Setting Field Values Programmatically in Hyva Checkout

On Checkout 3.x, the address forms keep re-emitting form:billing:updated and form:shipping:updated as deprecated legacy hooks, and value changes made there still reach the form. For new code, use the form:*:magewire hooks, which have no address type in their name. Register the modifier on the address form you want to change instead (EavAttributeBillingAddressForm or EavAttributeShippingAddressForm, see Entity Form Modifiers):

• form:loaded:magewire: fires once per request after the field values are loaded, before they sync to the frontend. Use it to set initial values or values derived from other fields.
• form:updated:data:<field>:magewire: fires when a specific field has changed, for example form:updated:data:country_id:magewire.
• form:updated:data:magewire: fires when any form field has changed.
• form:submitting:magewire: fires on form submission, before validation and saving.

If you need to modify fields on both forms, register the modifier on both forms.

Hyva Checkout fires separate update hooks depending on which address form was submitted. Pick the hook that matches the form whose fields you want to modify:

• form:billing:updated: Fires after the billing address form is submitted. Use this hook to set or clear billing address fields.
• form:shipping:updated: Fires after the shipping address form is submitted. Use this hook to set or clear shipping address fields.

Register your callback on the correct hook for the address type you are modifying. If you need to modify fields on both forms, register separate listeners for each hook.

On Checkout 3.x, the modifier listens on form:loaded:magewire and form:updated:data:country_id:magewire:

<?php

namespace Hyva\Example\Model\FormModifier;

use Hyva\Checkout\Model\Form\EntityFormInterface;
use Hyva\Checkout\Model\Form\EntityFormModifierInterface;

class ConditionalFieldValueModifier implements EntityFormModifierInterface
{
    public function apply(EntityFormInterface $form): EntityFormInterface
    {
        // Apply on every request once the loaded values are in the form
        $form->registerModificationListener(
            'empty-value-if-field-disabled-on-load',
            'form:loaded:magewire',
            [$this, 'emptyMyField']
        );

        // Apply again when the customer changes the country
        $form->registerModificationListener(
            'empty-value-if-field-disabled',
            'form:updated:data:country_id:magewire',
            [$this, 'emptyMyField']
        );

        return $form;
    }

    public function emptyMyField(EntityFormInterface $form, ...$rest)
    {
        // Get the current country value from the form data
        $country = $form->getField('country_id')->getValue();

        // Clear fields if the feature is not available for this country
        if (!$this->isExampleAvailable($country)) {
            // Clear the custom field using empty()
            $form->getField('my_field')->empty();

            // Set another field to a fallback value using setValue()
            $form->getField('other_field')->setValue('nope');
        }
    }

    private function isExampleAvailable(string $country): bool
    {
        // Business logic to determine feature availability by country
        return in_array($country, ['US', 'CA', 'GB']);
    }
}

The apply() method registers emptyMyField on both hooks. On every request, and again when the customer changes the country, the callback reads the selected country_id, checks availability, and either clears my_field with empty() or sets other_field to a fallback value with setValue().

On Checkout 1.x, the modifier listens on form:billing:updated:

<?php

namespace Hyva\Example\Model\FormModifier;

use Hyva\Checkout\Model\Form\EntityFormInterface;
use Hyva\Checkout\Model\Form\EntityFormModifierInterface;

class ConditionalFieldValueModifier implements EntityFormModifierInterface
{
    public function apply(EntityFormInterface $form): EntityFormInterface
    {
        // Register callback for the billing address updated event
        $form->registerModificationListener(
            'empty-value-if-field-disabled',
            'form:billing:updated',
            [$this, 'emptyMyField']
        );

        return $form;
    }

    public function emptyMyField(EntityFormInterface $form)
    {
        // Get the current country value from the submitted form data
        $country = $form->getField('country_id')->getValue();

        // Clear fields if the feature is not available for this country
        if (!$this->isExampleAvailable($country)) {
            // Clear the custom field using empty()
            $form->getField('my_field')->empty();

            // Set another field to a fallback value using setValue()
            $form->getField('other_field')->setValue('nope');
        }
    }

    private function isExampleAvailable(string $country): bool
    {
        // Business logic to determine feature availability by country
        return in_array($country, ['US', 'CA', 'GB']);
    }
}

The apply() method registers emptyMyField as a listener on the form:billing:updated hook. When billing address data is submitted, the callback reads the selected country_id, checks availability, and either clears my_field with empty() or sets other_field to a fallback value with setValue().

On Checkout 3.x, the form:*:magewire hooks run inside the form component and sync every value change to the component's data property. The data property is what the frontend shows and what the form saves, so changes made in these hooks persist.

The form:*:updated hooks execute after user input has been received and validated during form processing. At that point in the lifecycle, field values reflect the user's submitted data, the form state is stable, and programmatic changes will persist through the rest of the submission process.

Hooks like form:build run during initial form construction, before any user input is available. That is why value changes made in form:build have no effect: the form overwrites them with user-submitted data later in the lifecycle.

On Checkout 3.x, form:loaded:magewire fires on every request, including the initial page load, after the field values are loaded and before they sync to the frontend. Use it to set initial field values.

Because the hook also fires on every later request, only fill a field that is still empty, or you overwrite what the customer entered:

$form->registerModificationListener(
    'setMyFieldDefault',
    'form:loaded:magewire',
    function (AbstractEntityForm $form, ...$rest) {
        $form->modifyField('my_field', function (EntityFieldInterface $field) {
            // Only fill an empty field, so the customer's input is kept.
            if (! $field->hasValue()) {
                $field->setValue('my default');
            }
        });
    }
);

The form:*:updated hooks do not fire during the initial checkout page load (the "preceding request" in Magewire terminology). These hooks only fire in response to actual value submissions.

If you need to set specific field values before the customer interacts with the checkout form, use Magento-level mechanisms instead:

• Magento plugins: Intercept address loading methods to modify data before it reaches the Hyva Checkout form
• Event observers: Listen to Magento address-related events to modify values at the data layer
• Customer data providers: Customize the data source that feeds the form's initial values

These Magento-level approaches modify data before the Hyva Checkout form is constructed, so the form renders with your desired initial values already in place.