoration: line-through
            font-size: 10px
            color: rgb(147, 153, 159)
        .cartcontrol-wrapper
          position: absolute
          right: 12px
          bottom: 12px
        .buy
          position: absolute
          right: 18px
          bottom: 18px
          z-index: 10
          height: 24px
          line-height: 24px
          padding: 0 12px
          box-sizing: border-box
          border-radius: 12px
          font-size: 10px
          color: #fff
          background: rgb(0, 160, 220)
          &.fade-transition
            transition: all 0.2s
            opacity: 1
          &.fade-enter, &.fade-leave
            opacity: 0
    .food-cover
      position absolute
      top 0
      right 0
      bottom -48px
      left 0
      z-index 55
      background-color rgba(0, 0, 0, 0.5)

</style>

三、总结