Having Trouble Properly Adding Items to Newsfeed with PHP Script

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:

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 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');
?>

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Just put the elements in reverse order

You could use the DOM XML functions instead of SimpleXML. Then you can use insert_before to insert the new node before the first current item.

You could use the DOM XML functions instead of SimpleXML. Then you can use insert_before to insert the new node before the first current item.

That sounds good.  Would that mean re-writing the code or just adding a line or two?

You could use the DOM XML functions instead of SimpleXML. Then you can use insert_before to insert the new node before the first current item.

That sounds good.  Would that mean re-writing the code or just adding a line or two?

using dom xml is a new code snippet,

anyway, is the feed wrong after you added the node?

The feed is still valid but I want to follow the example of many other sites that cooperate with mine and add new items to the top of the list.

The feed is still valid but I want to follow the example of many other sites that cooperate with mine and add new items to the top of the list.

maybe you can do it different:

parse the existing feed and use the array + the new item(s) and create a new feed

I can't make much progress with this.

Code:

$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?

You can't insert the same element again --- you have to clone it first, or create a new one. Also, you need to insert it into the parent node, otherwise your new node becomes a child of the reference node.

This works:

Code:

$dom_xml=DOMDocument::loadXML("<a><b>hello</b><b/></a>");
echo $dom_xml->saveXML();

$elements = $dom_xml->getElementsByTagName("b");
$parent = $dom_xml->getElementsByTagName("a")->item(0);
$element = $elements->item(0);
$NewNode = $parent->insertBefore($element->cloneNode(true), $element);
echo $dom_xml->saveXML();

anthonyw, I wanted to thank you for your help.  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:

Code:

<?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');
?>

anthonyw, I wanted to thank you for your help.  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).

Code:

$element->cloneNode(false)

will create a new empty element of the same type as the original. Alternatively

Code:

$dom_xml->createElement("item")

  will create an entirely new node of a specified element type.

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