Laravel update pivot table - laravel

Question

In laravel I'm trying to update a row from a pivot table. I have this relationships:
Invoice.php
class Invoice extends Model
{
public function items() {
return $this->belongsToMany('App\Item', 'invoice_items', 'invoice_id', 'item_id')->withPivot('quantity');
}
Item.php
class Item extends Model
{
public function invoices() {
return $this->belongsToMany('App\Invoice' ,'invoice_items', 'item_id', 'invoice_id')->orderBy('created_at', 'desc')->withPivot('quantity');
}
}
InvoiceItem.php
class InvoiceItem extends Pivot
{
protected $fillable = [
'quantity',
];
public function __construct(Model $parent, array $attributes,
$table, $exists = false)
{
parent::__construct($parent, $attributes, $table, $exists);
}
}
and in InvoicesController.php I have method update:
public function update(Request $request, $id)
{
$invoice = Invoice::findOrFail($id);
$invoice->update([
'number' => $request->number,
'status' => $request->status,
'place_issue' => $request->place_issue,
'date_issue' => $request->date_issue,
'date_payment' => $request->date_payment,
'description' => $request->description,
'company_id' => $request->company_id,
'user_id' => $request->user_id,
]);
Invoice::find($id)->items()->updateExistingPivot($request->quantity, ['quantity' => $request->quantity]);
return redirect('listInvoice');
}
Every time I try to update the field "quantity" is the old value. What am I doing wrong?

Answer 1

As each invoice may have multiple items, you can loop through and update the quantity of the item by its key.
I'm not sure what $request->quantity is returning. You may need some additional logic to ensure you are updating the correct item.
$items = $invoice->items->pluck('name', 'id')->toArray();
foreach ($items as $key => $item) {
$invoice->items()->updateExistingPivot($key, ['quantity' => $request->quantity]);
}