How to avoid duplicates on ManyToMany relation with Doctrine2 and Zend Framework2? - orm

Question

The objective is to have 2 entity Article and Tag, with a many to many relation where the tags in Tag Table remain unique even if declare the same tag for other article.
I try to explain better with code:
Article Entity:
/**
* #ORM\Entity
* #ORM\Table(name="articles")
*/
class Article {
/**
* #ORM\Id #ORM\GeneratedValue(strategy="AUTO") #ORM\Column(type="integer")
* #var int
*/
protected $id;
/**
* #ORM\Column(type="string")
* #var string
*/
protected $name;
/**
* #ORM\ManyToMany(targetEntity="Tag\Entity\Tag",inversedBy="platforms",cascade={"persist","remove"})
*
* #return Tag[]
*/
protected $tags;
public function __construct() {
$this->tags = new ArrayCollection();
}
public function setId($id) {
$this->id = $id;
}
public function getId() {
return $this->id;
}
public function setName($name) {
$this->name = $name;
}
public function getName() {
return $this->name;
}
public function setTags($tags){
$this->tags = $tags;
}
public function setTagsFromArray(array $tags){
foreach($tags as $tag){
$this->tags->add(new Tag($tag));
}
}
/**
* Return the associated Tags
*
* #param boolean $getOnlyTagsName [optional] If set to true return a simple array of string (tags name).
* If set to false return array of Tag objects.
*
* #return Tag[]|string[]
*/
public function getTags($getOnlyTagsName=false) {
if ($getOnlyTagsName){
return array_map(function($i) { return $i->getName(); }, $this->tags->toArray());
}
return $this->tags;
}
public function addTags($tags) {
foreach($tags as $tag){
$this->tags->add($tag);
}
}
public function removeTags($tags) {
foreach ($tags as $tag){
$this->tags->removeElement($tag);
}
}
}
Tag Entity:
/**
* #ORM\Entity
* #ORM\Table(name="tags")
* ORM\HasLifecycleCallbacks // NOT USED
*/
class Tag {
/**
* #ORM\Id #ORM\Column(type="integer") #ORM\GeneratedValue
* #var int
*/
protected $id;
/**
* #ORM\Column(type="string",unique=true)
* #var string
*/
protected $name;
/**
* #ORM\Column(type="datetime",name="created_at")
* #var datetime
*/
protected $createdAt;
/**
* #ORM\Column(type="datetime",name="updated_at")
* #var datetime
*/
protected $updatedAt;
/**
* #ORM\ManyToMany(targetEntity="Article\Entity\Article", mappedBy="tags")
* var Tag[]
*/
protected $platforms;
/**
* Constructor
*
* #param string $name Tag's name
*/
public function __construct($name = null) {
$this->setName($name);
$this->setCreatedAt(new DateTime('now'));
$this->setUpdatedAt(new DateTime('now'));
}
/**
* Avoid duplicate entries.
*
* ORM\PrePersist // NOT USED
*/
public function onPrePersist(LifecycleEventArgs $args) {
}
/**
* Avoid duplicate entries.
*
* ORM\PreUpdate // NOT USED
*/
public function onPreUpdate(PreUpdateEventArgs $args) {
}
public function setId($id) {
$this->id = $id;
}
/**
* Returns tag's id
*
* #return integer
*/
public function getId() {
return $this->id;
}
/**
* Sets the tag's name
*
* #param string $name Name to set
*/
public function setName($name) {
$this->name = $name;
}
/**
* Returns tag's name
*
* #return string
*/
public function getName() {
return $this->name;
}
public function setCreatedAt(DateTime $date) {
$this->createdAt = $date;
}
public function getCreatedAt() {
return $this->createdAt;
}
public function setUpdatedAt(DateTime $date) {
$this->updatedAt = $date;
}
public function getUpdatedAt() {
return $this->updatedAt;
}
}
Then I have the Article Form (with Article Fieldset) where there is a tagsinput (jquery plugin) element. So the form post it's like:
object(Zend\Stdlib\Parameters)[151]
public 'security' => string 'dc2a6ff900fbc87933e07bd35ef36709...' (length=65)
public 'article' =>
array (size=3)
'id' => string '' (length=0)
'name' => string 'Article 1' (length=13)
'tags' =>
array (size=3)
0 => string 'tag1' (length=3)
1 => string 'tag2' (length=4)
2 => string 'tag3' (length=7)
public 'submit' => string 'Add' (length=8)
A the first insert all goes well, but when I try to insert another article with one of the article1 tags I get the error:
An exception occurred while executing 'INSERT INTO tags (name, created_at, updated_at) VALUES (?, ?, ?)' with params ["tag2", "2014-04-26 22:05:37", "2014-04-26 22:05:37"]:
SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry 'tag2' for key 'UNIQ_6FBC94265E237E06'
I know that I can use prePersist and preUpdate event listner, but I made some test but I don't know how to use Unit Of Work to avoid duplicates.

Answer 1

You can't have the Tag's name property (and database field) defined as unique. You'll have the Integrity constraint violation every time you set a new tag with a previously picked tag name. You just need to control that a name is not picked for a tag related to the same article.
You could add a Zend\Validator\Db\NoRecordExists validator to the tagsinput element to achieve that. It would be something like that:
$tagsinput->getValidatorChain()->addValidator(
new NoRecordExists( array(
'adapter' => $this->getServiceManager()->get( 'Zend\Db\Adapter\Adapter' ),
'table' => 'tag',
'field' => 'name',
'message' => 'The tag name already exists',
'exclude' => 'article_id = ' . $article->getId(),
) );
--
Edit:
This solution won't work if there are more than one tag, when tagsinput's value will be an array. You could iterate through the array to validate each tag, but it's not an efficient solution, it would execute N queries. You could implement a similar validator which accepts a where clause like TAG_NAME IN ( 'tag1', 'tag2', 'tag3' )
--
Note that this validator doesn't work with Doctrine2; table, field and exclude parameters have database values.
This should work when adding tags to an existing article. To validate that a new article doesn't have duplicated tags, you could do it client side or you could write your own validator.