How can I check whether an array parameter is empty? - php

Question

I want to select users from a database with Doctrine and Symfony. Depending on whether I have a supplied list of user IDs I want to only select users with these IDs. If the list is empty, then all users should be selected.
Here is the code I have created so far:
class UserRepository extends EntityRepository {
public function selectUsers (array $userIds) {
$dql = "
SELECT
u
FROM
MyBundle:User
WHERE
u.id IN (:users)"; // OR (:users) does not contain any values
$query = $this
->getEntityManager()
->createQuery($dql)
->setParameter("users", $userIds);
return $query->getResult();
}
}
How can I check whether the array is empty? So far, I have tried IS EMPTY, = (), = [], SIZE(:users) = 0, COUNT(:users) = 0 but all of them give me errors. What is the correct syntax here?

Answer 1

You can dynamically build DQL query
public function selectUsers(array $userIds)
{
$dql = "SELECT u FROM MyBundle:User";
$params = array();
if ($users) {
$dql .= " WHERE u.id IN (:users)";
$params["users"] = $userIds;
}
return $this->getEntityManager()->createQuery($dql)->execute($params);
}
You are building two different queries - select all, select specific users. I think you cannot build such SQL query. Maybe DQL has some shortcut how you can do it, but I would prefer SQL-ish syntax.

Answer 2

The only solution I have come up with so far is to calculate the count in PHP and pass it in as an additional parameter.
class UserRepository extends EntityRepository {
public function selectUsers (array $userIds) {
$dql = "
SELECT
u
FROM
MyBundle:User
WHERE
u.id IN (:users) OR :userCount = 0";
$query = $this
->getEntityManager()
->createQuery($dql)
->setParameter("users", $userIds)
->setParameter("userCount", count($userIds));
return $query->getResult();
}
}
However, I have a hard time believing that this is impossible to do directly in DQL.