Laravel 5.3 - multiple db queries when loading relations - laravel

Question

I have posts table (id, user_id, title) and Post model with this content
class Post extends Model
{
public function user()
{
return $this->belongsTo('App\User');
}
}
I want to get some post by id and also the user's information, so I use this query
$post = new Post();
$res = $post->where('id', 1)->select('id', 'title', 'user_id')->with([
'user' => function ($query) {
$query->select('id', 'name', 'email');
}
])->first();
It returns the data as expected, and i can access the post's info like $res->title, or the user's info like $res->user->email, but the problem is it makes 2 queries to the database
I would expect to have one query only
SELECT
`posts`.`id`,
`posts`.`title`,
`posts`.`user_id`,
`users`.`id`,
`users`.`email`,
`users`.`name`
FROM
`posts`
LEFT JOIN `users`
ON `posts`.`user_id` = `users`.`id`
WHERE `posts`.`id` = '1'
LIMIT 1
Please note, this is not the same as N+1 problem
https://laravel.com/docs/5.3/eloquent-relationships#eager-loading
I know I can manually do left join,
$res = $post->where('posts.id', 1)
->select('posts.id', 'posts.title', 'posts.user_id', 'users.email', 'users.name')
->leftJoin('users', 'posts.user_id', '=', 'users.id')
->first();
and it will have the one query as I need, but the problem is in the result all data from related table is in the same array (and besides, what is the point of defining/using relationships if i have to manually make a left join every time)
So, my question is how to get the post data with related tables with one query and result organized according to relations: I am curious what is the best practice in laravel and how experienced Laravel developers are doing this ?
Thanks

Answer 1

Eloquent never uses JOINs to retrieve relationship data, but instead uses seperate queries and links the data together in PHP objects. Therefore, you will always have one extra query for each relationship. Also, Eloquent mostly loads all columns (using *).
To link them together, you have to stop using the query builder and instead use Eloquent directly:
$post = Post::find(1)->load('user');
If you insist on using JOINs, you will have to continue using the query builder.

Answer 2

That is eager loading.
You are using
->with([
'user' => function ($query) {
$query->select('id', 'name', 'email');
}
])
In eager loading, what happens is first run above query and get all the users matching the query.
Then the result is applied to the outer query which is
$post->where('id', 1)->select('id', 'title', 'user_id')->with([
'user' => function ($query) {
$query->select('id', 'name', 'email');
}
])->first();