Avoid hardcoding XML in PHP for an API request - php

Question

I'm sending the following XML to an api using cURL:
$xml = "<request type='auth' timestamp='$timestamp'>
<merchantid>$merchantid</merchantid>
<account>$account</account>
<orderid>$orderid</orderid>
<amount currency='$currency'>$amount</amount>
<card>
<number>$cardnumber</number>
<expdate>$expdate</expdate>
<type>$cardtype</type>
<chname>$cardname</chname>
</card>
<sha1hash>$sha1hash</sha1hash>
</request>";
What is the best way to avoid hard coding this XML? I was thinking of using XMLWriter but seems strange as it won't be changing.
Should I use a template? Or generate it using XMLWriter / Simple XML?

Answer 1

As I mentioned in the comments, there's not necessarily a right answer to this but I recently had to write a project around an XML API Feed as well. I decided to go with XMLWriter and it's still very easy to interchange into others easily by using their respected .loadXML() functions.
class SomeApi extends XMLwriter {
public function __construct() {
$this->openMemory();
$this->setIndent( true );
$this->setIndentString ( " " );
$this->startDocument( '1.0', 'UTF-8', 'no' );
$this->startElement( 'root' );
}
public function addNode( $Name, $Contents ) {
$this->startElement( $Name );
$this->writeCData( $Contents );
$this->endElement();
}
public function output() {
$this->endElement();
$this->endDocument();
}
//Returns a String of Xml.
public function render() {
return $this->outputMemory();
}
}
$newRequest = new SomeApi();
$newRequest->addNode( 'some', 'Some Lots of Text' );
$Xml = $newRequest->render();
I think it's a nice clean way writing an XML Feed in PHP, furthermore as you can add internal functions such as:
$this->addHeader();
private function addHeader() {
$this->addNode( 'login', 'xxxxx' );
$this->addNode( 'password', 'xxxxx' );
}
Which then appends nodes that you'll use over & over again. Then if you suddenly need to use a DOMDocument object for example (As I needed too for XSL).
$Dom = new DOMDocument();
$Dom->loadXML( $Xml );

Answer 2

Should I use a template?
You actually already did use a template here.
Or generate it using XMLWriter / Simple XML?
XMLWriter and also SimpleXMLElement are components that allow you to create XML easily. For your specific case I'd use SimpleXML for a start:
$xml = new SimpleXMLElement('<request type="auth"/>');
$xml['timestamp'] = $timestamp;
$xml->merchantid = $merchantid;
$xml->account = $account;
$xml->orderid = $orderid;
$xml->addChild('amount', $amount)['currency'] = $currency;
$card = $xml->addChild('card');
$card->number = $cardnumber;
$card->expdate = $expdate;
$card->type = $cardtype;
$card->chname = $cardname;
$xml->sha1hash = $sha1hash;
See that the XML is not hardcoded any longer, only the names used are. The SimpleXML library takes care to create the XML (demo, here the output is beautified for better readability):
<?xml version="1.0"?>
<request type="auth" timestamp="">
<merchantid></merchantid>
<account></account>
<orderid></orderid>
<amount currency=""/>
<card>
<number></number>
<expdate></expdate>
<type></type>
<chname></chname>
</card>
<sha1hash></sha1hash>
</request>
Thanks to the library, the output is always valid XML and you don't need to care about the details here. You can further simplify it by wrapping it more, but I don't think this is of much use with your very little XML you have here.