How to Write Custom Rules Safely

DropStream's rules engine is a powerful tool that enables you define and automate custom integration behaviors. Like all powerful tools, it should be used safely.

When writing a custom rule, you can use conditional statements for testing purposes, so that your new rules do not affect your live orders until testing is complete. We call this approach safe-ifying.

The following is an example of a when statement that safely tests a custom rule behavior. This behavior should not yet be applied to live orders; for now, it should only run when certain test conditions are satisfied.

when
  order.shipping_first_name starts_with "testrule"
then
  #Custom code here
end

This when statement should be placed immediately after a rule definition, i.e. rule name. The test code will only run when the first name of the shipping recipient begins with "testrule", e.g., testrule-1, testrule-2, etc. 

When the testing of the custom rules is complete, the when statement and its corresponding then and end statements can be removed, leaving only the main code.

Here's another example of safe-ifying a custom rule for testing:

rule "Testing Safe-ify"
  when
    order.shipping_first_name starts_with "testrule"
  then
    for order_items in order
      when
        order has any order_items with (order_item.sku starts_with "SKU-C")
      then
        add 1.0 item to order_items in order
          set item.sku to "SKU-A"
        end
        add 1.0 item to order_items in order
          set item.sku to "SKU-B"
        end
      end
    end
  end
end

Note: Be safe while working with the rule engine, and use this safe-ify technique to protect your current integration process while testing new rules.