silverstripe-framework/tests/php/Forms/AssetFieldTest/TestForm.php

<?php

namespace SilverStripe\Forms\Tests\AssetFieldTest;

use SilverStripe\Dev\TestOnly;
use SilverStripe\Forms\AssetField;
use SilverStripe\Forms\FieldList;
use SilverStripe\Forms\Form;
use SilverStripe\Forms\FormAction;
use SilverStripe\Forms\RequiredFields;

class TestForm extends Form implements TestOnly
{

    public function getRecord()
    {
        if (empty($this->record)) {
            $this->record = TestObject::get()
                ->filter('Title', 'Object1')
                ->first();
        }
        return $this->record;
    }

    /**
     * @skipUpgrade
     * @param null   $controller
     * @param string $name
     */
    public function __construct($controller = null, $name = 'Form')
    {
        if (empty($controller)) {
            $controller = new TestController();
        }

        $fields = new FieldList(
            AssetField::create('File')
                ->setFolderName('MyFiles'),
            AssetField::create('Image')
                ->setAllowedFileCategories('image/supported')
                ->setFolderName('MyImages'),
            AssetField::create('NoRelationField')
                ->setFolderName('MyDocuments')
        );
        $actions = new FieldList(
            new FormAction('submit')
        );
        $validator = new RequiredFields();

        parent::__construct($controller, $name, $fields, $actions, $validator);

        $this->loadDataFrom($this->getRecord());
    }

    public function submit($data, Form $form)
    {
        $record = $this->getRecord();
        $form->saveInto($record);
        $record->write();
        return json_encode($record->toMap());
    }
}