Laravel save($request->all()) Error

Hello great people of Stackoverflow!

I have a question, I've been developing laravel application and I encountered this strange error:

QueryException in Connection.php line 770:
SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (`testenv`.`products`, CONSTRAINT `products_tenant_id_foreign` FOREIGN KEY (`tenant_id`) REFERENCES `tenants` (`id`)) (SQL: insert into `products` () values ())

and Here's my store function

public function store(Request $request)
    {
        $product = new Product;

        /*$product->name = $request->name;
        $product->stockQty = $request->stockQty;
        $product->minimumQty = $request->minimumQty;
        $product->description = $request->description;
        $product->notes = $request->notes;
        $product->tenantMargin = $request->tenantMargin;
        $product->length = $request->length;
        $product->height = $request->height;
        $product->weight = $request->weight;
        $product->showLength = $request->showLength;
        $product->showHeight = $request->showHeight;
        $product->showWeight = $request->showWeight;
        $product->size = $request->size;
        $product->colorName = $request->colorName;
        $product->colorHex = $request->colorHex;
        $product->isActive =$request->isActive;
        $product->tenant_id = $request->tenant_id;
        $product->productviewid = $request->productviewid;*/

        $product->save($request->all());

        return "product successfully created";
    }

And the error only occurs if i use

$product->save($request->all()); but if I un-comment the the commented code and use $product->save() instead, it works, no error.

Can anyone help me to find the source of this problem?

via Chebli Mohamed