Question

我正在学习Vue，无法理解一件事。我一直收到这个错误：

属性或方法“item”未在实例上定义，但在呈现期间引用。通过初始化属性，确保此属性在数据选项或基于类的组件中是被动的。请参阅：https://vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties。

显然我读过这篇文章并考虑过我的代码，但由于我正在使用Vue的push（）方法（应该做的事情），我仍然无法理解为什么它不起作用。有人可以对此有所了解吗？

我在下面分享一些代码：

var maxpages = parseInt(rest_object.maxpages);

Vue.component('news-item', {
  template: '#news-template'
  ,props:['newsdata']
})

var news_manager = new Vue({
  el: '#more-news-box'
  ,data:{
    page: 1 
    ,add_more_button: null
    ,items: []
  }
  ,mounted: function(){
    this.add_more_button = $('button.add-more');

  }
  ,methods: {
    get_posts: function(){
      this.page += 1;
      if(this.page > maxpages) return false;
      if(this.page == maxpages) this.add_more_button.prop('disabled','disabled').addClass('hidden');

      $.ajax({
        type: 'GET'
        ,dataType: 'json'
        ,url: rest_object.api_url
        ,data: { per_page: 3 ,page: this.page }
      }).done(function(posts_objects) {
        _.each(posts_objects, function(post){ this.items.push(post); }.bind(this));
      }.bind(this));
    }
  }
});

HTML：

<div class="more-news-box" id="more-news-box">
  <ul><li v-for="(item, index) in items" is="news-item" :key="index" :newsdata="item"></li></ul>
  <button class="add-more" type="button" @click="get_posts">add more</button>
</div>


<script type="text/x-template" id="news-template">
  <li>
    <article class="news-article">
      <figure class="news-figure"></figure>
      <div class="news-date news-component"></div>
      <h3 class="news-title news-component">{{ item.title.rendered }}</h3>
      <div class="news-content news-component"></div>
    </article>
  </li>
</script>

Answer 1

组件模板引用item，但item未在组件中的任何位置声明为属性。

<h3 class="news-title news-component">{{ item.title.rendered }}</h3>

相反，组件声明了newsdata属性。我希望你想要的是这个：

<h3 class="news-title news-component">{{ newsdata.title.rendered }}</h3>

这里是代码（略有修改，因此API调用有效）。

＆＃13;

console.clear()

var maxpages = 10

Vue.component('news-item', {
  template: '#news-template'
  ,props:['newsdata']
})

var news_manager = new Vue({
  el: '#more-news-box'
  ,data:{
    page: 1 
    ,add_more_button: null
    ,items: []
  }
  ,mounted: function(){
    this.add_more_button = $('button.add-more');

  }
  ,methods: {
    get_posts: function(){
      this.page += 1;
      if(this.page > maxpages) return false;
      if(this.page == maxpages) this.add_more_button.prop('disabled','disabled').addClass('hidden');

      $.ajax({
        type: 'GET'
        ,dataType: 'json'
        ,url: "https://swapi.co/api/people"
        ,data: { per_page: 3 ,page: this.page }
      }).done(function(posts_objects) {
        console.log(posts_objects)
        _.each(posts_objects.results, function(post){ this.items.push({title:{rendered:post.name}}); }.bind(this));
        console.log(this.items)
      }.bind(this));
    }
  }
});

＆＃13;

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://unpkg.com/vue@2.4.2"></script>

<div class="more-news-box" id="more-news-box">
  <ul><li v-for="(item, index) in items" is="news-item" :key="index" :newsdata="item"></li></ul>
  <button class="add-more" type="button" @click="get_posts">add more</button>
</div>


<script type="text/x-template" id="news-template">
  <li>
    <article class="news-article">
      <figure class="news-figure"></figure>
      <div class="news-date news-component"></div>
      <h3 class="news-title news-component">{{ newsdata.title.rendered }}</h3>
      <div class="news-content news-component"></div>
    </article>
  </li>
</script>

＆＃13;

如何在Vue js 2组件中避免对象引用问题？

1 个答案: