handlerbars.js check if list is empty

问题:

Is there a way in Handlebars.js templating to check if the collection or list is null or empty, before going and iterating through the list/collection?

// if list is empty do some rendering ... otherwise do the normal
{{#list items}}

{{/list}}



{{#each items}}

{{/each}}

回答1:

The "each" tag can take an "else" section too. So the simplest form is:

{{#each items}}
// render item
{{else}}
// render empty
{{/each}}

回答2:

If you have something that you want to display once and only if the array has data, use

{{#if items.length}}
    //Render
{{/if}}

.length will return 0 for empty arrays so we have achieved a real falsey value.

回答3:

Ok it's simpler than I thought:

{{#if items}}
// render items

{{#each items}}
// render item
{{/each}}

{{else}}
// render empty
{{/if}}

回答4:

If you want to check if a collection (cursor) is empty or not, the previous answers won't be useful, instead you must use the count() method :

{{#if items.count}}
    <p>There is {{items.count}} item(s).</p>
{{else}}
    <p>There is nothing</p>
{{/if}}

回答5:

For anyone who needs to use an {{#each}} on top of {{#if}} (i.e. an if loop inside a for loop). Is they have three different list of arrays.

Using a lookup inside a if statement solves the issue for me. As, the above answers did not solve my issue.

Here is my code,

{{#each OtherRandomItems}}

  {{this}}

  {{lookup ../AnotherRandomItems @index}}

  {{#if (lookup ../RandomItems @index)}}
  // render items
  {{else}}
  // render empty
  {{/if}}

{{/each}}