templates - Meteor:在用数据渲染模板后调用函数

Question

我有很多帖子想在轮播中显示。对于轮播，我使用 OwlCarousel .

    <div class="owl-carousel" id="featured-carousel">
        {{#each featuredPosts}}
        <div>
            <h2>
                {{postTitle}}
            </h2>
        </div>
        {{/each}}
    </div>

我这样称呼轮播:

Template.featuredCarousel.rendered = function(){
$('#featured-carousel').owlCarousel({
    loop:true,
    autoplay:true,
    autoplayTimeout:3000,
    items:1,
    smartSpeed:1080,
    padding:80
});
this.rendered = true;
};

我得到的结果是 Owl 基本上认为我只有一个项目要显示在轮播中，它是多个 div。显然，Template.featuredCarousel.rendered 中的函数在模板的#each-part 完成之前或数据到达之前被调用。

如何使实例化轮播的函数仅在模板完全呈现(包括所有数据)后调用？

非常感谢您的帮助。

P.S.:我使用 iron-router 进行路由，如下所示:

Router.map(function(){
this.route('home', {
    path: '/',
    waitOn: function(){
        return Meteor.subscribe('featured');
    },
    data: function(){
        return {featuredPosts: Featured.find({})};
    }
});
});

P.P.S.:我也尝试过使用加载模板，但这也无济于事。

Answer 1

您已正确地指出您的问题:

What apparently happens is that the function inside Template.featuredCarousel.rendered is called before the #each-part of the template is completed or before the data has arrived.

模板的 rendered 回调仅在您的模板实例首次插入 DOM 时调用一次，因此如果您的数据尚未准备好(从服务器获取)但#each block 将不会不生成任何 HTML 元素，当您实例化轮播时，它将显示为空。

您可以做的是确保您的数据在 rendered 回调触发之前准备就绪。显然你已经尝试设置这个解决方案但没有成功，你确定你像这样添加了默认加载 Hook 吗？

Router.onBeforeAction("loading");

更好的解决方案是在呈现的回调中监听数据库更改，并在首次获取项目时相应地重新初始化轮播，然后动态添加和/或删除项目。

HTML

<template name="carousel">
  <div class="owl-carousel">
    {{#each featuredPosts}}
      {{! item declaration}}
    {{/each}}
  </div>
</template>

JS

function featuredPosts(){
  return Featured.find();
}

Template.carousel.helpers({
  // feed the #each with our cursor
  featuredPosts:featuredPosts
});

Template.carousel.rendered=function(){
  var options={...};
  // first initialization
  this.$(".owl-carousel").owlCarousel(options);
  this.autorun(_.bind(function(){
    // this is how we "listen" for databases change : we setup a reactive computation
    // and inside we reference a cursor (query) from the database and register
    // dependencies on it by calling cursor.forEach, so whenever the documents found
    // by the cursor are modified on the server, the computation is rerun with
    // updated content, note that we use the SAME CURSOR that we fed our #each with
    var posts=featuredPosts();
    // forEach registers dependencies on the cursor content exactly like #each does
    posts.forEach(function(post){...});
    // finally we need to reinit the carousel so it take into account our newly added
    // HTML elements as carousel items, but we can only do that AFTER the #each block
    // has finished inserting in the DOM, this is why we have to use Deps.afterFlush
    // the #each block itself setup another computation and Deps.afterFlush makes sure
    // this computation is done before executing our callback
    Tracker.afterFlush(_.bind(function(){
      this.$(".owl-carousel").data("owlCarousel").reinit(options);
    },this));
  },this));
};

我不熟悉 owl-carousel，所以我不确定 reinit 是否会正常运行(我已经快速检查了文档，但似乎没问题)。

对于没有 reinit 方法的类似 JS 插件(例如 bootstrap carousel)，您可以先检查插件是否已实例化，然后销毁它并重新创建它，如下所示:

var carousel=this.$(".carousel").data("bs.carousel");
if(carousel){
  // bootstrap carousel has no destroy either so we simulate it by pausing it
  // and resetting the data attribute to null (it's a bit messy)
  this.$(".carousel").carousel("pause");
  this.$(".carousel").data("bs.carousel",null);
}
// initialize normally because previous instance was killed
this.$(".carousel").carousel({...});