Why is var_dump() saying a string is an object?

Question

I'm using an Amazon API to retrieve product information and the response (converted to an object using simplexml_load_string()) looks like this:

SimpleXMLElement Object
(
    [Items] => SimpleXMLElement Object
        (
            [Item] => SimpleXMLElement Object
                (
                    [ASIN] => B00C9WDZIG
                    [ParentASIN] => B00C9WDZIG
                )
        )
)

The output of this:

var_dump($parsed_xml->Items->Item->ASIN);
var_dump($parsed_xml->Items->Item->ParentASIN);

is this:

object(SimpleXMLElement)[3]
  string 'B00C9WDZIG' (length=10)

object(SimpleXMLElement)[4]
  string 'B00C9WDZIG' (length=10)

I'm confused because var_dump() is outputting objects instead of strings. Why is that? Aren't ASIN and ParentASIN string values inside of the third SimpleXMLElement object?

In other words, I expected the output to be:

string 'B00C9WDZIG' (length=10)

string 'B00C9WDZIG' (length=10)

And I'm confused why it wasn't.

Can anyone explain this?

Answer 1

SimpleXML is a chained object. It's deceptive because you can do something like

echo (string)$xml->tag;

And get the value of something like <tag>value</tag>. But tag is also an instance of SimpleXML because you might need to get the attributes or children still. So var_dump is correct.

Let me explain further. Here's some sample XML for you

<xml>
  <mytag>
    <skate>roll</skate>
    <surf>swim</surf>
  </mytag>
</xml>

When we dump this into SimpleXMLElement(SXE), what we get is an instance of SXE. So the top object is our overall wrapper <xml> and we'll say we dumped that into $xml. The next level down is $xml->mytag. This is ALSO an SXE object. So are $xml->mytag->skate and $xml->mytag->surf. If you do

var_dump($xml->mytag->surf);

It will tell you that as well. It needs to be this way because let's say we want to modify the XML. We can just jump straight into

$xml->mytag->addChild('skydive', 'fall');
echo $xml->asXML();

Which outputs

<xml>
  <mytag>
    <skate>roll</skate>
    <surf>swim</surf>
    <skydive>fall</skydive>
  </mytag>
</xml>