inserting data into database laravel 5.6 relation belongstomany pivot table - php

Question

i wonder to know how to insert data into pivot table when using a belongsto many relationship i can read the data from database now but i dont know how to store data in database and in my invoice_product table here is the code
model of invoce :
class Invoice extends Model
{
protected $fillable = ['title','description','client_id','product_id'];
public function user() {
return $this->hasOne('App\Client','id','client_id');
}
public function products()
{
return $this->belongsToMany('App\Product', 'invoice_product', 'invoice_id')
->withPivot('product_quantity')
->as('invoice_products_pivot');
}
}
controller of invoice :
public function store(Request $request)
{
//Validate
$request->validate([
'title' => 'required|min:3',
'description' => 'required',
]);
$invoices = Invoice::create([
'title' => $request->title,
'description' => $request->description,
'client_id' => $request->client_id,
'product_id' => $request->product_id,
]);
return redirect('admin/invoices/' . $invoices->id);
}
this stores an invoice into invoice table but i want to get the client_id and product_id or ids cause it must be multiple products and save them into invoice_product table which migration is down here
public function up()
{
Schema::create('invoice_product', function (Blueprint $table) {
$table->increments('id');
$table->integer('client_id');
$table->integer('product_id');
$table->integer('product_quantity');
$table->timestamps();
});
}

Answer 1

to insert data into intermediate or pivot table for many to many relationshiop
you can use attach eloquent method like below
$invoice->products()->attach($product_id)
$product->invoices()->attach($invoice_id)
but your invoice product migration looks a bit odd it should be like this
public function up()
{
Schema::create('invoice_product', function (Blueprint $table) {
$table->increments('id');
$table->integer('invoice_id'); // id of the invoice table
$table->integer('product_id'); // id of the product table
$table->integer('product_quantity'); // client_id should go to the invoice table
$table->timestamps();
});
}