How to check if many-to-many relation already exists in create and update - laravel

Question

Every time I create a new book or update it with the same author, a new instance of the same author creates in DB
This is my codes here
Here is the BooksController
<?php
namespace App\Http\Controllers;
use App\Models\Author;
use App\Models\Book;
use Illuminate\Http\Request;
class BooksController extends Controller
{
/**
* Display a listing of the resource.
*
* #return \Illuminate\Http\Response
*/
public function index()
{
$books = Book::orderBy('created_at', 'desc')->with('authors')->paginate(5);
return view('books.index', [
'books' => $books
]);
}
/**
* Show the form for creating a new resource.
*
* #return \Illuminate\Http\Response
*/
public function create()
{
return view('books.create');
}
/**
* Store a newly created resource in storage.
*
* #param \Illuminate\Http\Request $request
* #return \Illuminate\Http\Response
*/
public function store(Request $request)
{
$request->validate([
'author_name' => 'required',
'title' => 'required',
'release_year' => 'required|numeric',
'status' => 'required',
]);
I think I need to check here
// check if author already exists..
$authors = Author::all();
foreach($authors as $a){
if($a->name == $request->input('author_name')){
$author = $a;
}else{
}
}
Here if I have Glukhovski in the database and create a new book with the same author, another Glukhovski is added in the database, so I think there must be a way to check and if the author already exists, assign it to the book through the pivot table?
$author = Author::create([
'name' => $request->input('author_name')
]);
$book = Book::create([
'title' => $request->input('title'),
'release_year' => $request->input('release_year'),
'status' => $request->input('status')
]);
$book->authors()->attach($author->id);
return redirect('/books');
}
/**
* Display the specified resource.
*
* #param int $id
* #return \Illuminate\Http\Response
*/
public function show($id)
{
$book = Book::find($id);
return view('books.show')->with('book', $book);
}
/**
* Show the form for editing the specified resource.
*
* #param int $id
* #return \Illuminate\Http\Response
*/
public function edit($id)
{
$book = Book::find($id);
return view('books.edit')->with('book', $book);
}
/**
* Update the specified resource in storage.
*
* #param \Illuminate\Http\Request $request
* #param int $id
* #return \Illuminate\Http\Response
*/
public function update(Request $request, $id)
{
$request->validate([
'author_name' => 'required',
'title' => 'required',
'release_year' => 'required',
'status' => 'required',
]);
... and here as well
// check if author already exists.....
//
$author = Author::create([
'name' => $request->input('author_name')
]);
$book = Book::find($id);
$book -> update([
'title' => $request->input('title'),
'release_year' => $request->input('release_year'),
'status' => $request->input('status')
]);
$book->authors()->sync($author->id);
return redirect('/books');
}
/**
* Remove the specified resource from storage.
*
* #param int $id
* #return \Illuminate\Http\Response
*/
public function destroy($id)
{
Book::find($id)->delete();
return redirect('books');
}
}
Pivot table:
<?php
use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;
class CreateAuthorBookTable extends Migration
{
/**
* Run the migrations.
*
* #return void
*/
public function up()
{
Schema::create('author_book', function (Blueprint $table) {
$table->id();
$table->foreignId('author_id');
$table->foreignId('book_id');
});
}
/**
* Reverse the migrations.
*
* #return void
*/
public function down()
{
Schema::dropIfExists('author_book');
}
}

Answer 1

you can check first for author in this way before you create the author, if author doesn't exist, it will create a new one
$author = Author::where('name',$request->input('author_name'))->first();
if(!$author){
$author = Author::create([
'name' => $request->input('author_name')
]);
}