array_rand() does not work on getResult() - php

Question

I am trying to use array_rand() for random entity selection after getResult().
I expect to get an random entity but got int 1(int 2, int 3 etc) instead. Why?
$qb2->select('u')
->from('Application\Entity\User', 'u')
->where('u.usrlId = :sale');
if( !empty($usersIdListForExcluding) ) {
$qb2->andWhere($qb2->expr()->notIn( 'u.usrId', $usersIdListForExcluding ));
}
$qb2->setParameter('sale', 2);
$salesSet = $qb2
->getQuery()->getArrayResult();
var_dump(array_rand($salesSet));
var_dump($salesSet);
First var_dump gives:
int 1
Second one:
array (size=3)
0 =>
object(DoctrineORMModule\Proxy\__CG__\Application\Entity\User)[552]
public '__initializer__' =>
object(Closure)[528]
public '__cloner__' =>
object(Closure)[529]
public '__isInitialized__' => boolean true
private 'usrId' (Application\Entity\User) => int 2
private 'usrName' (Application\Entity\User) => string 'sales_test_1' (length=12)
private 'usrPassword' (Application\Entity\User) => string 'pass' (length=4)
private 'usrEmail' (Application\Entity\User) => string 's_1#gmail.com' (length=13)
...
1 =>
object(Application\Entity\User)[567]
private 'usrId' => int 6
private 'usrName' => string 'sales_test_3' (length=12)
private 'usrPassword' => string 'pass' (length=4)
private 'usrEmail' => string 's_3#gmail.com' (length=13)
private 'usrlId' => int 2
...
2 =>
object(Application\Entity\User)[526]
private 'usrId' => int 7
private 'usrName' => string 'sales_test_4' (length=12)
private 'usrPassword' => string 'pass' (length=4)
private 'usrEmail' => string 's_4#gmail.com' (length=13)
...

Answer 1

array_rand returns a random key (as opposed to a random value). If you want the value then you can access it via the key.
$random_key = array_rand($salesSet);
$random_value = $salesSet[$randomKey];