SimpleXml属性不显示没有子元素的元素

Question

I have the following XML:

<?xml version="1.0"?>
<STATUS_LIST>
    <ORDER_STATUS SORDER_CODE="SO001" ASSOCIATED_REF="001">
        <INVOICES>
            <INVOICE INVOICE_CODE="???">SOMETHING</INVOICE>
        </INVOICES>
    </ORDER_STATUS>
</STATUS_LIST>

When I run the following code:

$statuses = simplexml_load_string($result); //Where $result is my XML

if (!empty($statuses))
{
    foreach ($statuses as $status)
    {
        foreach ($status->INVOICES as $invoice)
        {
            echo (string)$invoice->attributes()->INVOICE_CODE;   
        }
    }
}

I step through this code and I can see the attributes against ORDER_STATUS but I can't see the attributes against INVOICE. I can however see the value SOMETHING against invoice.

Any idea what could cause this?

Update

After some testing, I can get the attributes to show if I add an element into the INVOICE element, so if I use this xml instead it will work:

<?xml version="1.0"?>
<STATUS_LIST>
    <ORDER_STATUS SORDER_CODE="SO001" ASSOCIATED_REF="001">
        <INVOICES>
            <INVOICE INVOICE_CODE="???"><TEST>tester</TEST></INVOICE>
        </INVOICES>
    </ORDER_STATUS>
</STATUS_LIST>

So it has to have an element inside to pick up the attributes!?

Answer 1

Your problem has nothing to do with the element having no content, you simply have your loops defined slightly wrong.

When you write foreach ($status->INVOICES as $invoice), SimpleXML will loop over every child of the $status element which is called INVOICES; in this case there will always be exactly one such element. But what you actually wanted is to loop over all the children of that element - the individual INVOICE nodes.

To do that you can use one of the following:

• foreach ($status->INVOICES->children() as $invoice) (loop over all child nodes of the first, and in this case only, INVOICES element)
• foreach ($status->INVOICES[0]->children() as $invoice) (the same, but being more explicit about selecting the first INVOICES node)
• foreach ($status->INVOICES[0] as $invoice) (actually does the same again: because you've specifically selected one node, and then asked for a loop, SimpleXML assumes you want its children; this is why foreach($statuses as $status) works as the outer loop)
• foreach ($status->INVOICES->INVOICE as $invoice) (loop over only child nodes called INVOICE, which happens to be all of them)

Personally, I would rewrite your sample loop as below:

foreach ($statuses->ORDER_STATUS as $status)
{
    foreach ($status->INVOICES->INVOICE as $invoice)
    {
        echo (string)$invoice['INVOICE_CODE'];   
    }
}

Here's a live demo to prove that that works.