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 ?

Answer 1

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");

Answer 2

Once you call getResult you have fixed the hydration method to tell Doctrine to return objects. See this page for more discussion of that.

In my opinion, once you have fetched a result set from a relational datastore, it is an odd and rather unpredictable idea that you might fetch the same result multiple times and get different formats of the data.

A better test would be to do the same query multiple times, each time with a different result format.

Answer 3

The solution is use my own query without createQueryBuilder : https://symfony.com/doc/current/doctrine.html#querying-with-dql-or-sql