return random data form database in random order and with limit

Question

I'm new with symfony and I'm trying to view data from one of my tables with random order and a limit of 4. I tried doing it in the repository but RAND() is not working so I'm trying in the controller.

The error is the following one:

"Warning: array_rand() expects parameter 1 to be array, object given"

And I don't understand why, when in the $response I set the data into an array.

This is my actual code:

/**
* @Route("/ws/random/superviviente", name="ws_random_survi")
*/
    public function randomSurvi(Request $request): Response
    {
        $data = $request->request->all();
        $entityManager = $this->getDoctrine()->getManager();

        $randomPerks = $entityManager->getRepository(Perks::class)
            ->getRandomPerks();
        
        $response = new JsonResponse();
        $response -> setStatusCode(200);
        $response -> setData(array('random perk' => $randomPerks));

        $resultRandom = array_rand($response);

        return $resultRandom;
        
    }

The data inside `$response` is an array, but `$response` self is an object of type `JsonResponse`. — simon.ro, Mar 30 '21 at 11:14
What have you tried to debug the problem? Running `array_rand` on something that obviously is **not** an array sounds strange — Nico Haase, Mar 30 '21 at 13:27

Dylan KAS · Answer 1 · 2021-03-30T13:02:49.093

You are trying to use array_rand on a doctrine array collection.

You could either convert it as array and back to a doctrine array :

use Doctrine\Common\Collections\ArrayCollection;
public function randomSurvi(Request $request): Response
    {
        $data = $request->request->all();
        $entityManager = $this->getDoctrine()->getManager();

        $randomPerks = $entityManager->getRepository(Perks::class)
            ->getRandomPerks();
        
        $resultRandom = new ArrayCollection(array_rand($randomPerks->toArray()));

        return new JsonResponse($resultRandom);
        
    }

Otherwise it would work with shuffle :

 $randomPerks = $entityManager->getRepository(Perks::class)->getRandomPerks();
 $randomPerks = shuffle($randomPerks);

Or get random perks directly through your method in your repository.

See example from @Krzysztof Trzos:

  public function getRandomProducts($amount = 7)
    {
        return $this->getRandomProductsNativeQuery($amount)->getResult();
    }


/**
 * @param int $amount
 * @return ORM\NativeQuery
 */
public function getRandomProductsNativeQuery($amount = 7)
{
    # set entity name
    $table = $this->getClassMetadata()
        ->getTableName();

    # create rsm object
    $rsm = new ORM\Query\ResultSetMapping();
    $rsm->addEntityResult($this->getEntityName(), 'p');
    $rsm->addFieldResult('p', 'id', 'id');

    # make query
    return $this->getEntityManager()->createNativeQuery("
        SELECT p.id FROM {$table} p ORDER BY RAND() LIMIT 0, {$amount}
    ", $rsm);
}

with the first option this error appears: Attempted to call an undefined method named "toArray" of class "Symfony\Component\HttpFoundation\JsonResponse". — bafecas538, Mar 30 '21 at 12:13
My bad, used wrong variable, fixed it, other part on my answer should work tho — Dylan KAS, Mar 30 '21 at 13:01

score 0 · Answer 2 · answered Mar 30 '21 at 12:02

You could write your own query to achieve this, so create a new method inside the repository like so:

public function getRandomPerks(int $limit): array
{
    $queryBuilder = $this->createQueryBuilder('p');

    return $queryBuilder
        ->setMaxResults($limit)
        ->orderBy('RAND()')
        ->getQuery()
        ->getResult();
}

Then in your controller all you would to do is call the method and pass a limit:

$randomPerks = $entityManager->getRepository(Perks::class)
    ->getRandomPerks(4);

inside the createQueryBuilder my custom select? – bafecas538 Mar 30 '21 at 12:11 — bafecas538, Mar 30 '21 at 12:11

return random data form database in random order and with limit

2 Answers2