Laravel - Eager load a non-relationship method (N+1 issue) - php

Question

With laravel's eager loading, I can do something like
$forums = Forum::with('posts', 'threads')->get();
To get the threads as its posts and forum without doing many queries.
However, I have a method that gets the last post of the forum.
This is my method in Forum.php
public function lastThread()
{
$forums = $this->arrayOfIDs(); // get array of all ids, even subforum's subforums.
return Thread::whereIn('forum_id', $forums)->orderBy('updated_at', 'desc')->first();
}
This is my partial view to get the last thread:
#if ($subforum->lastThread())
<a href="{{ viewThread($subforum->lastThread()) }}">
{{ $subforum->lastThread()->title }}
</a>
<br>
<a href="{{ viewPost($subforum->lastThread()->lastPost) }}"> {{ trans('forum/post.last_post') }}
:</a>
{{ $subforum->lastThread()->lastPost->user->info() }}
<br>
{{ $subforum->lastThread()->lastPost->created_at }}
#endif
As you can see, if I am doing $subforum->lastThread() a lot. I can store it in a variable like $lastThread = $subforum->lastThread() and then do something like $lastThread->created_at to reduce the number of queries but I figured it would be much easier if just include it with the original query to get all forums.
Something like:$forums = Forum::with('posts', 'threads', 'lastThread')->get(); perhaps? I have tried doing a hasOne relation for this method but that does not work because the last thread does not necessarily belong to that specific subforum.
Anyway, how can I best fix this N+1 problem?
Thank you.

Answer 1

you have endless options,
if the Cache class is right for you than I will go with this path, you can also do this:
protectd $lastThread;
public function lastThread()
{
if ($this->lastThread) return $this->lastThread;
return $this->fetchLastThread();
}
public function fetchLastThread() {
$forums = $this->arrayOfIDs(); // get array of all ids, even subforum's subforums.
$this->lastThread = Thread::whereIn('forum_id', $forums)->orderBy('updated_at', 'desc')->first();
return $this->lastThread;
}