mysqli_stmt::bind_result(): Number of bind variables doesn't match number of fields in prepared statement (one function works other does not)

Question

This question has been answered before but not in the same format.

I am trying to create an object method to grab a database row. I keep getting the titled error. The odd thing is that if i call the same code of the function directly in the parent class method it works. Here are the two examples.

Example 1: works Function called from seperate PHP page like: $email = trim($_POST['email']); $password = trim($_POST['password']);

$found_user = User::authenticate($email, $password);

Here is the function that is working. (I setup the function as I would have if I were making a reusable function to test if my code was bad)

public static function authenticate($username="", $password="") {

    $db = Database::getInstance();
    $mysqli = $db->getConnection();

    $field = 'email';

    $sql_query  = "SELECT * ";
    $sql_query .= "FROM `".static::$table_name."`";
    $sql_query .= "WHERE {$field}=? ";
    $sql_query .= "LIMIT 1";

    $stmt = $mysqli->stmt_init();

    if (!$stmt->prepare($sql_query)) {
        $error = "Errormessage: " . $mysqli->error;
        return $error;
    }

    if (!$stmt->prepare($sql_query)) {
        $error = "Errormessage: " . $stmt->error;
        return $error;
    } else {
        $stmt->prepare($sql_query);

        $valueType = gettype($username);

        if ($valueType == 'string') {
            $stmt->bind_param('s', $username);  
        } else if ($valueType == 'integer') {
            $stmt->bind_param('i', $username);  
        } else if ($valueType == 'double') {
            $stmt->bind_param('d', $username);  
        } else {
            $stmt->bind_param('b', $username);  
        }

        $stmt->execute();
        $result = $stmt->get_result();

        return $result->fetch_object();
    }       
}

Now, if I call the function in the same method but from an extended class (parent class is User which extends DatabaseOptions). The functions are written as such:

public static function authenticate($username="", $password="") {
    $dbObject = static::get_row('email', $username);

    if (isset($dbObject)) {
        return $dbObject;
    }
}

The function within the DatabaseObject:

public function get_row($field, $value) {
    $db = Database::getInstance();
    $mysqli = $db->getConnection();

    $sql_query  = "SELECT * ";
    $sql_query .= "FROM `".static::$table_name."`";
    $sql_query .= "WHERE {$field}=? ";
    $sql_query .= "LIMIT 1";

    $stmt = $mysqli->stmt_init();

    if (!$stmt->prepare($sql_query)) {
        $error = "Errormessage: " . $stmt->error;
        return $error;
    } else {
        $stmt->prepare($sql_query);

        $valueType = gettype($value);

        if ($valueType == 'string') {
            $stmt->bind_param('s', $value); 
        } else if ($valueType == 'integer') {
            $stmt->bind_param('i', $value); 
        } else if ($valueType == 'double') {
            $stmt->bind_param('d', $value); 
        } else {
            $stmt->bind_param('b', $value); 
        }

        $stmt->execute();
        $result = $stmt->get_result();

        return $result->fetch_object();
    }           
}

Answer 1

public function get_row($field, $value) {
    $db = Database::getInstance();
    $mysqli = $db->getConnection();

    $sql_query  = "SELECT * ";
    $sql_query .= "FROM `".static::$table_name."`";
    $sql_query .= "WHERE {$field}=? ";
    $sql_query .= "LIMIT 1";

    if ($stmt = $mysqli->prepare($sql_query)) {
        $valueType = gettype($value);

        if ($valueType == 'string') {
            $stmt->bind_param('s', $value); 
        } else if ($valueType == 'integer') {
            $stmt->bind_param('i', $value); 
        } else if ($valueType == 'double') {
            $stmt->bind_param('d', $value); 
        } else {
            $stmt->bind_param('b', $value); 
        }

        $stmt->execute();
        $result = $stmt->get_result();
        return $result->fetch_object();
    } else {
        $error = "Errormessage: " . $stmt->error;
        return $error;
    }           
}

The issue with the original code was the fact that I was using bind_result($row), where the row that i was pulling from in the DB has multiple values that would need to be bound. As $result = $stmt->get_result and then returned a fetch_object();.