Nested Eager loading relationships in Laravel - laravel

Question

I am creating a forum software using Laravel and I'm trying to access the most recent posts made within a specific topic using latestPost as defined in my model below
public function latestPost() {
return $this->hasOne('App\Post')->with('thread')->with('author')->latest();
}
Here is how the nested relationships are defined in App\Post.php
public function author()
{
return $this->belongsTo('App\User', 'author_id');
}
public function thread()
{
return $this->belongsTo('App\Thread', 'thread_id');
}
public function topic() {
return $this->belongsTo('App\Topic');
}
I have been able to access posts of threads, authors etc no problem, and when I have {{ $topic->latestPost }} in my views, it will list the object including relationships successfully. But as soon as I try to display a specific part such as {{ $topic->latestPost->author->username }} I am getting the following error: Trying to get property of non-object
In this specific view, topics is yet another relationship pulled from Categories like so in the Controller and getting $topics using a #foreach on $categories->topics:
public function index() {
$categories = Category::orderBy('order', 'asc')->get();
return view('welcome', compact('categories'));
}
Here is a dump of $categories: http://dumptext.com/H8Nq16ea

Answer 1

Maybe you want to use nested eager loading.
Change: return $this->hasOne('App\Post')->with('thread')->with('author')->latest();
To this: return $this->hasOne('App\Post')->with('thread.author')->latest();
Also i never heard about latest() and the end of your return statement. Maybe you can try it with orderBy as shown below.
`return $this->hasOne('App\Post')->with('thread.author')->orderBy('id')->first;`
I guess you can use the orderBy('id')->reverse() function if the result is not in the order you want. Let me know if it helped you out.

Answer 2

You should make sure you have author for latest post you want to display. Otherwise if you expect not to have one for each record, you should try:
{{ $topic->latestPost->author ? $topic->latestPost->author->username : 'No author' }}
In addition instead of:
return $this->hasOne('App\Post')->with('thread')->with('author')->latest();
you can use
return $this->hasOne('App\Post')->with('thread','author')->latest();