Comparing data in DB

Question

I have been trying to matching the data from database in a Laravel project but always gave me an alert: Undefined offset: 0 . I have checked different posts in this website but many situations could arise this alert.

The strange point is that if I don't perform matching process, the program works fine but vice versa. Just not sure what's wrong with my code.

This is the controller.

public function addProductAction(Request $request) {
        /*
        check if any input is empty, if validation is fail, error message will display.
        Get required information from addProduct view. And then pass then in the $sql variables.
        DB class will map then to get result.
        */
        $this->validate($request,[
                "product_name" => "required | max:20",
                "description" => "required | max:255",
                "date_of_release" => "required",
                "id" => "required"
            ]);
        $product_name = request("product_name");
        // dd($product_name);
        $description = request("description");
        $manufacturer_id = request("id");
        $date_of_release = request("date_of_release");
        $sql = "SELECT product_name FROM PRODUCT where product_name = ?";    
        $existingProducts = DB::select($sql, array($product_name));
        $existingProduct = $existingProducts[0] -> product_name;
        //dd($existingProduct);
        if ($product_name == $existingProduct) {
            echo "product exists";
        } else {
            $sql = "insert into product (product_name, description, date_of_release) values (?, ?, ?)";
            DB::insert($sql, array($product_name, $description, $date_of_release));
            $id = DB::getPdo()->lastInsertId();
            //dd($id);
            $sql = "insert into PRODUCT_ORIGINAL (product_id, manufacturer_id ) values (?, ?)";
            DB::insert($sql, array($id, $manufacturer_id));
            // dd($newProduct);
            return redirect("product-detail/$id");
        }

        return redirect('/');

    }

This is error message:

at HandleExceptions->handleError(8, 'Undefined offset: 0', '/home/ubuntu/workspace/project_product/app/Http/Controllers/ProductController.php', 216, array('request' => object(Request), 'product_name' => 'Apple iPhone 10', 'description' => 'It is a good computer', 'manufacturer_id' => '1', 'date_of_release' => '2018-09-01', 'sql' => 'SELECT product_name FROM PRODUCT where product_name = ?', 'existingProducts' => array()))
in ProductController.php line 216

$existingProducts variable is empty, so check if request get product_name variable? or there is a record with this product_name in database? — atf.sgf, Sep 02 '18 at 10:06

dWinder · Accepted Answer · 2018-09-02T10:22:49.620

As you can see in your error log:

at HandleExceptions->handleError(8, 'Undefined offset: 0', .... 'existingProducts' => array()))

Your existingProducts array is empty.

Therefor you can access index 0 as you try to do in line:

$existingProduct = $existingProducts[0] -> product_name;

You can solve it with:

$existingProducts = DB::select($sql, array($product_name));
if (!empty(existingProducts ) && $product_name == $existingProducts[0]->product_name) {
        echo "product exists";
} else {

Comparing data in DB

1 Answers1