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title: Constructing a Rule

Constructing a Rule

A rule has two main parts: conditions and a fee. When calculateServiceFees() is called, it assesses each rule in relation to the specified order. When a rule is assessed, if the conditions are met, the fee is included in the API's response.

Conditions

Conditions can be either a single condition or a condition tree.

A single condition evaluates a specific field in the order. For example, it could check if the value of the field is greater than a certain number.

A condition tree contains two conditions and an operator. The conditions can each be either a single condition or a condition tree. There are two operator values:

• "AND": Both conditions must be met for the condition tree to be considered met.
• "OR": At least one of the conditions must be met for the condition tree to be considered met.

Condition tree example

Conditions

For the service fee to be applied, we would need to satisfy these conditions:

• The price subtotal is greater than 50
  AND
• Either:
  • Delivery type is "DELIVERY"
    OR
  • Order is made in the mobile app

Example: Conditions are met

We have the following values:

• Subtotal is 70
• Delivery type is "DELIVERY"
• Order is "WEBSITE"

In this case, the conditions are met, because the subtotal is greater than 50 and the delivery type is "DELIVERY". It doesn't matter that the platform isn't "MOBILE_APP" because we only need that OR delivery type to be "DELIVERY".

Example: Conditions are not met

We have the following values:

• Subtotal is 30
• Delivery type is "DELIVERY"
• Order is "MOBILE_APP"

In this case, the conditions are not met, because even though the delivery type is "DELIVERY" and the platform is "MOBILE_APP", the subtotal is not greater than 50.

Fee

A fee is either a fixed amount or a percentage of the order's subtotal. It can also include tax.

If the conditions are met, the fee is calculated and applied when calculateServiceFees() is called.