javascript - 基于查找的 Handlebars 条件

Question

我有以下数据结构:

{
    things: [
        "desk",
        "chair",
        "pen",
        "book",
        "lamp"
    ],
    owners: [
        "Julia",
        "Sandra",
        "John",
        "Paul"
    ]
}

什么在起作用:

这个handleblars模板:

{{#each things}}
    <p>This {{this}} belongs to {{lookup ../owners @index}}</p>
{{/each}}

正确输出:

This desk belongs to Julia
This chair belongs to Sandra
This pen belongs to John
This book belongs to Paul
This lamp belongs to

什么不起作用:

现在，我想添加一个条件，因为最后一个 thing 可能没有 owner。模板将类似于:

{{#each things}}
    {{#if lookup ../owners @index}}
        <p>This {{this}} belongs to {{lookup ../owners @index}}</p>
    {{else}}
        <p>...But this {{this}} belongs to nobody</p>
    {{/if}}
{{/each}}

输出:

This desk belongs to Julia
This chair belongs to Sandra
This pen belongs to John
This book belongs to Paul
...But this lamp belongs to nobody

不幸的是，这个{{#if lookup ../owners @index}} 不起作用。

我的问题:是否可以使用内置的 Handlebars 助手来实现这一点，还是我必须编写自定义助手？

Answer 1

你确实可以做你想做的事，使用子表达式:

{{#if (lookup ../owners @index)}}

就像一个魅力。 (来源:Handlebars website)