Laravel Eloquent query with dynamic clauses not working

I am creating a class in Laravel which handles API requests with contain variables. I am then creating the Eloquent model query depending on what variables are passed to this class.

Here is my code:

class FilterVars
{
public static function filterProduct($vars, Product $product) {

    $product->where('id', '=', 1);

    if((array_key_exists('order_by', $vars)) && (array_key_exists('order', $vars))) {
        $product->orderBy($vars['order_by'], $vars['order']);
    }

    return $product->get();
}
}

When I GET this url using postman :http://localhost:8931/api/v1/product?order_by=title&order=desc this returns results fine but none of my where or order_by variables are being taken into account. It returns everything regardless of what I pass in the URl.

Strangely though, when I test this piece of code, the correct results are returned:

$product->where('id', '=', 1)->orderBy($vars['order_by'], $vars['order'])->get();

It works when all the method calls are chained together. Can anyone see why my first code example would not be working?

Thanks

via Chebli Mohamed