OrderLineDiscountDistributionStrategy

OrderLineDiscountDistributionStrategy

Determines the weight used to distribute (prorate) an order-level promotion discount across the OrderLines of an Order. The weights returned for all lines are fed into the prorate() helper, which splits the total order-level discount amount proportionally.

This makes it possible to control what happens to the distribution when a line is canceled or refunded. The default strategy gives a fully-canceled line (quantity 0) a weight of 0, so its share of the discount is redistributed across the remaining lines. A custom strategy can instead weight lines by their originally-placed quantity, keeping each surviving line's share stable when another line is refunded.

Example

// Keeps each surviving line's discount share stable when another line is// refunded, rather than redistributing the canceled line's share onto the// remaining lines. Suitable for unconditional order-level promotions where// the refunded amount must reconcile with the order total.export class PlacementStableDistributionStrategy    implements OrderLineDiscountDistributionStrategy {    getWeight(ctx: RequestContext, line: OrderLine, order: Order): number {        const placedQuantity = line.orderPlacedQuantity || line.quantity;        return line.unitPriceWithTax * placedQuantity;    }}

interface OrderLineDiscountDistributionStrategy extends InjectableStrategy {    getWeight(ctx: RequestContext, line: OrderLine, order: Order): number | Promise<number>;}

• Extends: InjectableStrategy

DefaultOrderLineDiscountDistributionStrategy

The default OrderLineDiscountDistributionStrategy. Weights each line by its current prorated line price (incl. tax) and assigns zero weight to fully-canceled lines (quantity 0). This reproduces Vendure's historical distribution behavior exactly.

This default is consistent with Vendure's promotion model, in which order-level promotions are re-evaluated on every order modification. When an order line is canceled, its share of an order-level discount is redistributed across the surviving lines.

Note that for unconditional order-level promotions (e.g. a flat "$50 off" with no minimum), this redistribution means a partial refund reduces the order total by more than the amount refunded, since the canceled line's discount share moves onto the retained lines. Stores that require the discount distributions to be immutable by refunds should provide a custom strategy that weights lines by their originally-placed quantity (see the example on OrderLineDiscountDistributionStrategy).

class DefaultOrderLineDiscountDistributionStrategy implements OrderLineDiscountDistributionStrategy {    getWeight(ctx: RequestContext, line: OrderLine, order: Order) => number;}

• Implements: OrderLineDiscountDistributionStrategy