Catchable fatal error: Object of class PDOStatement could not be converted to string in line 114

Question

I\'m trying to add some data to my database, but I\'m getting the error Catchable fatal error: Object of class PDOStatement could not be converted to string in /var/www/mand

Answer 1

foreach($_SESSION["cart"] as $id => $value)
{

        $query = $db->query('SELECT * FROM Producten WHERE ProductID ="'.$id.'" ');
        $query->execute();

        while($row = $query->fetch(PDO::FETCH_ASSOC))
        {

            $price = $row['Prijs'];
            $ProductID = $row['ProductID'];

        }

$array = array( $max, $ProductID, $value, $price );

$sql->prepare
    ("
    INSERT INTO Bestellingsdetail (Bestelnummer, ProductID, Aantal, Prijs)
    VALUES (?, ?, ?, ?)
    ")

$sql->execute($array);

}

Answer 2

In the comments, you show the following:

$query = $db->query('SELECT MAX( Bestelnummer ) FROM Bestellingsdetail');
$query->execute();
$max = $query;
$max++;

This is not how you get the result from a query. You are setting $max to a PDOStatement object. You need to fetch() the result in order to use it.

// I've added "AS maxval" to make it easier to get the row
$query = $db->query('SELECT MAX(Bestelnummer) AS maxval FROM Bestellingsdetail');
$max_row = $query->fetch(PDO::FETCH_ASSOC);

$max = $max_row['maxval'];
$max++;

Docs: http://www.php.net/pdo.query

P.S. $query->execute(); is only needed for prepared statements. query() will execute the query immediately.

Answer 3

Try:

foreach($_SESSION["cart"] as $id => $value){

        $query = $db->query('SELECT * FROM `Producten` WHERE ProductID ="'.$id.'" ');
        $query->execute();

        while($row = $query->fetch(PDO::FETCH_ASSOC)){
            $price = $row['Prijs'];
            $ProductID = $row['ProductID'];
            }
        $sql="INSERT INTO `Bestellingsdetail`( `Bestelnummer`, `ProductID`, `Aantal`, `Prij`s)
        VALUES ($max,$ProductID,$value,$price)";
        $smtp = $db->prepare($sql);
        $count = $smtp->execute();

However, try and use the prepared statements as you are defeating the reason of using PDO and could be at risk of injection:

foreach($_SESSION["cart"] as $id => $value){

        $query = $db->query('SELECT * FROM `Producten` WHERE ProductID ="'.$id.'" ');
        $query->execute();

        while($row = $query->fetch(PDO::FETCH_ASSOC)){
            $price = $row['Prijs'];
            $ProductID = $row['ProductID'];
            }
        $sql="INSERT INTO `Bestellingsdetail`( `Bestelnummer`, `ProductID`, `Aantal`, `Prijs`)
        VALUES (:max,:ProductID,:value,:price)";
        $stmt = $db->prepare($sql);
        $stmt->bindParam(':max', $max);
        $stmt->bindParam(':ProductID', $ProductID);
        $stmt->bindParam(':value', $value);
        $stmt->bindParam(':price', $price);
        $count = $smtp->execute();