Flow Form Framework: Persist form state on each page

form.yaml

type: 'Neos.Form:Form'
identifier: persist-test
renderables:
    -
        type: 'Neos.Form:Page'
        identifier: page1
        renderables:
            -
                type: 'Neos.Form:SingleLineText'
                identifier: name
                label: Name
                validators:
                    -
                        identifier: 'Neos.Flow:NotEmpty'
            -
                type: 'Neos.Form:MultiLineText'
                identifier: comment
                label: Comment
    -
        type: 'Your.Package:PersistPage'
        identifier: page2
        renderables:
            -
                type: 'Neos.Form:SingleLineText'
                identifier: foo
                label: singlelinetext1
                validators:
                    -
                        identifier: 'Neos.Flow:NotEmpty'
                properties:
                    placeholder: placey
                defaultValue: defaulty
    -
        type: 'Neos.Form:PreviewPage'
        identifier: previewpage1
        label: previewpage1

PersistPage.php

<?php
namespace Your\Package;

use Neos\Form\Core\Model\Page;
use Neos\Form\Core\Runtime\FormRuntime;

class PersistPage extends Page
{
    public function beforeRendering(FormRuntime $formRuntime)
    {
        // TODO persist $formRuntime->getFormState()->getFormValues()
    }


}

Settings.yaml

Neos:
  Form:
    presets:
      <PRESET_NAME>:
        formElementTypes:
          'Your.Package:PersistPage':
            superTypes:
              'Neos.Form:Page': true
            renderingOptions:
                # OPTIONAL: Use the default page's template
              templatePathPattern: 'resource://Neos.Form/Private/Form/Page.html'
            implementationClassName: Your\Page\PersistPage

Don't forget to replace PRESET_NAME with your preset (or "default" to make it available to all sub-presets) and Your.Package with your package key