Controller.php

<?php
class SomeClass
{
    public function someMethod()
    {
        $parametersFieldsForm = $form->create('parameters', null, [
            'compound' => true,
            'translation_domain' => false,
        ]);
        foreach ($parameters as $parameter) {
            $this->addFieldsFromParameter($parametersFieldsForm, $parameter, $parameter->getName());
        }
        $form->add($parametersFieldsForm);
    }
    protected function addFieldsFromParameter(FormBuilder $form, AbstractGeneratedStruct $struct, $baseFormName)
    {
        /** @var StructFieldGenerator $structFieldGenerator */
        $structFieldGenerator = $this->get('providr.struct_field_generator');
        /**
         * form part fields to be generated
         */
        if (strpos($baseFormName, '[')) {
            $formBaseNameParts = explode('[', $baseFormName);
            $fieldsForm = null;
            foreach ($formBaseNameParts as $index => $formBaseNamePart) {
                // first item is form, this is the default first form level that we don't care
                if ($index > 0) {
                    if (isset($fieldsForm)) {
                        $form->add($fieldsForm);
                        $form = $fieldsForm;
                    }
                    $fieldsForm = $form->create(str_replace(']', '', $formBaseNamePart), null, [
                        'compound' => true,
                        'label_attr' => [
                            'class' => 'hidden',
                        ],
                        'csrf_protection' => false,
                        'translation_domain' => false,
                    ]);
                }
            }
            foreach ($struct->getProperties() as $property) {
                $structFieldGenerator->addStructToForm($fieldsForm, $property, $this);
            }
            $form->add($fieldsForm);
        } else {
            $structFieldGenerator->addStructToForm($form, $struct, $this);
        }
    }
    /**
     * @Route("/formpart", name="admin_formpart", condition="request.isXmlHttpRequest()")
     * @Method({"GET"})
     */
    public function viewExecutionFormPartAction(Request $request)
    {
        $form = $this->createFormBuilder(null, [
            'csrf_protection' => false,
        ]);
        /** @var AbstractGeneratedStruct $struct */
        $this->addFieldsFromParameter($form, $struct, $request->query->get('field_name'));
        return new Response($this->renderView('...'), [
            'form' => $form->getForm()->createView(),
        ]);
    }
}

StructFieldGenerator.php

<?php
class StructFieldGenerator
{
    /**
     * @param FormBuilder $form
     * @param AbstractGeneratedStruct $struct
     * @param Controller $controller
     */
    public function addStructToForm(FormBuilder $form, AbstractGeneratedStruct $struct, Controller $controller)
    {
        $form->add($struct->getName(), $this->getFieldType($struct), $this->getFieldOptions($struct, $controller));
    }
}