Modify fields with the PSR-14 event

This guide shows the legacy way of overriding single field values — the ModifyArrayRecursiveToArrayEvent. It is deprecated and kept for backwards compatibility; prefer normalizers or field value transformers for new code.

Why it is deprecated

The event predates the normalizer registry. It runs per field on every record conversion, carries ContentBlocks internals in its payload, and cannot express value-type dispatch cleanly. The modern equivalents:

Legacy (event)	Modern
Override by field name	Field value transformer (strings)
Override by value type	Custom normalizer
Whole-block post-processing	headless.php

The event keeps firing with its original payload until the next minor release; listeners continue to work unchanged until then.

The listener

<?php

declare(strict_types=1);

namespace MyVendor\MyExtension\EventListener;

use Netzbewegung\NbHeadlessContentBlocks\Event\ModifyArrayRecursiveToArrayEvent;
use TYPO3\CMS\Core\Attribute\AsEventListener;

#[AsEventListener]
final class MyCustomListener
{
    public function __invoke(ModifyArrayRecursiveToArrayEvent $event): void
    {
        // Custom handling by field name (column!)
        if ($event->getKey() === 'tx_my_vendor_field_name') {
            $processedValue = strtoupper((string)$event->getValue());
            $event->setProcessedValue($processedValue);
        }

        // Custom handling for all text fields
        if (
            $event->getTcaFieldDefinition() !== null
            && $event->getTcaFieldDefinition()->fieldType instanceof \TYPO3\CMS\ContentBlocks\FieldType\TextFieldType
        ) {
            $event->setProcessedValue(strtoupper((string)$event->getValue()));
        }
    }
}

Semantics:

getKey() is the database column (pre identifier mapping) — tx_my_vendor_field_name, not my_field.
setProcessedValue() marks the field as handled; the value lands in the JSON under the mapped field identifier.
Unhandled fields fall through to the normal conversion.
The event fires for every field of every record — return fast.

Migration

Replace setProcessedValue($value) calls with a transformer (string values) or normalizer (everything else). The migrated code is smaller, testable in isolation, and independent of ContentBlocks internals.