Trying to get property of non-object MySQLi result

Asked 2011-09-07T11:09:09.643

Got a bit of PHP code I'm struggling with - had a search around Google etc. and tried everything mentioned, but for some reason I'm having trouble solving it.

The problem is:

I have some code that is querying a database for the presence of a particular user.

The code (it's a method inside a class)

<?php
global $mysqli;
// Query specified database for value
$q = 'SELECT id FROM ' . $database . ' WHERE username = \'' . $username . '\'';
$r = $mysqli->query($q);
var_dump($r);
if ($r->num_rows) {
    // If row found username exists so return false
    return false;
}
...
?>

I've var dumped the result of the query ($r) and got this:

object(mysqli_result)#4 (5) { ["current_field"]=> int(0) ["field_count"]=> int(1) ["lengths"]=> NULL ["num_rows"]=> int(1) ["type"]=> int(0) }

This is correct, there should only be 1 row as above.

I do get this error linking to the line saying if ($r->num_rows) {

Notice: Trying to get property of non-object in FILE on line LINE

but I don't know why since the object is valid (as above) and it should be working fine. From what I can tell it seems to be going through alright, I'm just wondering why there's an error. I'm sure it's something simple but I'd appreciate any help.

php mysqli

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2 Answers

-1

I have been working on to write a custom module in Drupal 7 and got the same error:

Notice: Trying to get property of non-object

My code is something like this:

function example_node_access($node, $op, $account) {
  if ($node->type == 'page' && $op == 'update') {
    drupal_set_message('This poll has been published, you may not make changes to it.','error');
    return NODE_ACCESS_DENY;    
  }
}

Solution: I just added a condition if (is_object($sqlResult)), and everything went fine.

Here is my final code:

function mediaten_node_access($node, $op, $account) {

    if (is_object($node)){

     if ($node->type == 'page' && $op == 'update') {
       drupal_set_message('This poll has been published, you may not make changes.','error');
       return NODE_ACCESS_DENY;    
      }

    }

}

answered 2013-05-13T09:32:06.177

-2

Just thought I would expand on this a bit.

If you perform a MYSQLI SELECT query that returns 0 results, it returns FALSE.

However, if you get this error and you have written your own MYSQLI Query function, then you can also get this error if the query you are running is not a select but an update. An update query will return either TRUE or FALSE. So if you just assume that any non false result will have records returned, then you will trip up when you run an update or anything other than select.

The easiest solution, once you have checked that its not false, is to first check that the result of the query is an object.

    $sqlResult = $connection->query($sql);
    if (!$sqlResult)
    {
     ... 
    }
    else if (is_object($sqlResult))
    {
        $sqlRowCount = $sqlResult->num_rows;
    }
    else
    {
        $sqlRowCount = 0;
    }

answered 2012-05-25T17:13:46.493

Trying to get property of non-object MySQLi result

2 Answers

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