How to fetch data with PDO into class with enum property?

Question

Since the enum feature was released in PHP8.1, I was wondering how can I fetch data from my database with PDO into an object with an ENUM property.

I have the following enum:

enum UserType{
  case Master: 1;
  case Admin: 2;
  case Manager: 3;
}

And I have the following class:

class User{
  private int $id;
  private string $name;
  private UserType $userType;
}

Every time I try to execute the code below I get the error Cannot assign int to property User::$userType of type UserType

Database::getInstance()->fetchObject(sql: "SELECT id, name, userType FROM user WHERE id = 1", class_name: User::class);

I want to know if there is a way to make the code above works or what is the best way to implement the new enum feature in my code.

My fetchObject code:

public function fetchObject($sql, array $args = array(), string $class_name = "stdClass"): mixed
{
    $sql = self::$instance->prepare($sql);
    if(empty($args)){
        $sql->execute();
    } else{
        $sql->execute($args);
    }
    $object = $sql->fetchObject($class_name);
    $sql->closeCursor();
    return $object;
}

score 3 · Accepted Answer · answered Nov 17 '21 at 14:13

You can't do it with fetchObject(). The reason is that you can't assign int to a property of type UserType. You can use a magic method __set(), but you would have to not declare the property (this is highly not recommended).

You can use __set with lazy property initialization and PDO::FETCH_CLASS|PDO::FETCH_PROPS_LATE. If that's confusing for you, this is because it is confusing.

enum UserType:int {
    case Master = 1;
    case Admin = 2;
    case Manager = 3;
}

class User
{
    private int $id;
    private string $name;
    private UserType $userType;

    public function __construct()
    {
        // unset it for lazy initialization (PDO will call __set method instead)
        unset($this->userType);
    }

    public function __set($key, $value)
    {
        if ($key === 'userType') {
            $this->userType = UserType::from($value);
        }
    }
}

// Tell PDO to call constructor first,
// then try to assign the property if it exists or call magic method __set()
$stmt->setFetchMode(PDO::FETCH_CLASS | PDO::FETCH_PROPS_LATE, User::class);
$user = $stmt->fetch();

It might be easier to just stick to doing this in the constructor. You could then fetch the row as an associative array and unpack it into the constructor.

class User
{
    private UserType $userType;

    public function __construct(private int $id, private string $name, int $userType)
    {
        $this->userType = UserType::from($userType);
    }
}

Then your fetchObject() would look like:

public function fetchObject($sql, array $args = [], string $class_name = "stdClass"): ?object
{
    $stmt = self::$instance->prepare($sql);
    $stmt->execute($args ?: null);
    $row = $stmt->fetch(PDO::FETCH_ASSOC);
    return $row ? new $class_name(...$row) : null;
}

You need to unpack the row because PDO doesn't have the capability to pass values to the constructor.

How to fetch data with PDO into class with enum property?

1 Answers1