Doctrine - A new entity was found through the relationship. Where is the mistake?

Question

symfony

Good day.
There are such entities:

There was a task to create a "many-to-many" relationship between categories and brands. The following console solution is written:

public function parseBrands()
    {
        $em = $this->em;
        $categories = $em->getRepository('MainCatalogBundle:Categories')->findAll();
        foreach ($categories as $category) {
            $products = $category->getProducts();
            echo $category->getId();
            foreach ($products as $iteration => $product) {
                $brand = $product->getBrand();

                if (!$brand || $category->getBrands()->contains($brand)) {
                    break;
                }

                $category->getBrands()->add($brand);
                $brand->getCategories()->add($category);

                if ($iteration % 200 === 0) {
                    $em->flush();
                    $em->clear();
                }
            }
            $em->flush();
            $em->clear();
        }
    }

When executing it, the following error pops up:

[Doctrine\ORM\ORMInvalidArgumentException]
A new entity was found through the relationship 'Main\CatalogBundle\Entity\Brand#categories' that was not configured to cascade persist operations for
entity: Main\CatalogBundle\Entity\[email protected] To solve this issue: Either explicitly call EntityManager#persist() on this unkn
own entity or configure cascade persist this association in the mapping for example @ManyToOne(..,cascade={"persist"}). If you cannot find out which entit
y causes the problem implement 'Main\CatalogBundle\Entity\Categories#__toString()' to get a clue.

Adding cascade={"persist"} doesn't really help. What is the problem? A new entity is not created and the EntityManager automatically starts tracking the called entities, doesn't it?

Answer 1

Rewriting the code like this solved the problem.

public function parseBrands()
    {
        $em = $this->em;
        for ($iteration = 2637; $iteration < 3144; $iteration += 1) {
            $category = $em->getRepository('MainCatalogBundle:Categories')->findOneBy(
                array(
                    'id' => $iteration,
                )
            );
            if ($category) {
                echo $category->getId();
                foreach ($category->getProducts() as $product) {
                    $brandId = $product->getBrand()->getId();
                    $brand = $em->getRepository('MainCatalogBundle:Brand')->findOneBy(
                        array(
                            'id' => $brandId,
                        )
                    );

                    if (!$brand || $category->getBrands()->contains($brand)) {
                        break;
                    }

                    $category->getBrands()->add($brand);
                    $brand->getCategories()->add($category);

                    $em->flush();
                }
                $em->clear();
            }
        }
    }