doctrine2 insert arraycollection in database - php

Question

I am trying to insert an array collection in my database. The relation between the objects is ManyToMany . So i want to post a message and add some hashtags (not just one, a few for example stored in a Doctrine 2 array collection). There is no error, but the objects are not linked: (The tables messages and hastags both contain data, but the messages_hastags table is empty.
My code:
Message.php
/**
* #ORM\ManyToMany(targetEntity="Application\Entity\Hashtag", mappedBy="messages")
*/
private $hashtags;
public function __construct()
{
$this->hashtags = new ArrayCollection();
}
function getHashtags() {
return $this->hashtags;
}
function setHashtags($hashtags) {
$this->hashtags = $hashtags;
}
Hashtag.php
public function __construct()
{
$this->messages = new ArrayCollection();
}
/** #ORM\ManyToMany(targetEntity="Application\Entity\Message", inversedBy="hashtags") */
private $messages;
function getMessages() {
return $this->messages;
}
function setMessages($messages) {
$this->messages = $messages;
}
Controller.php
$hashtag_array = new \Doctrine\Common\Collections\ArrayCollection();
$hashtag_array->add(HASHTAG); //here is a for loop adding some entities
$newMessage = \Application\Entity\Message();
$newMessage->setHashtags($hashtag_array);
$em->persist($newMessage);
$em->flush();
The message will appear in the database but without the link to the hashtags.

Answer 1

Your mapping is seriously wrong.
Both the inversedBy and mappedBy fields are pointing to "hashtags". And one of them has even a typo (hastags).
In you message it should be mappedBy="messages".
You also need to always initialize your collections in the constructor!
So inside the Hashtag entity:
public function __construct()
{
$this->messages = new ArrayCollection();
}
I would suggest to first fix all this and then check if your issues are solved.
UPDATE
You cannot do:
$newMessage->setHashtags($hashtag_array);
Doctrine collections cannot be directly exchanged with an array like this.
You have to add proper setter and getter methods as written in the Doctrine 2 documentation chapter 8. Working with Associations. I would suggest doing some documentation reading before you continue working with Doctrine. To make these things work it is important to understand the Doctrine internals.
This is what it should look like inside your Message resource:
/**
* Get hashtags
*
* #return Collection
*/
public function getHashtags()
{
return $this->hashtags;
}
/**
* Add hashtag.
*
* #param Hashtag $hashtag
* #return self
*/
public function addHashtag(Hashtag $hashtag)
{
$this->hashtags->add($hashtag);
return $this;
}
/**
* Add hashtags.
*
* #param Collection|array $hashtags
* #return self
*/
public function addHashtags($hashtags)
{
foreach($hashtags as $hashtag){
$this->addHashtag($hashtag);
}
return $this;
}
/**
* Remove hashtag.
*
* #param Hashtag $hashtag
* #return self
*/
public function removeHashtag(Hashtag $hashtag)
{
$this->hashtags->removeElement($hashtag);
return $this;
}
/**
* Remove hashtags.
*
* #param Collection|array $hashtags
* #return self
*/
public function removeHashtags($hashtags)
{
foreach($hashtags as $hashtag){
$this->removeHashtag($hashtag);
}
return $this;
}