Attatch multiple values from checkox, with many-to-many relation in Laravel - laravel

Question

I am trying to attatch book and warehouses upon creating a new book in my laravel project.
At the moment i have a checkbox for each warehouse, in my view:
#foreach($warehouses as $warehouse)
<input type="checkbox" name="checked[]" value="{{ $warehouse->id }}">
{{ $warehouse->address }}
<br/>
#endforeach
And i have the many to many relations in my book and warehouse models:
Book:
class Book extends Model
{
use HasFactory;
protected $table = 'books';
protected $fillable = [
'ISBN', 'publisher_id', 'author_id', 'year', 'title', 'price',
];
public function warehouses()
{
return $this->belongsToMany(Warehouse::class);
}
Warehouse:
class Warehouse extends Model
{
use HasFactory;
protected $table = 'warehouses';
protected $fillable = [
'name', 'address', 'phone', 'url',
];
public function books()
{
return $this->belongsToMany(Book::class);
}
When submitting the foreach in the form on my book.create view, i try to attach each checked warehouses in the same process as creating the new book:
My Create method:
public function create()
{
$authors = Author::all();
$selectedAuthor = Book::first()->author_id;
$publishers = Publisher::all();
$selectedPublisher = Book::first()->publisher_id;
$warehouses = Warehouse::all();
$selectedWarehouse = Book::first()->warehouse_id;
return view('books.create', compact(['authors', 'publishers', 'warehouses'],
['selectedAuthor', 'selectedPublisher', 'selectedWarehouse']
));
}
And my store method to store the created data:
public function store(Request $request)
{
$request->validate([
'ISBN' => 'required',
'author_id' => 'required',
'publisher_id' => 'required',
'year' => 'required',
'title' => 'required',
'price' => 'required',
]);
try {
Book::create($request->all());
$book = Book::first(); // Book::first(); saves to the first found book (id 1), needs to be fixed to the requested book.
foreach ($request->checked as $value){
$book->warehouses()->attach([$value]);
}
return redirect()->route('books.index')
->with('success','Book created successfully.');
} catch (\Illuminate\Database\QueryException $e) {
var_dump($e->errorInfo);
}
}
The problem is my
$book = Book::first();
saves to the first found book (id 1, even though i might be creating book id 43), needs to be fixed to the requested book that is currently being created.

Answer 1

I have updated my store method by assigning
Book::create($request->all());
To my $book variable which solved the problem, my store method now looks like this:
public function store(Request $request)
{
$request->validate([
'ISBN' => 'required',
'author_id' => 'required',
'publisher_id' => 'required',
'year' => 'required',
'title' => 'required',
'price' => 'required',
]);
try {
$book = Book::create($request->all());
foreach ($request->checked as $value){
$book->warehouses()->attach([$value]);
}
return redirect()->route('books.index')
->with('success','Book created successfully.');
} catch (\Illuminate\Database\QueryException $e) {
var_dump($e->errorInfo);
}
}
And saves the many-to-many relational data upon storing.
Thank you very much for the help Dennis :-)