New Mysqli Object is Null

Question

I'm trying to create a connection to a MySQL database using Mysqli in PHP. When I execute the following code on a stand alone page:

<?php
ini_set('display_errors', 'On');
error_reporting(E_ALL);

$link = new mysqli('localhost', 'myuser', 'mypass', 'dbname');
var_dump($link);

All I get outputted is an empty Mysqli object where all the properties are null. No error or anything gets displayed.

I also don't see any entries in the Apache or MySQL logs. I'm kind of at a lost on this one.

Answer 1

I had this problem too and was going crazy trying to debug it. It turns out that sometimes for whatever reason the mysqli object does not get populated, but directly accessing it's properties still executes the native code behind it. So even though a var_dump of the entire mysqli object shows null properties, they are there if you access them individually. If errorno turns out to be false, you may have executed a valid query with an empty resultset that you weren't expecting. Hope this helps.

$mysqli = mysqli_connect('localhost', 'root', '', 'test', 3306);

var_dump($mysqli);

var_dump($mysqli->client_info);
var_dump($mysqli->client_version);
var_dump($mysqli->info);

and the output:

object(mysqli)[1]
  public 'affected_rows' => null
  public 'client_info' => null
  public 'client_version' => null
  public 'connect_errno' => null
  public 'connect_error' => null
  public 'errno' => null
  public 'error' => null
  public 'field_count' => null
  public 'host_info' => null
  public 'info' => null


public 'insert_id' => null
  public 'server_info' => null
  public 'server_version' => null
  public 'stat' => null
  public 'sqlstate' => null
  public 'protocol_version' => null
  public 'thread_id' => null
  public 'warning_count' => null

string 'mysqlnd 5.0.8-dev - 20102224 - $Revision: 321634 $' (length=50)
int 50008
null
int 0
string 'localhost via TCP/IP' (length=20)
string '5.5.20-log' (length=10)
int 50520

Answer 2

I know this is a bit old, but for anyone who still has this as a recurring issue, the comment from user3158900 to danperron's post has the solution. I'm re-posting here to make it more visible. Also, some example code is included:

global $mysqli; //assuming you've already created your $mysqli object
$mysqli->query("INSERT INTO users SET username='jim' and password='somehash'");
var_dump( $mysqli ); //prints the full object but all the values are null 

//the following code prints the full object with appropriate values such as
//insert_id, affected_rows, etc
//view http://pastebin.com/Mgd2CZsM for an example of this output
echo "<pre>" . print_r( $mysqli, true ). "</pre>";