Discount Type Forms

Registering a custom discount type is a core concern, covered in Extending Discounts. This page covers only the panel-specific step: giving that type an edit form in the Discounts section, instead of the panel’s raw JSON fallback.

The `DiscountTypeForm` contract

namespace Lunar\Panel\Contracts;

use Lunar\Core\Models\Currency;

interface DiscountTypeForm
{
    /** Vue component id, resolved through the panel's component registry. */
    public function component(): string;

    /** @return array<int, string> */
    public function targetBuckets(): array;

    /** @param array<string, mixed> $data @return array<string, mixed> */
    public function toForm(array $data): array;

    /** @param array<string, mixed> $data @return array<string, mixed> */
    public function toStorage(array $data): array;

    /** @return array<string, mixed> */
    public function rules(): array;

    public function summary(array $data, ?Currency $currency): ?string;
}

component() — the Vue component id that renders the type’s configuration fields, resolved the same way a widget or slot component is.
targetBuckets() — which of the four targeting buckets (limitation, exclusion, condition, reward) this type reads, driving which “Applies to” blocks the edit page shows. A type that discounts the whole cart or an entire shipping method rather than individual lines returns an empty array — ShippingDiscount, for example, targets nothing.
toForm(array $data) — decodes the discount’s stored data payload for editing (minor currency units to decimals, and so on).
toStorage(array $data) — the inverse: encodes the edited form values back into the shape stored in data.
rules() — validation rules for the type’s own data.* fields, keyed without the data. prefix.
summary(array $data, ?Currency $currency) — a one-line description of the discount’s effect for the discounts list ("15% off", "Buy 2, get 1"). Return null when the type cannot summarise itself from data alone; the list falls back to the type’s own name.

Scale money through Currency::decimal_places (via PriceCalculator), never a hardcoded factor — the same rule that applies to every price-handling code path in Lunar.

Registering a form

Map the discount type class to its form class from the owning Section:

public function discountTypeForms(): array
{
    return [
        MyCustomDiscountType::class => MyCustomDiscountTypeForm::class,
    ];
}

A first-party reference implementation, PercentageOffForm, shows the shape for a type with no money scaling to do:

namespace Lunar\Panel\Support\DiscountTypeForms;

use Lunar\Core\Models\Currency;
use Lunar\Panel\Contracts\DiscountTypeForm;

class PercentageOffForm implements DiscountTypeForm
{
    public function component(): string
    {
        return 'PercentageOffForm';
    }

    public function targetBuckets(): array
    {
        return ['limitation', 'exclusion'];
    }

    public function toForm(array $data): array
    {
        return ['percentage' => (float) ($data['percentage'] ?? 0)];
    }

    public function toStorage(array $data): array
    {
        return ['percentage' => (float) ($data['percentage'] ?? 0)];
    }

    public function rules(): array
    {
        return ['percentage' => ['required', 'numeric', 'min:0', 'max:100']];
    }

    public function summary(array $data, ?Currency $currency): ?string
    {
        $percentage = (float) ($data['percentage'] ?? 0);

        if (! $percentage) {
            return null;
        }

        return __('panel::discounts.summary_percentage_off', [
            'percentage' => rtrim(rtrim(number_format($percentage, 2, '.', ''), '0'), '.'),
        ]);
    }
}

The JSON-editor fallback

A discount type with no registered form is not hidden — it falls back to Lunar\Panel\Support\DiscountTypeForms\RawDataForm, a plain JSON editor over the type’s stored data, with every target bucket shown. This is what keeps a panel-unaware type (one written only against the Filament admin’s LunarPanelDiscountInterface, for example) editable in the panel instead of disappearing from it. RawDataForm::summary() always returns null, since the panel has no idea what an arbitrary payload means.

A discount type can implement both the Filament Lunar\Admin\Base\LunarPanelDiscountInterface and the panel’s DiscountTypeForm to serve both admins from one class. Neither is required by the other.

For registering the discount type itself — Discounts::addType(), AbstractDiscountType, and apply() — see Extending Discounts.

​The DiscountTypeForm contract

​Registering a form

​The JSON-editor fallback

The `DiscountTypeForm` contract

Registering a form

The JSON-editor fallback