Environment variables

A task's Liquid code always has access to a set of environment variables, defined by Mechanic.

Environment variables may be reassigned as needed. (When preparing a task preview, this may be a necessary technique.) To learn more, see Stub data.

Variable	Contents
shop	An object containing Shopify's REST representation of the current Shopify store
event	An object containing information about the current event
cache	The current store's Mechanic cache object, supporting lookups for cached values
globals	The current store's visible globals, for reusable JSON configuration
secrets	The current store's write-only secrets, returned as opaque references unless used by a supported action or signing filter
task	An object containing information about the current task
options	An object containing task options, configured by the user

The [Shopify variables](environment-variables.md#shopify-variables) available to tasks always contain data drawn from the event itself. If a task has a offset event subscription, this data may be outdated by the time the task runs.

To reload the data in a Shopify variable, use something like this:

{% unless event.preview %}
  {% assign customer = customer.reload %}
{% endunless %}

Remember, Mechanic does not permit access to the Shopify API during event preview. Using this unless statement ensures that reloading only happens during a live event.

Event subject variables

When a task is actually invoked for an event, it may have access to an additional variable, determined by the specific event it is responding to. When this is the case, the additional variable will be named after the event subject, and its contents will be established by the event's data. The name of this variable is communicated by the Mechanic task editor, based on the task's current subscriptions.

For example, a subscription to shopify/customers/create will make available a variable called customer. A subscription to shopify/products/update will expose a variable called product, etc.

Shopify variables

All Shopify events support an additional variable named after the event topic. For example, when a task responds to a shopify/customers/create event, it will have access to an additional variable named customer, containing the customer data contained in the event.

Shopify events always contain data from Shopify's REST representation of each resource; therefore, automatic Shopify variables always contain data from the REST representation as well. The best resource for the data available for each variable type is Shopify's REST Admin API reference.

Shopify variables in Mechanic do not necessarily contain the same attributes as Liquid variables used in Shopify (in places like themes or email templates) – even if they share the same name.

In Mechanic, Shopify variables always contain data from Shopify events, which are delivered to Mechanic via webhook. This means that Shopify variables always have the same data structure as Shopify webhooks, corresponding to Shopify's REST representation for this data.

For example, while Shopify themes support customer.name, Mechanic does not (because Shopify's REST representation of the customer resource does not contain a "name" property). On the other hand, Mechanic supports customer.created_at, while Shopify themes do not.