Symfony 4, doctrine, getResult and getArrayResult and getScalarResult return same structure results

Question

From symfony 4, I create a sample repository class. From this class, I created a method for get the list of all email's users. I would like get a array structure like this :

array(
    "email1",
    "email2",
    "email3",
    ...       
)

But with 'getResult' I get a multidimensional array. Then, I tested with getArrayResult and getScalarResult and I obtain each time exactly the same array structure result !

Below, my Service Class :

<?php
class UserRepository extends ServiceEntityRepository
{
    public function __construct(RegistryInterface $registry)
    {
        parent::__construct($registry, User::class);
    }

    public function getAllEmail(){
        $result = $this->createQueryBuilder('u')
            ->select(array('u.email'))
            ->setMaxResults(5)
            ->getQuery();
        return array( // getResult && getArrayResult && getScalarResult return exactly same array structure
            "getResult" => $result->getResult(),
            "getArrayResult" => $result->getArrayResult(), 
            "getScalarResult" => $result->getScalarResult(),
        );
    }
}

And the result when I dump the output of "getAllEmail()" :

Why getResult / getArrayResult / getScalarResult return exactly same array structure ? I do a mistake somewhere ?

Edit : I modified my Repository Class :

public function getAllEmail(){
    $result = $this->createQueryBuilder('u','u.email')
        ->setMaxResults(5)
        ->getQuery();
    return array(
        "getResult" => $result->getResult(),
        "getArrayResult" => $result->getArrayResult(),
        "getScalarResult" => $result->getScalarResult(),
    );
}

And the dump output :

With 'getResult' and 'getArrayResult' I get an multidimensional array and in the first dimension, I get all email (emails are the key). I approach more my goal but its not perfect. I'm looking for the 'light weight' way (sorry for my english -_-), I would like get only email (and not email + another useless users information) because I want execute the simplest query as possible. Is it possible ?

Solution

I might be late but for further notice, I think the right answer is described here.

You can use getScalarResult() then use array_column like that:

$emailArray = array_column($getScalarResult(), "email");

Comments

[spacecodeur]

Thanks for your answer, I modifiy my method. I get differnt results, but I haven't a simple one dimensional array