CODEWITHSUNDEEP
phpxmlclientxmpp
Norgul
Norgul

Reputation: 4783

How to control XMPP XML

I am making a XMPP PHP client and currently while in testing phase I have made stanzas (i.e. presence) like this:

    const PRESENCE = <<<PRESENCE
<presence from="{from}" to="{to}" type="{type}" />
PRESENCE;

    const PRIORITY = <<<PRIORITY
<presence from="{from}">
    <priority>{priority}</priority>
</presence>
PRIORITY;

However while developing a library I wanted to do it somewhat programatically as I feel this approach looks like it's hardcoded even though I do parse it like this for example:

$preparedString = str_replace(
    ['{from}', '{priority}'],
    [$from, $priority],
    Xml::PRIORITY
);

So I ended up creating a Presence class which should hold all presence related methods and act as a sort of an XML builder, and it looks like this:

private $instance = null;

public function __construct()
{
    $this->instance = new \DOMDocument();
    $this->instance->formatOutput = true;
}

public function requestPresence(string $from, string $to, string $type = "subscribe")
{
    $presenceNode = $this->instance->createElement('presence');
    $presenceNode->setAttribute("from", $from);
    $presenceNode->setAttribute("to", $to);
    $presenceNode->setAttribute("type", $type);

    return $this->instance->saveXML($presenceNode);
}

public function setPriority(int $priority, string $from = null)
{
    $presenceNode = $this->instance->createElement('presence');
    if ($from)
        $presenceNode->setAttribute("from", $from);

    $priorityNode = $this->instance->createElement('priority');
    $priorityNode->appendChild($this->instance->createTextNode($priority));

    $presenceNode->appendChild($priorityNode);

    return $this->instance->saveXML($presenceNode);
}

But now I have some doubts as I have tripled my code and it was actually more readable before. I would like to keep it simple and effective and without code duplication, but I feel like I'm missing something here. Is there a more slick way to do this?

Upvotes: 0

Views: 45

Answers (1)

Nigel Ren
Nigel Ren

Reputation: 57121

DOMDocument is a more verbose interface for XML, you could use SimpleXML which will reduce the boiler plate code. 

class XML {
    public static function requestPresence(string $from, string $to, string $type = "subscribe")
    {
        $instance = new SimpleXMLElement("<presence />");
        $instance["from"] = $from;
        $instance["to"] = $to;
        $instance["type"] = $type;

        return $instance->asXML();
    }

    public static function setPriority(int $priority, string $from = null)
    {
        $instance = new SimpleXMLElement("<presence />");
        if ($from)  {
            $instance["from"] = $from;
        }
        $instance->priority = $priority;

        return $instance->asXML();
    }
}

This assumes that they are two separate requirements and they are just utility functions rather than having to maintain any state.

If you need to build a document with more options then the following may be more useful...

class XML2 {
    private $instance = null;

    public function __construct()   {
        $this->instance = new SimpleXMLElement("<presence />");
    }

    public function requestPresence(string $from, string $to, string $type = "subscribe")
    {
        $this->instance["from"] = $from;
        $this->instance["to"] = $to;
        $this->instance["type"] = $type;

        return $this;
    }

    public function setPriority(int $priority, string $from = null)
    {
        if ($from)  {
            $this->instance["from"] = $from;
        }
        $this->instance->priority = $priority;

        return $this;
    }

    public function getXML()    {
        return $this->instance->asXML();
    }
}

which called using...

echo  (new XML2())->requestPresence("from", "to", "type")
    ->setPriority(1)
    ->getXML();

creates...

<?xml version="1.0"?>
<presence from="from" to="to" type="type"><priority>1</priority></presence>

Using DOMDocument or SimpleXML solutions will feel more bloated than your original version - but will provide a more robust solution which is more maintainable than relying on string handling.

Upvotes: 1

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