javascript - 如何避免在使用 v-for 的元素上使用 v-if

Question

我有一个像这样的文字对象:

    export default {
        pizze:{
            type:"pizze",
            typeOne:{
                title: "Pizze Rosse",
                data:[
                    {id:1,type:"pizza",name:"Margherita",price:4,ingredients:["pomodoro","mozzarella"],quantity:0,inventory:100},
                    {id:2,type:"pizza",name:"Marinara",price:3.5,ingredients:["aglio","pomodoro"],quantity:0,inventory:100},
                    {id:3,type:"pizza",name:"Salsiccia e funghi",price:6,ingredients:["salsiccia","funghi","mozzarella","pomodoro"],quantity:0,inventory:100},
                    {id:4,type:"pizza",name:"Carciofi",price:4,ingredients:["mozzarella","carciofi","pomodoro"],quantity:0,inventory:100},  
                ]
            },
            typeTwo:{
                title:"Pizze Bianche",
                data:[
                    {id:5,type:"pizza",name:"Gorgonzola e noci",price:5.50,ingredients:["gorgonzola","noci","mozzarella"],quantity:0,inventory:100},
                    {id:6,type:"pizza",name:"Stracchino e rucola",price:4.50,ingredients:["stracchino","rucola","basilico"],quantity:0,inventory:100},
                    {id:7,type:"pizza",name:"Tartufo e salsiccia",price:8,ingredients:["tartufo","salsiccia","mozzarella"],quantity:0,inventory:100},
                    {id:8,type:"pizza",name:"Zucchine e Gamberi",price:5,ingredients:["zucchine","gamberi","pomodorini"],quantity:0,inventory:100},
                ]
    
            }
        },
        primiPiatti:{
            type:"primiPiatti",
            typeOne:{
                title: "Primi di carne",
                data:[
                    {id:12,type:"primiPiatti",name:"Lasagne alla Bolognese",price:9,quantity:0,inventory:100},
                    {id:13,type:"primiPiatti",name:"Spaghetti alla carbonara",price:14,quantity:0,inventory:100},
                    {id:14,type:"primiPiatti",name:"pennette all'amatriciana",price:10,quantity:0,inventory:100},
                    {id:15,type:"primiPiatti",name:"paccheri salsiccia e funghi",price:12,quantity:0,inventory:100},  
                ]
            },
            typeTwo:{
                title:"Primi di pesce",
                data:[
                    {id:16,type:"primiPiatti",name:"spaghetti allo scoglio",price:8.50,quantity:0,inventory:100},
                    {id:17,type:"primiPiatti",name:"zuppa di cozze",price:14.50,quantity:0,inventory:100},
                    {id:18,type:"primiPiatti",name:"pappardelle asparagi e gamberi",price:18,quantity:0,inventory:100},
                    {id:19,type:"primiPiatti",name:"lasagne al salmone",price:15,quantity:0,inventory:100},
                ]
    
            },
...

我不知道使用 v-if inside a v-for loop 不好我在 View 中显示代码的第一种方法是:

<div class="menu__container">
          <div v-if="menuVoice!=='type'"class="menu__container--box" v-for="menuVoice in Object.keys(menuData)" :key="menuVoice">
              <div class="title">{{menuData[menuVoice].title}}</div>
              <item-record v-for="data in menuData[menuVoice].data" :key="data.id" :data="data"></item-record>
          </div>
        </div> 

我试图做的是避免显示与对象 MenuVoice 的 type 属性相关的 div block 。因为我需要它用于其他目的(例如检索正确的对象)。所以我以这种方式重构了代码:

<div class="menu__container">
          <div :style="[menuVoice === 'type' ? {display:'none'} : {display:'block'}]" class="menu__container--box" v-for="menuVoice in Object.keys(menuData)" :key="menuVoice">
              <div class="title">{{menuData[menuVoice].title}}</div>
              <item-record v-for="data in menuData[menuVoice].data" :key="data.id" :data="data"></item-record>
          </div>
        </div> 

我不确定是否可以，因为那里总有一个 if 语句。代码在这两种情况下都有效，但我想知道是否有更好的方法来做类似的事情。

我还尝试将 v-if 向下移动到子 div 上，如下所示:

<div class="menu__container">
          <div"class="menu__container--box" v-for="menuVoice in Object.keys(menuData)" :key="menuVoice">
            <div v-if="menuVoice !=='type'>
                <div class="title">{{menuData[menuVoice].title}}</div>
              <item-record v-for="data in menuData[menuVoice].data" :key="data.id" :data="data"></item-record>
            </div>  
          </div>
        </div> 

但它不起作用，因为我仍然会得到三个类为 '.menu__container--box' 的 div。

Answer 1

避免将 v-if 与 v-for 一起使用的技巧是使用计算属性过滤数据集。

我在这里创建了一个名为 menuList 的计算，它过滤 menuData，返回过滤后的浅层克隆。

computed: {
  menuList() {
    return Object.keys(this.menuData)
      .filter(key => key !== 'type')
      .reduce((res, key) => (res[key] = this.menuData[key], res), {});
  }
}

因此您的模板使用开箱即用的正确列表。 v-for="(item, key) in menuList"

<div class="menu__container">
  <div class="menu__container--box" v-for="(item, key) in menuList" :key="key">
      <div class="title">{{item.title}}</div>
      <item-record v-for="data in item.data" 
                   :key="data.id" :data="data"></item-record>
  </div>
</div>

模板逻辑应保持在最低限度。任何超出对值的引用或简单赋值的内容都应移至计算和方法中。