How do display a variable from a databse with through Relational Models? - php

Question

I have a list of books and a list of authors. I made the Model relations, so that my Book Model says, that books->belongTo('Author') and my Author Model says, that authors->hasMany('Book').
So normally I could access the a variable through this:
$books = Book::all();
And then in the view:
#foreach($books as $book)
<div>{{$book->id}}</div>
<div>{{$book->title}}</div>
<div>{{$book->authors->firstname}}</div>
#endforeach
But this does not work. I get the error message: Trying to get property of non-object
So here are my files:
My Models:
Book.php
class Book extends \Eloquent {
protected $guarded = [];
public function religions()
{
return $this->belongsTo('Religion');
}
public function branches()
{
return $this->belongsTo('Branch');
}
public function authors()
{
return $this->belongsTo('Author');
}
public function quotes()
{
return $this->hasMany('Quote');
}
public function chapters()
{
return $this->hasMany('Chapter');
}
}
Author.php
class Author extends \Eloquent {
protected $guarded = [];
public function books()
{
return $this->hasMany('Book');
}
public function quotes()
{
return $this->hasMany('Quote');
}
public function branches()
{
return $this->belongsTo('Branch');
}
public function religions()
{
return $this->belongsTo('Religion');
}
}
Then come my controller:
ReligionBranchBookController
class ReligionBranchBookController extends \BaseController {
/**
* Display a listing of the resource.
*
* #return Response
*/
public function index($religionId, $branchId)
{
//
// $books = Book::where('religion_id', $religionId)->where('branch_id', $branchId)->get();
$books = Book::all();
$authors = Author::all();
// dd($books->toArray());
return View::make('books.index')
->with('religionId', $religionId)
->with('branchId', $branchId)
->with('books', $books)
->with('authors', $authors);
}
}
My Views:
index.blade.php
#extends('layout.main')
#section('content')
<h1>Books List!!</h1>
<table>
<tr>
<th>ID</th>
<th>Title</th>
<th>Author</th>
</tr>
#foreach($books as $book)
<tr>
<td>{{$book->id}}</td>
<td>{{$book->title}}</td>
<td>{{$book->authors->firstname}}</td>
</tr>
#endforeach
</table>
#stop
I know that it should normally work, I rebuild it with only books and authors, and it works fine there.
So, does anyone have an idea, where I am going wrong?
Thanks,
George

Answer 1

In your Book model change the authors method to author like this:
public function author()
{
return $this->belongsTo('Author');
}
Because, one book belongs to one author according to your relationship and when you call authors the belongsTo->getResults() get called and runs the wrong query so authors get null and you get the error. Things to remember:
For hasOne and belongsTo relationship use singular form of relationship method, i.e, author not authors.
hasOne or belongsTo returns a single model object.
For hasMany and belongsToMany relationship use plural form of relationship method, i.e, authors not author.
hasMany and belongsToMany returns a collection of model objects.