Monitor for variants with zero price, with Mechanic.

user/product_update/variants_zero_price

{% assign mechanic_user_topic = options.mechanic_user_topic__required %}
{% assign alert_email_recipients = options.alert_email_recipients__array_required %}
{% assign cache_alert_seconds = options.cache_alert_for_x_hours__number | round: 0 | at_least: 0 | times: 3600 %}

{% if event.topic == mechanic_user_topic %}
  {% if event.preview %}
    {% capture product_json %}
      {
        "id": 1234567890,
        "title": "Analog Short",
        "status": "active",
        "published_at": "2026-05-02T17:21:53-07:00",
        "variants": [
          {
            "id": 1234567890,
            "title": "White",
            "sku": "ALOG-SHR-WT",
            "price": "0.00"
          }
        ]
      }
    {% endcapture %}
  
    {% assign product = product_json | parse_json %}
  {% endif %}

  {% comment %}
    -- this custom webhook should only fire if the product is active, published to the online store, and has at least one variant with a no price
    -- BUT, let's check all that just in case :)
  {% endcomment %}

  {% assign zero_price_variants
    = product.variants
    | where: "price", "0.00"
    | sort: "id"
  %}

  {% if product.status != "active" or product.published_at == blank or zero_price_variants == blank %}
    {% log "This product is either not active, not published to the Online Store, or does not have any zero price variants." %}
    {% break %}
  {% endif %}

  {% log zero_price_variants: zero_price_variants %}

  {% if cache_alert_seconds > 0 %}
    {% comment %}
      -- check to see if this task has already alerted on this product in the cache period
    {% endcomment %}

    {% assign cache_key = "mechanic-monitor-zero-price-variants-" | append: product.id %}

    {% assign cached_value = cache[cache_key] %}

    {% if cached_value == "1" %}
      {% log "This task has previously alerted on this product and we're still in the cache period." %}
      {% break %}
    {% endif %}

    {% action "cache", "setex", cache_key, cache_alert_seconds, "1" %}
  {% endif %}

  {% comment %}
    -- send email alert
  {% endcomment %}

  {%- capture alert_email_subject -%}
    Zero price variants found on product "{{ product.title }}"
  {%- endcapture -%}

  {%- capture alert_email_body -%}
    <p>The following variants have a price of zero on {{ product.title }}, which is active and published to the Online Store.</p>

    <ul>
    {% for variant in zero_price_variants %}
      {%- capture title -%}
        {{ product.title }}{% if variant.title != "Default Title" %} - {{ variant.title }}{% endif %}{% if variant.sku %} ({{ variant.sku }}){% endif %}
      {%- endcapture -%}
      <li>
      {% if event.preview %}
        {{ title }}
      {% else %}
        <a href="{{ shop.admin_url }}products/{{ product.id }}/variants/{{ variant.id }}">{{ title }}</a>
      {% endif %}
      </li>
    {% endfor %}
    </ul>

    <p>- Mechanic for {{ shop.name }}</p>
  {%- endcapture -%}

  {% action "email" %}
    {
      "to": {{ alert_email_recipients | json }},
      "subject": {{ alert_email_subject | json }},
      "body": {{ alert_email_body | json }},
      "reply_to": {{ shop.customer_email | json }},
      "from_display_name": {{ shop.name | json }}
    }
  {% endaction %}
{% endif %}