condition.md

Condition

Condition tags are useful for making decisions about what code to run, based on some specific value under inspection.

Often, condition tags are concerned with whether a value is truthy or falsey. In Liquid, only the values false and nil are falsey; all other values are truthy.

{% hint style="info" %} For further discussion on how Liquid treats values, see their documentation: Truthiness and falsiness in Liquid. {% endhint %}

if

An if tag is always paired with an endif tag. The code between these tags only runs if the condition in the if tag evaluates to something truthy.

{% raw %}
{% if options.test_mode__boolean %}
  {% action "echo" summaries %}
{% endif %}
{% endraw %}

unless

Identical in style to the if tag, the unless tag only executes the code it contains if the condition is falsey.

{% raw %}
{% unless options.default_tracking_url_template contains "TRACKING_NUMBER" %}
  {% error %}{{ "Placeholder 'TRACKING_NUMBER' is missing." | json }}{% enderror %}
{% endunless %}
{% endraw %}

else

An else tag can be added within if, unless, and case blocks. The code that follows the else tag is run if the condition above it does not run.

{% raw %}
{% if customer.email != empty %}
  {% assign email = customer.email %}
{% else %}
  {% log "Customer had no email" %}
{% endif %}
{% endraw %}

{% raw %}
{% unless customer.email == empty %}
  {% assign email = customer.email %}
{% else %}
  {% log "Customer had no email" %}
{% endif %}
{% endraw %}

elsif

An elsif tag adds a second condition to an if or unless block. If the condition above it does not run, the next elsif tag will be evaluated – and if its condition is truthy, the code that follows it will run.

Any number of elsif tags may be added within if or unless blocks.

{% raw %}
{% assign today = "tuesday" %}

{% if today == "monday" %}
  {% log "it's monday!" %}
{% elsif today == "tuesday" %}
  {% log "it's tuesday!" %}
{% endif %}
{% endraw %}

{% raw %}
{% assign today = "tuesday" %}

{% unless today == "tuesday" %}
  {% log "it's not tuesday!" %}
{% elsif today == "tuesday" %}
  {% log "it's tuesday!" %}
{% endif %}
{% endraw %}

case, when

The case and endcase tag pair contain a series of when tags, and optionally an else tag. The value specified in the case tag is inspected, and Liquid then looks for a when tag that has a matching value. If one is found, that when tag gets to run its code. If no match is found, the code for the else tag (if given) is run.

{% raw %}
{% case order.cancel_reason    %}
  {% when "customer" %}
    {% assign cancel_reason = "It was the customer." %}
  {% when "fraud" %}
    {% assign cancel_reason = "It was fraud!" %}
  {% when "inventory" %}
    {% assign cancel_reason = "It was due to inventory issues." %}
  {% else %}
    {% assign cancel_reason = "It was something unknown." %}
{% endcase %}
{% endraw %}