Appending an XML File Using PHP - php

Question

I have a PHP file which contains a HTML form. When the user enters data into the form, it carries out error checking and if everything is in order the data entered is written to an XML file in a specific order. This part works perfectly. My problem is when the user fills in this form again, I need the new data to append to the XML file (not overwrite it). Currently, it simply over writes the data, could someone help me out on how I would do this? I tried watching tutorials but I am very new to XML and found them confusing. My XML file is as follows;
<?php
function createFile($xml_file)
{
$FileMessageID = $_POST['messageid'];
$FileCreation = $_POST['filedatetime'];
$FileTransactions = $_POST['filetransactions'];
$FileControlSum = $_POST['filecontrolsum'];
$CID = $_POST['CID'];
// create new dom document
$xml = new DOMDocument();
// these lines would create a nicely indented XML file
$xml->preserveWhiteSpace = false;
$xml->formatOutput = true;
// create a root element, and add it to DOM
addRoot($xml);
// add more elements to xml file
$CustomerDDInfo = $xml->createElement("CstmrDrctDbtInitn");
// add this element to the root
$xml->documentElement->appendChild($CustomerDDInfo);
// create elements
$GroupHeader = $xml->createElement("GrpHdr");
$InitiatingParty = $xml->createElement("InitgPty");
$IdentificationHeading = $xml->createElement("Id");
$PrivateIdentification = $xml->createElement("PrvtId");
$Other = $xml->createElement("Othr");
// append these elements to friend
$CustomerDDInfo->appendChild($GroupHeader);
$GroupHeader->appendChild($xml->createElement('MsgID', $_POST['messageid']));
$GroupHeader->appendChild($xml->createElement('CreDtTm', $_POST['filedatetime']));
$GroupHeader->appendChild($xml->createElement('NbOfTxs', $_POST['filetransactions']));
$GroupHeader->appendChild($xml->createElement('CtrlSum', $_POST['filecontrolsum']));
$GroupHeader->appendChild($InitiatingParty);
$InitiatingParty->appendChild($IdentificationHeading);
$IdentificationHeading->appendChild($PrivateIdentification);
$PrivateIdentification->appendChild($Other);
$Other->appendChild($xml->createElement('Id', $_POST['CID']));
$CustomerDDInfo->appendChild($PaymentInformation);
// save dom document to an xml file
$xml->save($xml_file);
}
function addRoot(&$xml)
{
$xml->appendChild($xml->createElement("entry"));
}
// call xml function
createFile('SEPA.xml');
//Redirect to Thank You Page
header ('Location: thankyou.php');
?>

Answer 1

load the existing XML document (if there is one)
add a child at the correct level with the information you would like to append
An XML is not like a text file, where you just put other data at the bottom of it. In XML you have to put the extra information inside a node somewhere inside the existing XML.
<exampleXML>
<item>
<name></name>
<number></number>
<date></date>
</item>
</exampleXML>
When another item to the XML you should load the XML, take the 'exampleXML' node and append a child to it.
Result:
<exampleXML>
<item>
<name></name>
<number></number>
<date></date>
</item>
<item>
<name></name>
<number></number>
<date></date>
</item>
</exampleXML>
I don't often work with XML DOM in PHP so I can't really provide you any code.
Look at http://www.php.net/manual/en/class.domdocument.php for the correct functions.