Laravel Eloquent: with() vs join() JSON Output - json

Question

I have these 2 queries on my Laravel project:
$questions = \App\Answer::rightJoin('questions','answers.id_question','=','questions.id_question')
->leftJoin('users','answers.id_user','=','users.id')->where([
['questions.id_question', '=', $id_question],
['questions.flg_active', '=', true],
])->orderBy('questions.created_at', 'desc')->paginate(5);
and
$questions = \App\Answer::with('question.user')
->orderBy('created_at', 'desc')->paginate(15);
Essencially the first on returns questions not yet answered and the second only returns questions already answered.
I`m trying to use the same blade view for both, but they have different JSON output structure.
The first one returns an one level JSON, while the second returns 3 levels of data.
"data": [{
"id_answer": 42,
"created_at": "2018-11-28 17:52:18",
"updated_at": "2019-05-24 15:09:14",
"id_user": 2,
"id_question": 42,
"str_answer": "onono onooono nonono onn ",
"str_question": "ononon ononon onononn ?",
"url_link": null,
"flg_active": 1,
"id": 1,
"name": "Paul",
"surname": null,
"email": "p#yahoo.com",
"certification": "CFA ...",
"about": "CS, ....."
}
and:
"data": [{
"id_answer": 64,
"created_at": "2019-05-16 15:46:54",
"updated_at": "2019-05-16 15:46:54",
"id_user": 2,
"id_question": 98,
"str_answer": "onono non ooonononn",
"question": {
"id_question": 98,
"created_at": "2019-05-16 15:06:31",
"updated_at": "2019-05-16 15:24:43",
"id_user": 2,
"str_question": "onono onnon ononon?",
"url_link": null,
"flg_active": 1,
"user": {
"id": 2,
"name": "Paul",
"surname": null,
"email": "p#outlook.com",
"created_at": "2018-12-06 05:50:09",
"updated_at": "2019-05-24 11:23:32",
"certification": null,
"about": null
}
}
}
How can I make the first one return in the same 3 levels as the second query does ?
Why this occurs?

Answer 1

The first one is leveraging query builder more and will execute one query which will look something like this:
SELECT * FROM answer
RIGHT JOIN questions ON answers.id_question = questions.id_question
LEFT JOIN users ON answers.id_user = users.id
WHERE questions.id_question = $id_question
AND questions.flg_active = true
ORDER BY questions.created_at desc
OFFSET 0
LIMIT 15
This query returns data from all the tables exactly how sql calculates it. Laravel / Eloquent has no idea how to reliably put this into an eloquent format.
The 2nd one will execute 3 queries which will look something like this:
SELECT * FROM answer
ORDER BY created_at desc
OFFSET 0
LIMIT 15
SELECT * FROM question
WHERE answer_Id IN ($answer_ids) // Will be like (1, 5, 6, 7). All the ids retrieve from the first query
SELECT * FROM user
WHERE queston_id IN ($user_ids)
Eloquent does 3 queries therefore it can create the structure you outlined reliably.
Ultimately it's a trade off, the first option is faster but the response is harder to work with in php which creates less readable code.
I recommend you look at the queries that are executed by each by using the built in query log.
\DB::enableQueryLog();
$builtQuery->get()
dd(\DB::getQueryLog());

Answer 2

This occurs because in your second query you utilize eager loading for your Eloquent relationships. Eloquent model's default toArray() method merges both it's attributes and loaded relationships into one representation.
On the other hand, your first query joins tables, but doesn't load any relationships. So the most straight-forward way you can go about this is to eager load those relationships in your first query just as you do in your second one:
$questions = \App\Answer::with('questions.user')
->rightJoin('questions','answers.id_question','=','questions.id_question')
->leftJoin('users','answers.id_user','=','users.id')->where([
['questions.id_question', '=', $id_question],
['questions.flg_active', '=', true],
])->orderBy('questions.created_at', 'desc')->paginate(5);
Note that this will produce extra SELECT ... WHERE id IN (...) queries for both Question and User models to be eager loaded into their respective relationships.