Controller For One To Many Relationships - laravel

Question

I'm using Laravel 5.2.
I have 3 tables (writters, publishers and categories) all of the is One to Many Relationships with table named books.
I'm not really sure what the problem is, but everytime i call the the column from 2 of them (nama_penerbit from publishers table and nama_kategori from categories table)from my view blade, it throws me an error Trying to get property of non-object
Here is my models
Book.php
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Book extends Model
{
protected $fillable = [
'judul',
'label',
'isbn',
'tanggal_terbit',
'status',
'id_penulis',
'id_penerbit',
'id_kategori',
];
// Book with Writter
public function writter()
{
return $this->belongsTo('App\Writter', 'id_penulis');
}
// Book with Publisher
public function publisher()
{
return $this->belongsTo('App\Writter', 'id_penerbit');
}
// Book with Category
public function category()
{
return $this->belongsTo('App\Writter', 'id_kategori');
}
}
Publisher.php
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Publisher extends Model
{
protected $fillable = [
'nama_penerbit',
];
// Relation Book with Publisher
public function book() {
return $this->hasMany('App\Book', 'id_penerbit');
}
}
Writter.php
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Writter extends Model
{
protected $fillable = [
'nama_penulis',
];
// Relation Book with Writter
public function book() {
return $this->hasMany('App\Book', 'id_penulis');
}
}
Category.php
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Category extends Model
{
protected $fillable = [
'nama_kategori',
];
// Relation Book with Category
public function book() {
return $this->hasMany('App\Book', 'id_kategori');
}
}
my-view.blade.php
<span>{{ $book->writter->nama_penulis }}</span> // works like a charm
<span>{{ $book->publisher->nama_penerbit }}</span> // throw me an error
<span>{{ $book->category->nama_kategori }}</span> // throw me an error
My question is why nama_penerbit and nama_kategori throw a error while the other one works well
Any sugestion?

Answer 1

You're using Writter model for all three relationships, so fix these relationships by setting correct models:
// Book with Publisher
public function publisher()
{
return $this->belongsTo('App\Publisher', 'id_penerbit');
}
// Book with Category
public function category()
{
return $this->belongsTo('App\Category', 'id_kategori');
}