how to eager loading nested relationships in Laravel with custom query? - php

Question

I have a comments table, with theses fields: id, body, and parent_id. comments can have subcomments, that's why it is using the parent_id field, I would like to know how I can achieve this nested result:
[
{
"id": 1,
"body": "test",
"parent_id": null,
"comments": [
{
"id": 2,
"body": "test",
"parent_id": 1,
"comments": [
{
"id": 3,
"body": "test",
"parent_id": 2
},
{
"id": 4,
"body": "test",
"parent_id": 2
}
]
},
{
"id": 5,
"body": "test",
"parent_id": 1,
"comments": []
}
]
},
{
"id": 6,
"body": "test",
"parent_id": null,
"comments": []
}
]
Without using eloquent eager loading(with()), just using the query builder, thank you.

Answer 1

Since the possible answer could be too long, I am posting it directly as an answer. You could achieve this by creating a recursive method in your controller like below:
public function commentsLoop($comments, $parent = null)
{
$result = [];
foreach ($comments as $comment) {
if ($comment['parent_id'] === $parent) {
$subComment = commentsLoop($comments, $comment['id']);
if ($subComment) {
$comment['comments'] = $subComment;
}
$result[] = $comment;
}
}
return $result;
}
And then, you can call it from your main method in your controller like below:
public function comments()
{
$comments = DB::table('comments')->all()->toArray();
return $this->commentsLoop($comments);
}
However, if you would use eloquent instead, creating a relationship to self in your model would be the answer.