"Call to a member function query() on a non-object" when it works elsewhere?

PHP
1

Hi

I have spent days trying to figure this out, and am my wits end. I have an include file which essentially get all the entries from a database table which contains two columns - cat_id and cat_name.

I connect to this include file several times from different parts of the program using $_SERVER[‘DOCUMENT_ROOT’].

Here is the include file:


//get all categories
$result = $link->query('SELECT cat_id, cat_name FROM category');
if (!$result) {
    $error = 'Error fetching category details.';
    include $_SERVER['DOCUMENT_ROOT'] . '/includes/error.html.php';
    exit();
}
while ($row = mysqli_fetch_array($result)) {
    $categories[] = array('cat_id' => $row['cat_id'], 'cat_name' => $row['cat_name']);
}

The code snippet below works:


ini_set('memory_limit', '-1');
include_once $_SERVER['DOCUMENT_ROOT'] . '/includes/magicquotes.inc.php';
include_once $_SERVER['DOCUMENT_ROOT'] . '/../code4/common.php';
include_once $_SERVER['DOCUMENT_ROOT'] . '/../code4/db.inc.php';
checkUser();

//Show form to add new subcategory
if (isset($_GET['add'])) {
    $pagetitle = 'New Sub-Category';
    $sideNav = '<p><a href="../logout.php">Always Logout when finished</a></p>
    <p><a href="../index.php">Return to CMS Home</a></p>
    <p><a href="">Edit existing Sub-Category</a></p>';
    $catHead = 'Select category to associate with subcategory type:';
    $action = 'addform';
    $subcat_id = '';
    $cat_id = '';
    $subcat_code = '';
    $subcat_name = '';
    $title_txt = '';
    $meta_description = '';
    $meta_keywords = '';
    $top_txt = '';
    $bot_txt = '';
    $add_info = '';
    $add_info_link = '';
    $specs = '';
    $foot_txt = '';
    $table_type = '';
    $button = 'Add Sub-Category';
    include $_SERVER['DOCUMENT_ROOT'] . '/includes/getAllCategories.php';
    include 'form.html.php';
    exit();
}

However, the snippet following is the one I am having trouble with. When I connect to this part of the script, I get the error message: “[28-Aug-2012 20:35:13] PHP Fatal error: Call to a member function query() on a non-object in /Users/cliffgs/Sites/goldenfields.dev/includes/getAllCategories.php on line 4”.

But when I run the script shown above, which connects to the very same include file, it works. I simply do not know what is going on. I have tried explicitly outputting this php errors, but they just tell me that it a string, not an object. But that doesn’t really help me, because I cannot understand why it should be different considering I am always using $link as the database object, and it works in one (and other) situations, but not in this one. Can someone help me with what I am obviously missing.


ini_set('memory_limit', '-1');
include_once $_SERVER['DOCUMENT_ROOT'] . '/includes/magicquotes.inc.php';
require_once $_SERVER['DOCUMENT_ROOT'] . '/../code4/common.php';
include_once $_SERVER['DOCUMENT_ROOT'] . '/../code4/db.inc.php';
checkUser();

//Show form to add new product
if (isset($_GET['add'])) {
    $pagetitle = 'New Product';
    $sideNav = '<p><a href="../logout.php">Always Logout when finished</a></p>
    <p><a href="../index.php">Return to CMS Home</a></p>
    <p><a href="">Edit existing Product</a></p>';
    $catHead = 'Select category to associate with subcategory type:';
    $action = 'addform';
    $id = '';
    $cat_id = '';
    $subcat_id = '';
    $pID = '';
    $orderedBy = '';
    $description = '';
    $short_desc = '';
    $coverage = '';
    $weight = '';
    $price = '';
    $priceINTL = '';
    $info = '';
    $manu = '';
    $link = '';
    $button = 'Add new Product';
    include $_SERVER['DOCUMENT_ROOT'] . '/includes/getAllCategories.php';
//    include_once $_SERVER['DOCUMENT_ROOT'] . '/includes/getProductSubcat.php';
    include 'form.html.php';
    exit();
}

I should also add, that I have changed the offending script so that instead of including the the getAllCategories file, I just pasted in that same code. It would therefore appear that the problem is with that script, but I cannot see where.

Many thanks

2

$link = ‘’;

You have this line in the second snippet.

3

Ye Gods I cannot believe that!!! Thanks Guido, you have saved my life, even though I still feel stupid! Of course “link” is a column in the product table, but I never gave that a thought.

Thanks very much for spotting that for me. Maybe, sometime in the next ten years I may have seen it, but I am not sure.

Thank you.

4

The clue was in the error message.

“Call to a member function query() on a non-object”

So you should have looked for ->query(‘some stuff in here’).

When you found that, you’d have seen it was being called on a $link variable which is supposed to be an object, but it is not?

So what is it?

So you’d do this:

var_dump($link);

Which would have likely said something like:


var link string 0 "";

So then you’d go looking for where $link was defined.

I’m not trying to rub it in, just explaining how you would interpret this particular error message so that you’ve got more chance of fixing it quicker.

5

Thanks Cups, I know you are not rubbing it in, I take all the help I can. Once the cause of the error was pointed out to me by Guido2004 I felt so stupid. I had been looking in every direction but the correct one. Still, that is yet another mistake I won’t make again.

Thank you for your comment.