Error Trying to get Property 'num_rows'

Question

I’m trying to log in, when sending the data to my method, this error appears:

Notice: Trying to get property 'num_rows' of non-object in \controller\user.class.php on line 37
Notice: Trying to get property 'mysqli_num_rows' of non-object in \controller\user.class.php on line 38

//LOGAR 
if (isset($_POST['btn-entrar'])) {
    $username = $_POST['email'];
    $password = $_POST['senha'];
    $password = md5($password);

    if (empty($username) || empty($password)) {
        echo "<div class='alert alert-info mb-2' role='alert'><strong>Atenção!</strong> Email ou Senha estão com os campos vazio, por favor, preencher.</div>";
    }else{
      $user = new User;

      if($user->getUser($username,$password)){
        session_start();
        //$_SESSION['logado'] = true;
        $_SESSION['usuario'] = $username;
        header("Location: ../index.php");
      }else{
        echo "<div class='alert alert-warning mb-2' role='alert'><strong>Atenção!</strong> Esse usuario não existe.
                </div>";
      }
    }
}

//CLASSE
<?php 
//includes
//include_once '../model/connection.php';
class Database{
    private $servername;
        private $user;
        private $password;
        private $dbname;

        public function __construct(){
            $this->servername = 'localhost';
            $this->user = 'root';
            $this->password = '';
            $this->dbname = '';
        }

        public function connect(){
            $conn = new mysqli($this->servername,$this->user,$this->password,$this->dbname);
            return $conn;
        }
}

    class User extends Database{

        public function getUser($username,$senha){
            $obj = new conectar();
            $conexao = $obj->conexao();

            $sql = "SELECT * FROM usuarios WHERE email = '$username' AND senha = '$senha'";




        $result = mysqli_query($conexao,$sql);
        //print_r($result);
        if (mysqli_num_rows($result)== 1) {
            return true;
        }
        return false;
        }
    }

WHERE I AM GOING WRONG?

Answer 1

I think the problem might be this part

$numRows = $result->num_rows;
if ($result->mysqli_num_rows== 1) {
    return true;
}

According to the documentation the msqli::query can return false or MySQLi_Result, or be the first thing you should do and check whether the variable $result is not false, and also according to the documentation MySQLi_Result has no property by the name of mysqli_num_rows is a method with that name, then it must be called as follows mysqli_num_rows().

Applying the correction your code would be +/- like this:

if( $result ){
    // $result e um objeto 'MySQLi_Result'

    if ($result->mysqli_num_rows()== 1) {  // faltava o () `parenteses`
        return true;
    }

    /// nao entrou no if

}
return false;

---

mysqli::query

Value Returned

---

Returns FALSE on Failure. For Successful SELECT, SHOW, DESCRIBE or EXPLAIN darlings mysqli_query() will Return to mysqli_result Object.
For other Successful queries mysqli_query() will Return TRUE.

Which would be translated +/- like this:

Returns FALSE when you fail.
In the success of type queries SELECT, SHOW, DESCRIBE or EXPLAIN returns an object mysqli_result.
In the success of other types queries returns TRUE

The Mysqli class