Set default data on Symfony text field with data transformer - php

Question

I am working on a project to dynamically create Symfony forms on the fly using a yaml file (or any other data source that may return form description as an associative array). To handle things better I want to wrap Symfony's core types to work with a data object instead of scalar data. The data object will be a simple wrapper with getter-setter.
class SimpleFormData implements FormData {
/**
* #var mixed data
*/
private $data;
/**
* #param $data
*/
function __construct($data) {
$this->data = $data;
}
/**
* #return mixed
*/
public function getData() {
return $this->data;
}
/**
* #param mixed $data
*/
public function setData($data) {
$this->data = $data;
}
}
I started with writing a data transformer:
class SimpleFormDataTransformer implements DataTransformerInterface {
/**
* #param mixed $value The value in the original representation
* #return mixed The value in the transformed representation
* #throws TransformationFailedException When the transformation fails.
*/
public function transform($value) {
if(is_null($value)) {
return '';
}
if($value instanceof FormData) {
return $value->getData();
}
$actualType = is_object($value) ? 'an instance of class '.get_class($value) : ' a(n) '.gettype($value);
$message = sprintf("Expected argument of type MyApp\\FormBundle\\FormData\\FormData, got %s", $actualType);
throw new TransformationFailedException($message);
}
/**
* #param mixed $value The value in the transformed representation
* #return mixed The value in the original representation
* #throws TransformationFailedException When the transformation fails.
*/
public function reverseTransform($value) {
return new SimpleFormData($value);
}
}
I created a custom TextType and set model transformer to it:
class TextType extends AbstractType {
public function buildForm(FormBuilderInterface $builder, array $options) {
$transformer = new SimpleFormDataTransformer();
$builder->addModelTransformer($transformer);
}
/**
* Returns the name of this type.
*
* #return string The name of this type
*/
public function getName() {
return 'form_bundle_type_core_text';
}
public function getParent() {
return 'text';
}
}
Everything works fine if I create a TextType and set data by calling setData method:
$form = $this->createForm(new TextType());
$form->setData(new SimpleFormData("test"));
If I try passing default data, I get an error:
$form = $this->createForm(new TextType(), new SimpleFormData("test"));
The error thrown says:
The form's view data is expected to be an instance of class
MyApp\FormBundle\Model\SimpleFormData, but is a(n) string. You can
avoid this error by setting the "data_class" option to null or by
adding a view transformer that transforms a(n) string to an instance
of MyApp\FormBundle\Model\SimpleFormData.
I certainly don't want viewData to be of type SimpleFormData (hence the transformer). Also, I haven't set data_class, Symfony's Form class picks data class from the passed data object.
I have two questions:
What should I do to be able to pass default data?
Why Symfony expects viewData to be of type data_class? My understanding was that modelData should be of type data_class and not viewData.