Hi, i had two modules which are Product and Items Modules Here the relationship between these two module are: Product hasMany items and Items belongsTo product

The table for Product Module are: id, product_name The table for Items Module are: id, products_id, item_name, quantity, price

This is my code for UPDATE

public function update(Request $request)
{
    $product = Product::findOrFail($id);
    $product->product_name = $request->product_name;
    $product->update();
    // Remove all items and add new
    $product->items()->delete();
    // Save each items
    if($request->get('item_name')){
        foreach($request->get('item_name') as $key => $item_name)
        {   
            $items = new Items();
            $items->products_id = $product->id;
            $items->item_name = $item_name;
            $items->quantity = $request->quantity[$key];
            $items->price = $request->price[$key];
            $items->save();
        };
    };
}

The structure for this UPDATE code is whenever there is an update, each items will be deleted and update information will be added as new row.

What i want is the items SHOULD NOT be deleted and add as new. This is because i wants to MAINTAIN THE ITEMS ID. What should i modified to my current code?