Cannot serialize SimpleXMLElement to Laravel job - php

Question

So, after doing some studying I have successfully managed to parse some XML that I'm getting via Guzzle via simplexml_load_string. The issue is then when I then subsequently try to dispatch a job for each of the children using the following code I get a "Serialization of 'SimpleXMLElement' is not allowed" error.
$parent = $this->getParent($keywords);
foreach ($parent->children() as $child) {
dispatch(new ProcessChild($event, true), $this->otherVar);
}
So to try and fix this I can use the following trick to convert the XML into an array;
json_decode(json_encode($child))
however, while this does mean I can send the data to the new job, it does mean that, as far as I can work out, I have no way to access the #attributes. An alternative would be something along the lines of the following;
// ParentJob
$parent = $this->getParent($keywords);
foreach ($parent->children() as $child) {
dispatch(new ProcessChild($child->asXML, true), $this->otherVar);
}
// ChildJob
public function __construct($xml, $otherVar)
{
$this->xml = simplexml_load_string($xml);
$this->otherVar = $otherVar;
}
however it still throws a serialization error on the dispatch for some reason that I cannot work out, since it sould only be sending raw XML and not an object.
So my main question is what would be the correct way to pass and child SimpleXMLObject to a job in Laravel 5.3 ?
(short of something like looping through all the nodes/attributes and building my own collection from them)

Answer 1

Converting the XML into JSON that way means loosing data. I suggest keeping the XML if possible.
SimpleXMLElement::asXML() is a method. Do not forget the brackets.
$parent = $this->getParent($keywords);
foreach ($parent->children() as $child) {
dispatch(new ProcessChild($child->asXML(), true), $this->otherVar);
}
Calling it as a property means that SimpleXML tries to interpret it as a child element node. This means it will be an (empty) SimpleXMLElement.
Here is a small example showing the behavior:
$node = new SimpleXMLElement('<foo/>');
var_dump($node->asXml);
var_dump($node->asXml->getName());
var_dump($node->asXml());
Output:
object(SimpleXMLElement)#2 (0) {
}
string(0) ""
string(29) "<?xml version="1.0"?>
<foo/>
"

Answer 2

The SimpleXmlElement can be converted to array as follows:
$xml = <<<'XML'
<root>
<x a="a1">1</x>
<y b="b2">2</y>
<z>3</z>
</root>
XML;
$xe = simplexml_load_string($xml);
$a = $xe->xpath('*');
$a = array_map(function ($e) {
$item = (array) $e;
$item['nodeName'] = $e->getName();
return $item;
}, $a);
// Now `$a` is an array (serializable object)
echo json_encode($a, JSON_PRETTY_PRINT);
Output
[
{
"#attributes": {
"a": "a1"
},
"0": "1",
"nodeName": "x"
},
{
"#attributes": {
"b": "b2"
},
"0": "2",
"nodeName": "y"
},
{
"0": "3",
"nodeName": "z"
}
]
Note, you can get the string value of a SimpleXmlElement by casting it to string:
$item['value'] = (string) $e;
Since xpath method supports relative XPath expressions, the asterisk should work even with namespaced XMLs. Consider using the DOM extension, as it is much more flexible than SimpleXML. In particular, its DOMXPath class allows to register namespaces and use the registered identifiers in the XPath expressions:
$xpath->registerNamespace('myprefix', 'http://example.com/ns');
$xpath->query('/root/myprefix:*');

Answer 3

As it turns out the entire reason it was not working was due to me using simplexml_load_string() on the child jobs constructor, which was turning it into a simpleXMLElement before the job was actually serialized and pushed onto the queue. the correct way to do it was to parse the XML string on the handle method, which is done after the job has been pulled from the queue for actual processing.
Now this works I can simply dispatch the child job with $child->asXML, and parse it when the job is actually being processed, meaning I can still use all the nifty simpleXML features such as attributes().
Example ParentJob:
foreach ($parent->children() as $child) {
dispatch(new ProcessChild($event, true), $this->otherVar);
}
Example ChildJob:
protected $xml;
protected $otherVar;
public function __construct($xml, $otherVar)
{
$this->xml = $xml;
$this->otherVar = $otherVar;
}
public function handle()
{
$child = simplexml_load_string($this->xml);
$attributes = $child->attributes();
}