在PHP中使用命名空间循环xml

Question

I'm trying to read the elements of an xml with namespaces in PHP, but I'm having some issues maybe for the presence of several child nodes and for the presence of namespaces. In fact, I have no issues with xml files without namespaces.

I would like to find an elegant way to loop the information inside the nodes, for instance I would like to read all the data (date, store, iditem, price..) inside the elements 'Expense' and possibly inserting them inside an array. Here is the xml:

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
<s:Body>
  <Response xmlns="http://www.w3.org/2001/XMLSchema-instance">
     <Result xmlns:a="http://www.w3.org/2001/XMLSchema-instance" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
        <Success xmlns="http://www.w3.org/2001/XMLSchema-instance">OK</Success>
        <a:Name>John</a:Name>
        <a:Surname>Doe</a:Surname>

        <a:Expenses>

           <a:Expense>
              <a:Date>2019-01-01</a:Date>
              <a:Store>MALL1</a:Store>                 
              <a:Items>
                 <a:Item>
                    <a:IdItem>A1</a:IdItem>
                    <a:Price>5</a:Price>
                 </a:Item>
              </a:Items>
           </a:Expense>

           <a:Expense>
              <a:Date>2019-01-02</a:Date>
              <a:Store>MALL2</a:Store>                 
              <a:Items>
                 <a:Item>
                    <a:IdItem>A2</a:IdItem>
                    <a:Price>1</a:Price>
                 </a:Item>
                 <a:Item>
                    <a:IdItem>A3</a:IdItem>
                    <a:Price>3</a:Price>
                 </a:Item>
              </a:Items>
           </a:Expense>     

        </a:Expenses>
     </Result>
  </Response>

I tried something like this:

$info= new SimpleXMLElement($xml);
$info->registerXPathNamespace('s', 'http://example.com');
$info->registerXPathNamespace('a', 'http://www.w3.org/2001/XMLSchema-instance');

//Example 1:
foreach($info->xpath('//a:Name') as $header)
{
    echo (string) $header; 
}
//Result is: John                   

//Example 2:                    
foreach($info->xpath('//a:Expenses') as $header)
{
    $array = $header->xpath('//a:Expense/a:Store'); 
    print_r($array);
}

//Result is:
/*Array
(
[0] => SimpleXMLElement Object
    (
        [0] => MALL1
    )

[1] => SimpleXMLElement Object
    (
        [0] => MALL2
    )

[2] => SimpleXMLElement Object
    (
        [0] => MALL2
    )

)*/

//Example 3:
$array=$info ->xpath('/*/s:Body'); 
echo (string) $array[0]->Response->Result->Success;
//Result is: OK

But, of course, this is not the best way, because I get only one element at a time and can't make a proper loop. How would you read the various elements of this xml in a more elegant and correct way? Thank you.

Answer 1

This is SOAP, not just XML. The best option would be to use a SOAP library.

However the problem you're facing is that the line foreach($info->xpath('//a:Expenses') as $header) assigns different SimpleXMLElement instances to the $header variables that do not know anything about the registration that you did on the $info variable. You would need to repeat the registration on each SimpleXMLElement .

$info= new SimpleXMLElement($xml);
$info->registerXPathNamespace('s', 'http://example.com');
$info->registerXPathNamespace('a', 'http://www.w3.org/2001/XMLSchema-instance');

foreach($info->xpath('//a:Expenses') as $header)
{
   $header->registerXPathNamespace('a', 'http://www.w3.org/2001/XMLSchema-instance');
   $array = $header->xpath('//a:Expense/a:Store'); 
   print_r($array);
}

Or you start using DOM. In DOM you create an separate object to evaluate Xpath expressions. Because of that you only need to do the registration once. Additionally you can use Xpath expressions that return scalar values.

$document = new DOMDocument();
$document->loadXML($xml);
$xpath = new DOMXpath($document);
$xpath->registerXPathNamespace('s', 'http://example.com');
$xpath->registerXPathNamespace('a', 'http://www.w3.org/2001/XMLSchema-instance');

foreach($xpath->evaluate('//a:Expenses/a:Expense') as $expense)
{
   print_r($xpath->evaluate('string(a:Store)', $expense));
}

Answer 2

A much more simplified version of the code just using SimpleXML. The basic idea is to start with the <Result> (I also use [0] to indicate to use the first element found) element which contains all of the data your after. Then instead of keep on using XPath, fetch all of the child elements in the newly defined a namespace (using children("a", true) ). This will then allow you to access them without any prefix and so use the standard SimpleXML notation -> ...

$info= new SimpleXMLElement($xml);
$info->registerXPathNamespace('a', 'http://www.w3.org/2001/XMLSchema-instance');

$result = $info->xpath("//a:Result")[0]->children("a", true);
//Example 1:
echo $result->Name.PHP_EOL;
//Result is: John

//Example 2:
foreach($result->Expenses->Expense as $header)
{
    echo (string)$header->Store.PHP_EOL;
}

which outputs...

John
MALL1
MALL2