Groovy Get value of an XML attribute with GPath Slurper

Need to parse an XML document that contains attributes within a header context.

<?xml version="1.0" encoding="UTF-8"?>
<S38:manageRequest xmlns:S38="http://ns.com/S38" xmlns:header="http://ns.com/header/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://ns.com/xsd/ManageItem XSD\ManageItem.xsd">
    <header:standardHeader>
        <header:serviceAddressing>
            <header:to>
                <header:address>http://ns.com/BLAHBLAH</header:address>
                <header:contextItemList>
                    <header:contextItem contextName="Channel" contextId="http://ns.com/contextItem">I Need This</header:contextItem>
                    <header:contextItem contextName="Box" contextId="http://ns.com/contextItem">Blue</header:contextItem>
                </header:contextItemList>
            </header:to>
        </header:serviceAddressing>
    </header:standardHeader>
</S38:manageRequest>

I want to get the attribute "Channel" value of "I Need This" using groovy.util.slurpersupport.GPathResult.

I have found a way that works, but I don't believe it's correct as I am picking the contextItem and luckily the first one is the one I am interested in:

private Map parseServiceAddressing(GPathResult message,Map values){ 
def serviceAddressingList=message."standardHeader"."serviceAddressing"."to"."contextItemList";
    if(serviceAddressingList.isEmpty()){ 
    throw new sourceException("serviceAddressing list is missing",values);
}

def contextItem=serviceAddressingList.'*'.find{
    it.name()=='contextItem'
    };

values.put(tag.CHANNEL, contextItem);

return values;

All attempts to use Channel as the location text fails to retrieve a value. Unfortunately I'm tied to using the GPath as it part of a very large Groovy script I have been asked to modify which does a lot of other stuff.

Can someone please tell me what the correct way of achieving this?

Solution

You should find it using element name and elements attribute is matching the request value as shown below:

def xmlString = """<?xml version="1.0" encoding="UTF-8"?>
<S38:manageRequest xmlns:S38="http://ns.com/S38" xmlns:header="http://ns.com/header/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://ns.com/xsd/ManageItem XSD/ManageItem.xsd">
    <header:standardHeader>
        <header:serviceAddressing>
            <header:to>
                <header:address>http://ns.com/BLAHBLAH</header:address>
                <header:contextItemList>
                    <header:contextItem contextName="Channel" contextId="http://ns.com/contextItem">I Need This</header:contextItem>
                    <header:contextItem contextName="Box" contextId="http://ns.com/contextItem">Blue</header:contextItem>
                </header:contextItemList>
            </header:to>
        </header:serviceAddressing>
    </header:standardHeader>
</S38:manageRequest>"""


def xml = new XmlSlurper().parseText(xmlString)
def cItemChannel = xml.'**'.find {it.name() == 'contextItem' && it.@contextName == 'Channel'}?.text()
println cItemChannel

You can quickly try it online demo