Eloquent (kind of) triple relationship - laravel

Question

I'm having a hard time finding a simple solution, using Eloquent relationships, I have 3 models:
User
Item
Category
Now a User has many Categories, a Category only has one user. A user has many items, an item as many users. And finally an item has many categories and many categories has many items. The tricky part is that although an item can have many categories, it can only has one category from each user, so the reverse would be the user can only associate one category that he owns to the item.
Also the pivot table between item and user(item_user) has two attributes, boolean is_owner and tinyInt permissions
During my application I always have the user ID
I would like to retrieve the expenses that belong to the user, achieving something like this:
[
{
"id": "1",
"value": "0.40",
"description": "Expense 0",
"category": {
"id": "1",
"name": "Health",
"created_at": {
"date": "2015-04-15 01:33:05",
"timezone_type": 3,
"timezone": "UTC"
},
"update_at": {
"date": "2015-04-15 01:33:05",
"timezone_type": 3,
"timezone": "UTC"
}
},
"users": [
{
"id": "1",
"name": "Fabio",
"email": "fabioantuness#gmail.com",
"permissions": {
"expense_id": "1",
"user_id": "1",
"is_owner": "1",
"permissions": "6"
}
}
]
},
{
"id": "2",
"value": "12.40",
"description": "Expense 1",
"category": {
"id": "1",
"name": "Health",
"created_at": {
"date": "2015-04-15 01:33:05",
"timezone_type": 3,
"timezone": "UTC"
},
"update_at": {
"date": "2015-04-15 01:33:05",
"timezone_type": 3,
"timezone": "UTC"
}
},
"users": [
{
"id": "1",
"name": "Fabio",
"email": "fabioantuness#gmail.com",
"permissions": {
"expense_id": "2",
"user_id": "1",
"is_owner": "1",
"permissions": "6"
}
}
]
}
]
Item model:
class Item extends Model {
protected $fillable = ['category_id', 'value', 'description'];
public function users()
{
return $this->belongsToMany('App\User')->withPivot('is_owner', 'permissions');
}
public function categories()
{
return $this->belongsToMany('App\Category');
}
}
User model:
class User extends Model implements AuthenticatableContract, CanResetPasswordContract {
use Authenticatable, CanResetPassword;
protected $table = 'users';
protected $fillable = ['name', 'email', 'password'];
protected $hidden = ['password', 'remember_token'];
public function categories()
{
return $this->hasMany('App\Category');
}
public function items()
{
return $this->belongsToMany('App\Item')->withPivot('is_owner', 'permissions');
}
public function tokens()
{
return $this->hasMany('App\Token');
}
}
Category model:
class Category extends Model {
protected $fillable = ['name'];
public function user(){
return $this->belongsTo('App\User');
}
public function items()
{
return $this->belongsToMany('App\Item');
}
}

Answer 1

Schematizing the question here on stackoverflow helped me get to the solution, here's the query:
User::expenses()->with(
[
'users',
'categories' => function ($query) use ($userId)
{
$query->where('user_id', $userId);
}
]
)->get()->all();
If anyone has a better solution feel free to share it