Symfony2 data transformer string to entity (reverseTransform) - symfony

Question

I am pretty new to Symfony and hope someone can help me. I have an entity called Material and an associated entity called MaterialKeyword, which are basically tags. I am displaying the keywords comma delimited as a string in a text field on a form. I created a data transformer to do that. Pulling the keywords from the database and displaying them is no problem, but I have a problem with the reversTransform function when I want to submit existing or new keywords to the database.
Material class (MaterialKeyword):
/**
* #Assert\Type(type="AppBundle\Entity\MaterialKeyword")
* #Assert\Valid()
* #ORM\ManyToMany(targetEntity="MaterialKeyword", inversedBy="material")
* #ORM\JoinTable(name="materials_keyword_map",
* joinColumns={#ORM\JoinColumn(name="materialID", referencedColumnName="materialID", nullable=false)},
* inverseJoinColumns={#ORM\JoinColumn(name="keywordID", referencedColumnName="id", nullable=false)})
*/
public $materialkeyword;
/**
* Constructor
*/
public function __construct()
{
$this->MaterialKeyword = new ArrayCollection();
}
/**
* Set materialkeyword
*
* #param array $materialkeyword
*
*/
public function setMaterialkeyword(MaterialKeyword $materialkeyword=null)
{
$this->materialkeyword = $materialkeyword;
}
/**
* Get materialkeyword
*
* #Assert\Type("\array")
* #return array
*/
public function getMaterialkeyword()
{
return $this->materialkeyword;
}
Here is my code from the data transformer:
This part is working:
class MaterialKeywordTransformer implements DataTransformerInterface
{
/**
* #var EntityManagerInterface
*/
private $manager;
public function __construct(ObjectManager $manager)
{
$this->manager = $manager;
}
/**
* Transforms an object (materialkeyword) to a string.
*
* #param MaterialKeyword|null $materialkeyword
* #return string
*/
public function transform($material)
{
$result = array();
if (null === $material) {
return '';
}
foreach ($material as $materialkeyword) {
$result[] = $materialkeyword->getKeyword();
}
return implode(", ", $result);
}
This part is not working:
/**
* Transforms a string (keyword) to an object (materialkeyword).
*
* #param string $materialkeyword
* #return MaterialKeyword|null
* #throws TransformationFailedException if object (materialkeyword) is not found.
*/
public function reverseTransform($keywords)
{
// no keyword? It's optional, so that's ok
if (!$keywords) {
return;
}
$repository = $this->manager
->getRepository('AppBundle:MaterialKeyword');
$keyword_array = explode(", ", $keywords);
foreach($keyword_array as $keyword){
$materialkeyword = new MaterialKeyword();
$keyword_entry = $repository->findBy(array('keyword' => $keyword));
if(array_key_exists(0, $keyword_entry)){
$keyword_entry_first = $keyword_entry[0];
}else{
$keyword_entry_first = $keyword_entry;
}
if (null === $keyword_entry_first) {
throw new TransformationFailedException(sprintf('There is no "%s" exists',
$keywords
));
}
$materialkeyword->setKeyword($keyword_entry_first);
}
return $materialkeyword;
}
There will be several keywords, so how do I store them. I tried Arrays and ArrayCollections (new ArrayCollection()) without any success.
The error that I am getting currently with the code above:
Catchable Fatal Error: Argument 1 passed to Doctrine\Common\Collections\ArrayCollection::__construct() must be of the type array, object given, called in /.../vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php on line 605 and defined

Answer 1

TL;DR;
Your reverseTransform function should return an array containing zero or n MaterialKeyword.
It should not return a single MaterialKeyword object because the reverse transformation of MaterialKeyord[] --> string is not string --> MaterialKeyword, it is string --> MaterialKeyword[].
Thinking about this, the doctrine ArrayCollection exception you have make sense as it is trying to do new ArrayCollection(/** Single MaterialKeyword object */) instead of new ArrayCollection(/** Array of MaterialKeyword objects */).

Answer 2

From what you're telling I assume that Material and MaterialKeyword are connected by a ManyToMany association, in which case each Material has an array of MaterialKeyword objects associated to it.
Which means, that your Data Transformer should work with arrays as well, but you're only working with single objects.
Specifically, reverseTransform should return an array of MaterialKeyword objects, whereas you're only returning one (the last one handled in the loop.)
Another issue is that your method created new objects every time, even though $repository->findBy(...) would already return a MaterialKeyword instance. Creating a new object would cause that entry to be copied instead of simply used.
So the correct method might look like this:
public function reverseTransform($keywords)
{
// no keyword? It's optional, so that's ok
if (!$keywords) {
return array();
}
$repository = $this->manager
->getRepository('AppBundle:MaterialKeyword');
$keyword_array = explode(", ", $keywords);
$result_list = array(); // This will contain the MaterialKeyword objects
foreach($keyword_array as $keyword){
$keyword_entry = $repository->findOneBy(array('keyword' => $keyword));
if (null === $keyword_entry) {
throw new TransformationFailedException(sprintf('There is no "%s" exists',
$keyword
));
}
$result_list[] = $keyword_entry;
}
return $result_list;
}

Answer 3

#Hanzi put me on the correct track. It has to be an array of MaterialKeywords objects.
Here is my final working code in class MaterialKeywordTransformer:
/**
* Transforms a string (keyword) to an object (materialkeyword).
*
* #param string $materialkeyword
* #return MaterialKeyword|null
* #throws TransformationFailedException if object (materialkeyword) is not found.
*/
public function reverseTransform($keywords)
{
// keyword are optional, so that's ok
if (!$keywords) {
return;
}
$repository = $this->manager
->getRepository('AppBundle:MaterialKeyword');
$repository_m = $this->manager
->getRepository('AppBundle:Material');
$keyword_array = explode(", ", $keywords);
foreach($keyword_array as $keyword){
$materialkeyword = new MaterialKeyword();
$materialkeyword->setKeyword($keyword);
if($this->opt["data"]->getMaterialID() !== null) {
$materialkeyword->setMaterialID($this->opt["data"]->getMaterialID());
} else {
$material = $repository_m->findOne();
$materialID = $material[0]->getMaterialID();
$materialkeyword->setMaterialID($materialID);
}
$materialkeywords[] = $materialkeyword;
if (null === $keywords) {
throw new TransformationFailedException(sprintf('There is no "%s" exists',
$keywords
));
}
}
return $materialkeywords;
}