Having difficulty parsing xml string using simplexml_load_string which returns an empty object

Question

I've been trying to figure out how to parse this xml string.

I get an empty object returned from simplexml_load_string.

Any idea on how to proceed is greatly appreciated.

SimpleXMLElement Object
(
)

This is the XML being received from an ASP.net server. Attempting to parse with PHP.

<?xml version="1.0" encoding="utf-8"?>
<DataSet>
  <xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
    <xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:UseCurrentLocale="true">
      <xs:complexType>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
          <xs:element name="Table">
            <xs:complexType>
              <xs:sequence>
                <xs:element name="MadeBy" minOccurs="0">
                  <xs:simpleType>
                    <xs:restriction base="xs:string">
                      <xs:maxLength value="50" />
                    </xs:restriction>
                  </xs:simpleType>
                </xs:element>
                <xs:element name="Note" minOccurs="0">
                  <xs:simpleType>
                    <xs:restriction base="xs:string">
                      <xs:maxLength value="255" />
                    </xs:restriction>
                  </xs:simpleType>
                </xs:element>
                <xs:element name="DateMade" type="xs:dateTime" minOccurs="0" />
              </xs:sequence>
            </xs:complexType>
          </xs:element>
        </xs:choice>
      </xs:complexType>
    </xs:element>
  </xs:schema>
  <diffgr:diffgram xmlns:msdata="urn:schemas-microsoft-com:xml-msdata" xmlns:diffgr="urn:schemas-microsoft-com:xml-diffgram-v1">
    <NewDataSet>
      <Table diffgr:id="Table1" msdata:rowOrder="0">
        <MadeBy>admin</MadeBy>
        <Note>Test note v2, now with added characters for a longer note!</Note>
        <DateMade>2018-04-02T12:45:18.503-04:00</DateMade>
      </Table>
      <Table diffgr:id="Table2" msdata:rowOrder="1">
        <MadeBy>admin</MadeBy>
        <Note>Test application with a test note</Note>
        <DateMade>2018-04-02T12:44:56.05-04:00</DateMade>
      </Table>
    </NewDataSet>
  </diffgr:diffgram>
</DataSet>

I thought I should get something back other than an empty object.

This was the key that got it working for me: ` $notes_obj = simplexml_load_string($notes);` ` $children = $notes_obj->children('urn:schemas-microsoft-com:xml-diffgram-v1')->children(); ` — Ken Stone, Apr 04 '18 at 02:32

score 1 · Answer 1 · answered Apr 03 '18 at 06:38

As pointed out - print_r() is the wrong thing to check what you have loaded into a SimpleXMLElement. If you ever want to see the content, then use ->asXML() which will print out the XML of any elements.

The following code shows how you can access the data in the XML you have, I use simplexml_load_string, but loaf_file gives the same results...

$xml = simplexml_load_string($data);
print_r($xml);
echo $xml->asXML();
$data = $xml->children("diffgr", true)[0];
foreach ( $data->children("", true)->NewDataSet->Table as $table )  {
    echo "MadeBy=".$table->MadeBy.PHP_EOL;
}

I use the children() method as there are elements in a namespace and this allows you to fetch these easily. children("diffgr", true) fetches the elements in with the namespace prefix diffgr, later I use "" to fetch the elements in the default namespace.

This outputs...

SimpleXMLElement Object
(
)
<?xml version="1.0" encoding="utf-8"?>
<DataSet>
  <xs:schema xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata" id="NewDataSet">
    <xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:UseCurrentLocale="true">
      <xs:complexType>
        <xs:choice minOccurs="0" maxOccurs="unbounded">

         ...

        <DateMade>2018-04-02T12:44:56.05-04:00</DateMade>
      </Table>
    </NewDataSet>
  </diffgr:diffgram>
</DataSet>
MadeBy=admin
MadeBy=admin

score 0 · Answer 2 · answered Apr 02 '18 at 22:00

SimpleXMLElement instances may sometimes appear empty to functions like print_r() or var_dump() even if the XML was properly loaded, since the class is just an interface between PHP and LibXML.

I have tested your XML code and it loads properly, all methods of SimpleXMLElement can be used appropriately.

For example

var_dump($e = simplexml_load_string(...));
var_dump($e->getName());

prints

object(SimpleXMLElement)#1 (0) {
}
string(7) "DataSet"

This thread has some good ideas about how to detect and handle LibXML errors in PHP with the standard interfaces: simplexml error handling php

score 0 · Answer 3 · edited May 24 '19 at 19:13

0

Two things lead to my success. print_r not showing what I thought it was and the children method. I kept overlooking that method in the php.net documentation.

 $notes_obj = simplexml_load_string($notes);

 $children = $notes_obj->children('urn:schemas-microsoft-com:xml-diffgram-v1')->children();

And using

var_export($notes_obj, true)

edited May 24 '19 at 19:13

JDB

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answered Apr 04 '18 at 02:37

Ken Stone

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Having difficulty parsing xml string using simplexml_load_string which returns an empty object

3 Answers3