Dynamic values

How to leverage dynamic values for a rule's conditions.

The value key of a condition can be dynamic. This is extremely useful when the value to be compared with the field value isn't known in advance or is based on the value of another field.

To leverage dynamic values for a rule's conditions you need to use the double curly brackets notation {{<reference_field>}} where <reference_field> is the resource's field (expressed in dot notation) that will be used as a variable to calculate the value. Some basic operators that can be applied to the reference field are also provided (as shown in the examples below):

Operator	Field type	Description	Example value
min	Number	The smallest of the reference field values is used as the condition's value.	"{{min(order.line_items.shipment.available_shipping_methods.price_amount_cents)}}"
max	Number	The biggest of the reference field values is used as the condition's value.	"{{max(order.line_items.compare_at_amount_cents)}}"
avg	Number	The average of the reference field values is used as the condition's value.	"{{avg(order.line_items.sku.inventory.levels.quantity))}}"

The reference field type must be consistent with the matcher used against the field and value. Given the currently available functions, if you want to add one of the operators above, the reference field type must be numeric.

Examples

Direct dynamic value

The following condition uses a dynamic value to check if an order's line items have the same unit amount and compare-at amount (i.e. the actual selling price is equal to the full price displayed to the customer with a strikethrough — that is to say, the items is not in sale):

"conditions": [
  {
    "field": "order.line_items.unit_amount_cents",
    "matcher": "eq",
    "value": "{{order.line_items.compare_at_amount_cents}}"
  }
]

Dynamic value with operator

The following condition uses a dynamic value with the min operator to target the shipment line items associated with the cheapest shipping method among the ones available for an order's shipments:

"conditions": [
  {
    "field": "order.line_items.shipment.cost_amount_cents",
    "matcher": "eq",
    "value": "{{min(order.line_items.shipment.available_shipping_methods.price_amount_cents)}}"
  }
]