javascript - 类型错误 : Cannot read property 'push' of undefined Vue JS

Question

我有一个组件正在尝试将数据推送到另一个子组件，Abit 在这里感到困惑，因为我是 Vue.js 的新手。我尝试将子组件导入主组件，但添加项目的推送导致了问题？有什么想法吗？

我收到错误:

类型错误:无法读取未定义的属性“push”

我不明白为什么或在哪里？

主要成分:

<template>
  <div class="container search">
    <list></list>

    <div class="jumbotron">
      <h1 class="display-4">{{title}}</h1>
      <p class="lead">{{intro}}</p>
      <hr class="my-4">
      <p v-if="validated" :class="errorTextClass">Enter a valid search term</p>

      <button
        type="button"
        class="btn btn-primary btn-lg mb-3"
        v-on:click="refreshPage"
        v-if="result.length > 1"
      >
        <font-awesome-icon icon="redo"/>Start again
      </button>
      <input
        class="form-control form-control-lg mb-3"
        type="search"
        placeholder="Search"
        aria-label="Search"
        v-model="search"
        required
        autocomplete="off"
        id="search"
      >

      <div v-for="(result, index) in result" :key="index">
        <div class="media mb-4">
          <img
            :src="resizeArtworkUrl(result)"
            alt="Album Cover"
            class="album-cover align-self-start mr-3"
          >
          <div class="media-body">
            <h4 class="mt-0">
              <button
                type="button"
                class="btn btn-primary btn-lg mb-3 float-right"
                v-on:click="addItem(result)"
              >
                <font-awesome-icon icon="plus"/>
              </button>
              <b>{{result.collectionName}}</b>
            </h4>
            <h6 class="mt-0">{{result.artistName}}</h6>
            <p class="mt-0">{{result.primaryGenreName}}</p>
          </div>
        </div>
      </div>

      <div :class="loadingClass" v-if="loading"></div>

      <button
        class="btn btn-success btn-lg btn-block mb-3"
        type="submit"
        v-on:click="getData"
        v-if="result.length < 1"
      >
        <font-awesome-icon icon="search"/>Search
      </button>
    </div>
  </div>
</template>

<script>
import List from "../components/myList.vue";

export default {
  name: "Hero",
  props: {
    List
  },
  components: {
    List
  },
  data: function() {
    return {
      title: "Simple Search",
      intro: "This is a simple hero unit, a simple jumbotron-style.",
      subintro:
        "It uses utility classes for typography and spacing to space content out.",
      result: [],
      errors: [],
      search: "",
      loading: "",
      message: false,
      isValidationAllowed: false,
      loadingClass: "loading",
      errorTextClass: "error-text"
    };
  },

  watch: {
    search: function(val) {
      if (!val) {
        this.result = [];
      }
    }
  },

  computed: {
    validated() {
      return this.isValidationAllowed && !this.search;
    }
  },

  methods: {
    getData: function() {
      this.isValidationAllowed = true;
      this.loading = true;
      fetch(`xxxxxxxx`)
        .then(response => response.json())
        .then(data => {
          this.result = data.results;
          this.loading = false;
          /* eslint-disable no-console */
          console.log(data);
          /* eslint-disable no-console */
        });
    },
    refreshPage: function() {
      this.search = "";
    },
    addItem: function(result) {
      this.myList.push(result);
    },

    resizeArtworkUrl(result) {
      return result.artworkUrl100.replace("100x100", "160x160");
    }
  }
};
</script>

<style>
.loading {
  background-image: url("../assets/Rolling-1s-42px.gif");
  background-repeat: no-repeat;
  height: 50px;
  width: 50px;
  margin: 15px;
  margin-left: auto;
  margin-right: auto;
}

.error-text {
  color: red;
}

.media {
  text-align: left;
}

.album-cover {
  width: 80px;
  height: auto;
}
</style>

子组件:

<template>
  <div class="mb-5 container">
    <button type="button" class="btn btn-primary mt-2 mb-2 btn-block">
      My List
      <span class="badge badge-light">{{myList.length}}</span>
    </button>
    <ul class="list-group" v-for="(result, index) in myList" :key="index">
      <li class="list-group-item">
        <b>{{result.collectionName}}</b>
        <h6 class="mt-0">{{result.artistName}}</h6>
        <p class="mt-0">{{result.primaryGenreName}}</p>
      </li>
    </ul>
  </div>
</template>

<script>

export default {
  name: "List",

  data: function() {
    return {
      myList: [],
      result: []
    };
  }
}
</script>

Answer 1

数据应该始终从父组件流向子组件；子组件不应修改属于父组件的数据。

如果您希望主组件能够将项目推送到 myList，那么 myList 应属于主组件，并通过以下方式将其传递给子组件:一个 Prop 。

简化示例:

主要成分

<list :list="list"/>
<button @click="addItem">Add Item</button>

import List from './list.vue'

export default {
  components: {
    List
  },
  data() {
    return {
      list: []
    }
  },
  methods: {
    addItem() {
      this.list.push('New Item')
    }
  }
}

列表组件

<ul>
  <li v-for="item of list">{{ item }}</li>
</ul>

export default {
  props: ['list']
}