@Cerad gave you a perfectly valid comment. One of the problem of storing arrays is that you don't have any chance of searching.
See PHP/MySQL - Storing array in database, and Storing arrays in the database. As you can see, it is a terrible practice.
The best way is to simply create a Category entity, and to have a OneToMany relation with that category.
Here is an example of an entity Book that has many categories:
1 Create your category entity:
class Category implements CategoryInterface
{
//.....
/**
* Title of the category
*
* @ORM\Column(type="string", length=100)
*/
protected $title;
/**
* Relation with your book entity for example
*
* @ORM\ManyToOne(targetEntity="Book", inversedBy="categories")
* @ORM\JoinColumn(name="book_id", referencedColumnName="id")
*/
private $book;
/**
* Set book
*
* @param BookInterface $book
*/
public function setBook(BookInterface $book)
{
$this->book = $book;
}
/**
* Get book
*
* @return BookInterface
*/
public function getBook()
{
return $this->book;
}
}
2 Your book entity:
use Doctrine\Common\Collections\ArrayCollection;
class Book implements BookInterface
{
/**
* Categories for the books
*
* @ORM\OneToMany(targetEntity="Category", mappedBy="book")
* @var Category[]
*/
protected $categories ;
public function __construct()
{
$this->categories = new ArrayCollection();
}
/**
* Add Categories
*
* @param CategoryInterface $category
*/
public function addCategory(CategoryInterface $category)
{
$category->setBook($this);
$this->categories->add($category);
}
/**
* Remove Category
*
* @param CategoryInterface $category
* @return bool
*/
public function removeCategory(CategoryInterface $category)
{
return $this->categories->removeElement($category);
}
/**
* Get Categories
*
* @return Doctrine\Common\Collections\Collection
*/
public function getCategories()
{
return $this->categories;
}
/**
* Set Categories
*
* @param ArrayCollection $categories
*/
public function setCategories($categories) {
$this->categories->clear();
foreach ($categories as $category) {
$this->addCategory($category);
}
return $this;
}
