BigCommerce Stencil模板中{{#if}}多条件及空值判断问题咨询

Hey there, let's break down why your conditional checks aren't working—Stencil uses Handlebars under the hood, which doesn't support JavaScript-style operators like &&, ==, or != directly in {{#if}} blocks. Here's how to fix your specific use cases:

1. Checking for Both schema and Non-Empty product.brand.name #

Your initial attempts with {{#if schema && product.brand.name '!=' ''}} and {{#all schema product.brand.name '!=' ''}} failed because {{#all}} expects valid Handlebars expressions (not raw comparison operators).

The simplest correct approach is using {{#all}} with truthy checks—Handlebars treats non-empty strings, defined variables, and non-false values as "true":

{{#all schema product.brand.name}}
  <!-- Your code here runs when schema exists AND product.brand.name is not empty/null/undefined -->
{{/all}}

If you need to be stricter (e.g., ignore brand names that are just spaces), combine it with the trim helper:

{{#all schema (trim product.brand.name)}}
  <!-- Runs when schema exists AND brand name has non-whitespace characters -->
{{/all}}

2. Checking if product.brand.name is Empty #

{{#if product.brand.name '==' ''}} doesn't work because Handlebars doesn't parse == in this context. Instead, use {{#unless}} (the equivalent of "if not"):

{{#unless product.brand.name}}
  <!-- Your code here runs when product.brand.name is empty, null, or undefined -->
{{/unless}}

For strict empty string checks (including ignoring whitespace), use trim with {{#unless}}:

{{#unless (trim product.brand.name)}}
  <!-- Runs when brand name is empty or only contains spaces -->
{{/unless}}

Bonus: Custom Value Comparisons #

If you ever need to compare against specific values (e.g., check if the brand name equals "Acme"), use Stencil's built-in {{if_eq}} and {{ifneq}} helpers:

<!-- Check if brand name matches exactly -->
{{#if_eq product.brand.name "Acme"}}
  <p>Brand is Acme!</p>
{{/if_eq}}

<!-- Check if brand name does NOT match -->
{{#ifneq product.brand.name "Acme"}}
  <p>Brand is not Acme!</p>
{{/ifneq}}

内容的提问来源于stack exchange，提问作者Naveed Mazhar