如何根据集合的大小制作模板条件？ [英] How do I make a template conditional based on a collection's size?

问题描述

我想做这样的事情：

 < template name =list> 
< ul> 
 {{#if items}} 
 {{#each items}} 
< li> {{itemContents}}< / li> 
 {{/ each}} 
 {{else}} 
< li class =placeholder>此列表中没有项目。< / li> 
 {{/ if}} 
< ul> 
< / template> 
  

其中项目是一个Meteor.cursor：

  Template.list.items = function（）{
 return Items.find（）; 
}; 
  

然而，上面的代码不起作用，因为即使没有项目（这是轻度惊讶，因为Handlebars评估 [] 为falsey）。我尝试将条件改为

  {{＃if items.count}} 
  

但是我得到了一个神秘的错误

 未知帮助'物品'
  

那么，有没有办法在流星Handlebars模板中编写这样的条件？

解决方案

这是正确的方法：

 < template name =list> 
< ul> 
 {{#each items}} 
< li> {{itemContents}}< / li> 
 {{else}} 
< li class =placeholder>此列表中没有项目。< / li> 
 {{/ each}} 
< ul> 
< / template> 
  

有关详细信息，请参阅 handlebarsjs.com 。

（流星使用 Spacebars ，它的灵感来自Handlebars，所以Syntax几乎相同。）

I want to do something like this:

<template name="list">
  <ul>
  {{#if items}}
      {{#each items}}
        <li>{{itemContents}}</li>
      {{/each}}
  {{else}}
    <li class="placeholder">There are no items in this list.</li>
  {{/if}}
  <ul>
</template>

where items is a Meteor.cursor:

Template.list.items = function() {
  return Items.find();
};

However, the code above doesn't work, as the conditional will evaluate positively even if there are no items (which is mildly surprising because Handlebars evaluates [] as falsey). I tried changing the condition to

{{#if items.count}}

but then I get the cryptic error

Unknown helper 'items'

So, is there a way to write such a condition within a meteor Handlebars template?

解决方案

This would be the correct way to go:

<template name="list">
  <ul>
  {{#each items}}
    <li>{{itemContents}}</li>
  {{else}}
    <li class="placeholder">There are no items in this list.</li>
  {{/each}}
  <ul>
</template>

For further information take a look at handlebarsjs.com.

(Meteor uses Spacebars which is inspired by Handlebars. So the Syntax is almost the same.)

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