symfony Error: Expected =, <, <=, <>, >, >=, !=, got '.'

Question

I have a query that looks for results obtained from a variable in the controller.

$category = $request->request->get('category');

$catContent = $em->getRepository('PublicartelAppBundle:Content')->findByCategory($category);

public function findByCategory($category)
    {
        $em = $this->getEntityManager();

        $dql = 'SELECT c FROM Publicartel\AppBundle\Entity\Content c';

        if (!is_null($category)) {
            $dql .= " WHERE c.categories.name = category";
        }

        $query = $this->getEntityManager()
            ->createQuery($dql)
            ->setHydrationMode(\Doctrine\ORM\Query::HYDRATE_ARRAY);

        if (!is_null($category)) {
            $query->setParameter('category', $category);
        }

        return $query->getResult();
    }

But when I run the action for the query I get this error occurs:

[Syntax Error] line 0, col 71: Error: Expected =, <, <=, <>, >, >=, !=, got '.'

SELECT c FROM Publicartel\AppBundle\Entity\Content c WHERE c.categories.name = category

$categories is an atribute for the entity content.

class Content
{
private $categories;

    public function __construct()
    {
        $this->categories = new \Doctrine\Common\Collections\ArrayCollection();
    }

public function addCategories(\Publicartel\AppBundle\Entity\Category $categories)
    {
        $this->categories[] = $categories;

        return $this;
    }

    public function removeCategories(\Publicartel\AppBundle\Entity\Category $categories)
    {
        $this->categories->removeElement($categories);
    }

    public function setCategories(\Publicartel\AppBundle\Entity\Category $categories = null)
    {
        $this->categories = $categories;

        return $this;
    }
    public function getCategories()
    {
        return $this->categories;
    }
}

The strange thing is that when I get get the variable , the error does not appear.

$category = $request->query->get('category');

Answer 1

You cannot reference subobject this way:

SELECT c FROM Publicartel\AppBundle\Entity\Content c WHERE c.categories.name = :category

You need to JOIN prior to that and use alias of that joined entity. Something like this:

SELECT c, cat FROM Publicartel\AppBundle\Entity\Content c JOIN c.categories cat WHERE cat.name = :category

Now, either use LEFT JOIN or just JOIN and it should work.