Formatting and Computed Fields

The Presenter has three primary mechanisms for shaping output values: compute, formatDate, and formatCurrency.

Computed fields

->compute(string $name, Closure $factory): self

Closure signature: fn(DataObject $dto, PresentationContext $ctx): mixed.

Presenter::for($product)
    ->compute('priceFormatted', fn ($p, $ctx) => wc_price($p->price))
    ->compute('isOnSale', fn ($p) => $p->salePrice > 0 && $p->salePrice < $p->price);

• The DTO type can be narrowed in the closure: fn (ProductDto $p) => ...
• The closure runs lazily — only invoked if the field name survives only() and hide() filters
• Computed fields can override DTO properties; if you compute('price', ...), the original price property value is replaced
• Use compute to call Secret::reveal() when you actually need the plaintext in output (auditable at the call site)

->compute('rawApiKey', fn ($p) => $p->apiKey?->reveal())

Date formatting

->formatDate(string $field, string $format, ?string $as = null): self

• Reads the named field, expects a DateTimeInterface
• Formats via DateTimeFormatter honoring the context's locale and timezone
• If $as is null, replaces the original field. Otherwise creates a new field under $as and leaves the original alone.

->formatDate('publishedAt', 'F j, Y')                      // replace
->formatDate('publishedAt', 'F j, Y', as: 'publishedDate') // add new field

PHP's DateTime::format() syntax applies. The locale affects month and day names (F, l, M, D).

Currency formatting

->formatCurrency(string $field, ?string $as = null, ?string $currency = null, bool $html = false): self

• Reads the named field, expects a numeric value (int or float)
• Formats via CurrencyFormatter — uses WooCommerce's wc_price() when WC is active and the $html flag is true; falls back to a plain locale-aware number-format otherwise
• $currency is a 3-letter ISO code ('USD', 'HUF', 'EUR'); when null, uses WooCommerce's default or the context locale's currency
• $html: true returns a string with WC's HTML wrapping (<span class="woocommerce-Price-amount">...</span>); false returns plain text

->formatCurrency('price')                                              // replace, plain
->formatCurrency('price', as: 'priceDisplay', currency: 'HUF')         // add new field
->formatCurrency('price', as: 'priceHtml', html: true)                 // WC HTML

Combining date and currency with computed fields

Presenter::for($order)
    ->context(PresentationContext::email(userId: $order->customerId))
    ->formatDate('createdAt', 'F j, Y', as: 'orderDate')
    ->formatCurrency('total', as: 'totalDisplay')
    ->compute('lineCount', fn ($o) => count($o->items))
    ->compute('subtotalDisplay', fn ($o) => wc_price($o->subtotal))
    ->only(['orderNumber', 'orderDate', 'totalDisplay', 'subtotalDisplay', 'lineCount'])
    ->toJson();

Presets for nested fields

->preset(string $field, Closure $renderer): self

Closure signature: fn(mixed $value, PresentationContext $ctx): mixed.

preset runs before the recursive render of nested values. Useful when you want to override how a nested DTO appears without subclassing its presenter.

->preset('billingAddress', fn ($address, $ctx) => [
    'line' => "{$address->city}, {$address->country}",
])

Working with collections

CollectionPresenter exposes the same fluent methods. Computed fields are evaluated per-DTO:

$rows = Presenter::forCollection($products)
    ->context(PresentationContext::admin())
    ->compute('priceFormatted', fn ($p) => wc_price($p->price))
    ->only(['id', 'title', 'priceFormatted'])
    ->toArray();

Common mistakes

• Expecting compute('foo', ...) to run when foo was hidden by hide('foo', ...) or excluded by only([...]) — closures are lazy; they don't fire when the output won't include the field
• Forgetting to add the computed name to only() — only(['id', 'price']) excludes a compute('priceFormatted', ...) because priceFormatted isn't in the whitelist
• Using formatCurrency on a non-numeric field — fails with type error in CurrencyFormatter. Use compute for non-trivial cases
• Locale not changing the output — make sure the PresentationContext carries the locale (PresentationContext::email(locale: 'hu_HU'))