problem changing XML value

Dustie

Hi all

Ok, I've pretty much cracked reading in and outputting XML data. Now, I'm trying to change the odd node value here and there but am not having a lot of luck.

Here's the code:

$xmlDoc = new DOMDocument();
$xmlDoc->load('furnace.xml');
$xmlGigs = $xmlDoc->getElementsByTagName("gig");

$calendar = array(
	"title" => array(),
);

$i = 0;
foreach ($xmlGigs as $Gig)
	{
	$calendar['title'][$i] = $Gig->getElementsByTagName("title");
	if ($calendar['title'][$i]->length == 0)
		{
		// the value is null so change it to "unknown"
		$calendar['title'][$i]->item(0)->nodeValue = "unknown";
		}
	echo $calendar['title'][$i]->item(0)->nodeValue . "<br/>";
	++$i;
	}

Basically, I just want to read in all the instances of <title></title> into the $calendar array. Sometimes, these don't exist on the XML sheet though (deliberately) so, in cases like this, I want to replace it with "unknown".

Can't get it to work though - I just get these errors:

Strict Standards: Creating default object from empty value
Notice: Trying to get property of non-object

Can anyone help?

bradgrafelman

If the length is 0, then there is no item(0), so you're trying to change the nodeValue of a node that doesn't exist. Instead, you're going to have to create that node first.

Dustie

Hmmm, ok, I seem to be stumbling at the first hurdle:

if ($calendar['title'][$i]->length == 0)
		{
		// the value is null so change it to "unknown"
		[B]$newNode = $calendar['title'][$i]->createElement("test");[/B]
		}

I'm trying the above as a first step but it just errors out with:

Call to undefined method DOMNodeList::createElement()

🙁

bradgrafelman

Take a look at the manual page for DOMDocument::createElement() (link: [man]domdocument.createelement[/man]). As the function name suggests, the 'createElement' method is called on the DOMDocument object itself. You then create the element as desired and append it as a child of some other node in the document using DOMNode::appendChild() (link: [man]domnode.appendchild[/man]).

Also note that your code comment:

// the value is null so change it to "unknown"

isn't really correct. It's not that the "value is null", it's that there is no such node. In other words, you're talking about the value of something that doesn't exist... obviously you can't just "change it to 'unknown'" because that doesn't change the fact that the node doesn't exist (meaning there is no value to change in the first place).

Dustie

ok so, if I'm not actually working on the DOM itself but an array that's been created using just some parts of it, do I need to approach this differently?

bradgrafelman

Dustie wrote:
if I'm not actually working on the DOM itself

But you are, aren't you? If not, how do you explain these lines:

$xmlDoc = new DOMDocument();
$xmlDoc->load('furnace.xml');