Google Tag Shopify Purchase

<!-- Google tag (gtag.js) -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-EXAMPLE"></script>
<script>
  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments);}
  gtag('js', new Date());
  gtag('config', 'G-EXAMPLE');
{% if first_time_accessed %}
gtag("event", "purchase", {
    transaction_id: "{{ checkout.order_id }}",
    value: {{ total_price | times: 0.01 }},
    tax: {{ tax_price | times: 0.01 }},
    shipping: {{ shipping_price | times: 0.01 }},
    currency: "{{ checkout.currency }}",
    items: [
     {% for line_item in line_items %}
     {
      item_id: "{{ line_item.product_id }}",
      item_name: "{{ line_item.title | remove: "'" | remove: '"' }}",
      currency: "{{ checkout.currency }}",
      price: {{ line_item.original_price | times: 0.01 }},
      quantity: {{ line_item.quantity }}
    },
    {% endfor %}
    ]
});
{% endif %}
</script>

For the transaction_id would it be better to use the order.id? It is possible for a customer to place an order and for the order object to be missing order_number and name at this point. They are then added later by Shopify (when the order processing is complete). But since we only have chance to track when the user views the page, that order will not come through to GA4.

It’s based on Shopify’s own recommendation for conversion tracking on the order status page. See https://help.shopify.com/en/manual/orders/status-tracking/customize-order-status/add-conversion-tracking

So if their documentation isn’t right, you might want to customize it, but it works for my Shopify store.

Yeah I don't think that help page is right any more. Check your store orders for anything with a confirmation number in the order activity and then check to see if that order was tracked by GA4.

Mine all have an order number, but feel free to customize as you need.