Symfony Querybuilder left join merge arrays - php

Question

I am currently facing a problem using the query builder and a left join. What I want to achieve is select all columns from the Article-Entity and, using a left join with two conditions, "append" a field to that array. In the snippet you'll see the working query without a join and the query with the left join and their results.
I know you can use "getScalarResult", but that produces the result shown in the snippet as well - it prefixes all columns from table "Article". What I would want is that result without the "a_" prefixes.
I know you can list the table fields in the select statement, but I do not want that query to be static but rather have it dynamic for when the table structure might change.
// default query
return $this->createQueryBuilder('a')
->andWhere('a.publishedAt IS NOT NULL')
->andWhere('a.publishedAt <= CURRENT_TIMESTAMP()')
->andWhere('a.status = 2')
->orderBy('a.publishedAt', 'DESC')
->getQuery()
->getResult();
// default result
array:5 [
0 => Article {#723
-id: 18
-title: "Title!"
-slug: "slug"
-content: "content"
-image: "img.jpg"
-author: BackendUser {#817 ▶}
-status: 2
-publishedAt: DateTime #1536546264 {#720 ▶}
-ratingPositive: 1
-ratingNegative: 0
-articleRatings: PersistentCollection {#816 ▶}
#createdAt: DateTime #1539163998 {#715 ▶}
#updatedAt: DateTime #1539180102 {#709 ▶}
}
...
]
// Left-Join-Query:
return $this->createQueryBuilder('a')
->andWhere('a.publishedAt IS NOT NULL')
->andWhere('a.publishedAt <= CURRENT_TIMESTAMP()')
->andWhere('a.status = 2')
->leftJoin('App\Entity\Article\ArticleRating', 'ar', 'WITH', 'ar.article = a.id AND ar.user = ' . $userId)
->addSelect('ar.rating as userRating')
->orderBy('a.publishedAt', 'DESC')
->getQuery()
->getResult();
// Left Join Result
array:5 [
0 => array:2 [
0 => Article {#722 ▼
-id: 18
-title: "Title"
-slug: "Slug"
-content: "Content"
-image: "image.jpg"
-author: BackendUser {#817 ▶}
-status: 2
-publishedAt: DateTime #1536546264 {#689 ▶}
-ratingPositive: 1
-ratingNegative: 0
-articleRatings: PersistentCollection {#816 ▶}
#createdAt: DateTime #1539163998 {#737 ▶}
#updatedAt: DateTime #1539180102 {#732 ▶}
}
"userRating" => true
]
...
]
// getScalarResult - result
array:5 [▼
0 => array:12 [▼
"a_id" => 18
"a_title" => "Title"
"a_slug" => "slug"
"a_content" => "content"
"a_image" => "image.jpg"
"a_status" => 2
"a_publishedAt" => DateTime #1536546264 {#689 ▶}
"a_ratingPositive" => 1
"a_ratingNegative" => 0
"a_createdAt" => DateTime #1539163998 {#737 ▶}
"a_updatedAt" => DateTime #1539180102 {#732 ▶}
"userRating" => "1"
]
...
]
My desired outcome would look like something like this:
array:5 [
0 => Article {#722 ▼
-id: 18
-title: "Title"
-slug: "Slug"
-content: "Content"
-image: "image.jpg"
-author: BackendUser {#817 ▶}
-status: 2
-publishedAt: DateTime #1536546264 {#689 ▶}
-ratingPositive: 1
-ratingNegative: 0
-articleRatings: PersistentCollection {#816 ▶}
#createdAt: DateTime #1539163998 {#737 ▶}
#updatedAt: DateTime #1539180102 {#732 ▶}
-userRating- => true
}
...
]