Having Trouble Properly Adding Items to Newsfeed with PHP Script

[Tachyon80]

Hello, all.
I'm having trouble with a PHP script I'm writing to update an RSS newsfeed. It adds a new <item> to the newsfeed but it adds it at the bottom instead of at the top of the list. How can I have it add the new <item> as the first one on the list instead of the last?

Here is the script:

<?php
$xml = simplexml_load_file('test.xml');
$cat1 = 'cat one';
$descrip = 'The description.';
$perma = time() . 'mysite-dot-net' . rand(0, 10000);
$TheLink = 'http://www.example.com/';
$ThePubDate = strftime('%a, %d %b %Y %H:%M:%S %z');
$TheTitle = 'The New Title 3';
$NewOne = $xml->channel->addChild('item');
$NewOne->addChild('category', $cat1);
$NewOne->addChild('description', $descrip);
$NewOne->addChild('guid', $perma);
$NewOne->addChild('link', $TheLink);
$NewOne->addChild('pubDate', $ThePubDate);
$NewOne->addChild('title', $TheTitle);
$xml->asXML('test.xml');
?>

[NogDog]

Here's an (untested) thought:

Use [man]dom_import_simplexml/man to read your simpleXML object into a DOM object. Use [man]DOMNode->insertBefore()[/man] to insert the new node. You could then convert it back to a simpleXML object with [man]simplexml_import_dom/man.

[Tachyon80]

Thanks for the idea, NogDog. I'm trying it but hitting a problem.
Current Code:

<?php
$xml = simplexml_load_file('test.xml');
$cat1 = 'cat one';
$descrip = 'The description.';
$perma = time() . 'mysite-dot-net' . rand(0, 10000);
$TheLink = 'http://www.example.com/';
$ThePubDate = strftime('%a, %d %b %Y %H:%M:%S %z');
$TheTitle = 'The New Title';

$dom_xml = dom_import_simplexml($xml);
$dom = new DOMDocument(1.0);  //line 17
$dom_xml = $dom->importNode($dom_xml, true);  //line 18
$dom_xml = $dom->appendChild($dom_xml);  //line 19
$elements = $dom_xml->get_elements_by_tagname("item");  //line 20
$element = $elements[0];
$NewNode = $element->insert_before($element, $element);
$xml = simplexml_import_dom($dom_xml);

$NewOne = $xml->channel->item[0];
$NewOne->addChild('category', $cat1);
$NewOne->addChild('description', $descrip);
$NewOne->addChild('guid', $perma);
$NewOne->addChild('link', $TheLink);
$NewOne->addChild('pubDate', $ThePubDate);
$NewOne->addChild('title', $TheTitle);
$xml->asXML('test.xml');
?>

My Zend debugger says this:
Fatal error: Call to undefined method DOMElement::get_elements_by_tagname() in testr.php on line 20

Why would it say that's an undefined method?
Also, I'm not sure if lines 17, 18 and 19 are necessary.

I really appreciate your help!

[NogDog]

Shouldn't it be getElementsByTagName()?

[Tachyon80]

Thanks! That solved that problem. Now, when I try

$elements = $dom_xml->getElementsByTagName("item");
$NewNode = $elements->insertBefore($elements, $elements);

or

$elements = $dom_xml->getElementsByTagName("item");
$NewNode = $elements->insert_before($elements, $elements);

I get:
Fatal error: Call to undefined method DOMNodeList::insertBefore()
and:
Fatal error: Call to undefined method DOMNodeList::insert_before()

Is there another form of this method or am I doing something else wrong? Thanks for looking at this!

[Tachyon80]

I still can't make much progress with this.

$elements = $dom_xml->getElementsByTagName("item");
$element = $elements->item(0);
$NewNode = $element->insertBefore($element, $element);

$elements is a DOMNodeList with 10 items. I want to zero in on the first item (index "0") so I try to do that with the 2nd line of code. But the 3rd line of code keeps giving me errors. I want to insert a new <item></item> just before the first item.

I get this:
Fatal error: Uncaught exception 'DOMException' with message 'Hierarchy Request Error'

What does that even mean? Can anyone tell me what I'm doing wrong? I'm guessing I should pass different arguments to the insertBefore command but how do I know which arguments to pass?

[Tachyon80]

My script is running now and doing what I wanted. One question, though: now that I know how to clone an existing node:
$element->cloneNode(true)

How do I create a new one? For example, a new <item></item> (it doesn't have to have anything between the tags).

My working script:

<?php
$xml = simplexml_load_file('test.xml');
$cat1 = 'cat one';
$cat2 = 'cat two';
$descrip = 'The description.';
$perma = time() . 'gearsonline-dot-net' . rand(0, 10000);
$TheLink = 'http://www.example.com/';
putenv('TZ=PST8PDT');
$ThePubDate = strftime('%a, %d %b %Y %H:%M:%S %z');
$TheTitle = 'The New Title';

$dom_xml = dom_import_simplexml($xml);
$elements = $dom_xml->getElementsByTagName("item");
$element = $elements->item(0);
$parent = $dom_xml->getElementsByTagName("channel")->item(0);
$NewNode = $parent->insertBefore($element->cloneNode(true), $element);
$xml = simplexml_import_dom($dom_xml);

$xml->channel->item[0]->category[0] = $cat1;
$xml->channel->item[0]->category[1] = $cat2;
$xml->channel->item[0]->description = $descrip;
$xml->channel->item[0]->guid = $perma;
$xml->channel->item[0]->link = $TheLink;
$xml->channel->item[0]->pubDate = $ThePubDate;
$xml->channel->item[0]->title = $TheTitle;

unset($xml->channel->item[10]);
$xml->asXML('test.xml');
?>