在Meteor中制作模板助手 [英] Making a template helper reactive in Meteor

问题描述

我正在构建一个聊天应用程序，在我的新聊天页面上，我有一个联系人列表，您可以通过点击它们逐个选择（我在其上应用CSS选择的类并将用户ID推送到数组名为'newChatters'。

I am building a chat application and on my "new chats" page I have a list of contacts, which you can select one by one by tapping them (upon which I apply a CSS selected class and push the user id into an array called 'newChatters'.

我想让这个数组可用于帮助方法，这样我就可以显示一个名单的反应列表，所有用户都被添加到聊天。

I want to make this array available to a helper method so I can display a reactive list of names, with all users who have been added to the chat.

我想要显示被动列表的模板：

The template that I want to display the reactive list in:

<template name="newChatDetails">
  <div class="contactHeader">
    <h2 class="newChatHeader">{{newChatters}}</h2>
  </div>
</template>

只要选择了联系人，就会触发clickItem事件：

The click contactItem event triggered whenever a contact is selected:

Template.contactsLayout.events({
 'click #contactItem': function (e) {
   e.preventDefault();
   $(e.target).toggleClass('selected');
   newChatters.push(this.username);
...

newChatters数组正在正确更新所以到目前为止一切都是工作正常。现在我需要让{{newChatters}}被动地更新。这是我尝试过的但它不正确且不起作用：

The newChatters array is getting updated correctly so up to this point all is working fine. Now I need to make {{newChatters}} update reactively. Here's what I've tried but it's not right and isn't working:

Template.newChatDetails.helpers({
  newChatters: function() {
    return newChatters;
  }
});

我如何以及在何处使用Deps.autorun（）来完成这项工作？我是否甚至需要它，因为我认为辅助方法无论如何都会自动更新失效？

How and where do I use Deps.autorun() to make this work? Do I even need it, as I thought that helper methods auto update on invalidation anyway?

推荐答案

1）定义 Tracker.Dependency 在您定义对象的同一个地方：

1) Define Tracker.Dependency in the same place where you define your object:

var newChatters = [];
var newChattersDep = new Tracker.Dependency();

2）在你之前使用 depend（）从对象中读取：

2) Use depend() before you read from the object:

Template.newChatDetails.newChatters = function() {
  newChattersDep.depend();
  return newChatters;
};

3）在你之后使用 changed（）写：

3) Use changed() after you write:

Template.contactsLayout.events({
  'click #contactItem': function(e, t) {
    ...
    newChatters.push(...);
    newChattersDep.changed();
  },
});

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