XPath expression for xml with namespace prefix
Given the following xml:
<ns0:MCCI_IN000002UV01 xmlns:ns0="urn:hl7-org:v3">
<ns0:id root="2.16.840.1.113883.3.277.100.1" extension="68423f2b-397a-4de4-8b8d-ea1f6c174954" />
<ns0:creationTime>201410171106-0700</ns0:creationTime>
<ns0:versionCode code="Ballot2009May" />
<ns0:interactionId root="2.16.840.1.113883.1.6" extension="MCCI_IN000002UV01" />
<ns0:processingCode code="P" />
<ns0:processingModeCode code="T" />
<ns0:receiver nullFlavor="NA">
<ns0:device nullFlavor="NA" classCode="DEV" determinerCode="INSTANCE">
<ns0:id nullFlavor="NA" />
</ns0:device>
</ns0:receiver>
<ns0:sender nullFlavor="NA">
<ns0:device nullFlavor="NA" classCode="DEV" determinerCode="INSTANCE">
<ns0:id nullFlavor="NA" />
</ns0:device>
</ns0:sender>
<ns0:acknowledgement typeCode="CA">
<ns0:targetMessage>
<ns0:id root="2.16.840.1.113883.3.277.100.1" extension="adb32b05-bf62-4417-8c62-d37a65380c4f" />
</ns0:targetMessage>
<ns0:acknowledgementDetail typeCode="I" />
</ns0:acknowledgement>
</ns0:MCCI_IN000002UV01>
I was unable to query the hl7: MCCI_IN000002UV01 / hl7: versionCode / @ attribute using the BizTalks XPathMutatorStream class unless I changed the xml and removed the namespace prefix. So, for example, the xml will now look like this:
<MCCI_IN000002UV01 xmlns="urn:hl7-org:v3">
<id root="2.16.840.1.113883.3.277.100.1" extension="68423f2b-397a-4de4-8b8d-ea1f6c174954" />
...
</MCCI_IN000002UV01>
Unfortunately, I cannot change the xml, so I have to deal with the ns0 prefix.
Basically, I create an XMLReader object by passing a stream to it:
XmlReader xr = XmlReader.Create(strMyStream);
Then I create my XPathCollection using XPathExpression:
XPathCollection xc = new XPathCollection();
xc.NamespaceManager = new XmlNamespaceManager(xr.NameTable);
xc.NamespaceManager.AddNamespace("hl7", "urn:hl7-org:v3");
xc.Add(new XPathExpression("hl7:MCCI_IN000002UV01/hl7:versionCode/@code"));
I am passing my XPathCollection and XmlReader instances to the BizTalk XPathMutatorStream object:
XPathMutatorStream str = new XPathMutatorStream(xr, xc, ...);
This all works fine if there is no namespace prefix in the xml, but once that happens I never get any matches. Is there something I need to do in the namespace manager or valid xpath statements to get the match?
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If you want to use Linq2Xml:
var xDoc = XDocument.Load(filename);
1 - Using XPath
XmlNamespaceManager mgr = new XmlNamespaceManager(xDoc.CreateNavigator().NameTable);
mgr.AddNamespace("hl7", "urn:hl7-org:v3");
var version = xDoc.XPathSelectElement("hl7:MCCI_IN000002UV01/hl7:versionCode", mgr);
var code = version.Attribute("code").Value;
2 - Using Linq
XNamespace h17 = "urn:hl7-org:v3";
var code2 = xDoc.Descendants(h17 + "versionCode").First().Attribute("code").Value;
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