How to get name and surname by foreign key and add it as new value to current query

This is what laravel relationships is for. You'd create an author relationship in your Artwork model.

Then you could just

$artworks = Artwork::with('author')->orderBy("created_at", "asc")->paginate(12);

which would load the author for each Artwork (which uses the author_id to retrieve behind the scenes)

Then when looping over the artworks, you can access the author properties for each one.

foreach($artworks as $artwork) {
    echo $artwork->someProperty;  // echo a field from $artwork
    echo $artwork->author->name;  // echo the authors name for this $artwork
    echo $artwork->author->surname;
}

https://laravel.com/docs/5.5/eloquent-relationships

There are quite a few videos that illustrate this. Check out the 3rd one in this series: https://laracasts.com/series/digging-in

Thanks a lot! this was what I needed, however I have one more quick question, now I have author relationship in artwork model:

    public function getAuthor()
    {
        return $this->hasOne("App\User", "id", "author_id");
    }

But this selects all columns from author table, would it be possible here to select only name and surname?

Yes. That's called "constraining eager loading". Here are the docs:

https://laravel.com/docs/5.5/eloquent-relationships#constraining-eager-loads

Instead of using a ->where() in the constraint, you'd just use a ->select('name, surname')

But in my case there are two tables users and artworks already joined, this query gets all artworks and with each artwork associates author from users table

    $artworks = Artwork::with("getAuthor")->orderBy("created_at", "asc")->paginate(12);

    public function getAuthor()
    {
        return $this->hasOne("App\User", "id", "author_id");
    }

If I would try to constrain like this

    $artworks = Artwork::with("getAuthor")->select("surname", "name")->orderBy("created_at", "asc")->paginate(12);

It would constrain based on artworks table but I need to constrain only users table.

Yes, check the docs I linked to. Its different than what you wrote.

$artworks = Artwork::with(["getAuthor" => function($query) {
    $query->select("surname", "name");  //this will select `name`, `surname` for author only
}])->orderBy("created_at", "asc")->paginate(12);

Thank you very much! I tried searching for select constraint in your link but it wasn't there, anyways now I see how to add constraints:)

I also found a funny thing, when I used select in this case I had to select id also, for example if I use select() I get everything, if I use select("surname", "name") I get null and if I use select("id", "surname", "name") it behaves as expected, so the final query would look like this:

$artworks = Artwork::with(["getAuthor" => function($query) {
    $query->select("id", "surname", "name");  //this will select `name`, `surname` for author only
}])->orderBy("created_at", "asc")->paginate(12);

Thanks!