Stumped with Java xPath problem returning null.

[Dale Preston]

I've spent lot of time this weekend trying to solve my first Java xPath issue - though I'm experienced doing xPath in .Net.

I've created this sample and cleaned up XML file (such as no valid IDs and passwords) for testing:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <ns2:DatasourceModule xmlns:ns2="http://www.compositesw.com/ps/deploytool/modules"> <datasource> <genericDataSource> <id>ds1</id> <resourcePath>/shared/TestBU/Physical/Metadata/WSDLDS1</resourcePath> <resourceType>DATA_SOURCE</resourceType> <subType>WSDL_DATA_SOURCE</subType> <dataSourceType>SOAP</dataSourceType> <genericAttribute> <name>SoapURL</name> <type>STRING</type> <value>https://ws.wsdltest.com/services?WSDL</value> </genericAttribute> <genericAttribute> <name>domain</name> <type>STRING</type> <value>testdomain</value> </genericAttribute> <genericAttribute> <name>login</name> <type>STRING</type> <value>wsdllogin1</value> </genericAttribute> <genericAttribute> <name>password</name> <type>PASSWORD_STRING</type> <value>Encrypted:73205312349B8157</value> </genericAttribute> </genericDataSource> </datasource> <datasource> <genericDataSource> <id>ds2</id> <resourcePath>/shared/TESTBU1/Physical/Metadata/SOAP1</resourcePath> <resourceType>DATA_SOURCE</resourceType> <subType>WSDL_DATA_SOURCE</subType> <dataSourceType>SOAP</dataSourceType> <genericAttribute> <name>SoapURL</name> <type>STRING</type> <value>https://www.soapservice.asmx?WSDL</value> </genericAttribute> <genericAttribute> <name>domain</name> <type>STRING</type> <value>testdomain</value> </genericAttribute> <genericAttribute> <name>login</name> <type>STRING</type> <value>soapuser1</value> </genericAttribute> <genericAttribute> <name>password</name> <type>PASSWORD_STRING</type> <value>Encrypted:2CD98E81F123456782C87747BE152763</value> </genericAttribute> </genericDataSource> </datasource> <datasource> <genericDataSource> <id>ds3</id> <resourcePath>/shared/Admin/PROJECTS/COMMON/DATA_SOURCES/DEPLOY_LOG</resourcePath> <resourceType>DATA_SOURCE</resourceType> <subType>FILE_DATA_SOURCE</subType> <dataSourceType>File-Delimited</dataSourceType> <genericAttribute> <name>filters</name> <type>STRING</type> <value>deploy.log</value> </genericAttribute> <genericAttribute> <name>root</name> <type>STRING</type> <value>C:\PDTool\PDTool62B\bin</value> </genericAttribute> </genericDataSource> </datasource> <datasource> <relationalDataSource> <id>ds4</id> <resourcePath>/shared/TESTBU2/Physical/Metadata/DB3</resourcePath> <resourceType>DATA_SOURCE</resourceType> <subType>RELATIONAL_DATA_SOURCE</subType> <dataSourceType>Microsoft SQL Server 2012 jTDS</dataSourceType> <hostname>DBSRV2</hostname> <port>1433</port> <databaseName>DB3</databaseName> <login>loginid3</login> <encryptedPassword>Encrypted:69EBB7BA91123456686EFD048AFE1D04</encryptedPassword> </relationalDataSource> </datasource> <datasource> <genericDataSource> <id>ds21</id> <resourcePath>/shared/BU4/Physical/Metadata/EXCELSOURCE</resourcePath> <resourceType>DATA_SOURCE</resourceType> <subType>NONE</subType> <dataSourceType>Microsoft Excel (non-ODBC)</dataSourceType> <genericAttribute> <name>root</name> <type>STRING</type> <value>\\FILESRV2\DATA\EXCEL DATA SOURCE\EXCEL2</value> </genericAttribute> </genericDataSource> </datasource> </ns2:DatasourceModule>

After my original code kept failing to find the correct results, I created this simple method to try to get the results:

	@Test
	public void testGetFields2() throws XPathExpressionException {
		String xPathQuery = "/ns2:DatasourceModule/datasource[4]/relationalDataSource";
		//Element rootElement = doc.getDocumentElement();
		//NodeList resourcePathNodes = rootElement.getElementsByTagName("resourcePath");
	
		XPath xPath = XPathFactory.newInstance().newXPath();
		XPathExpression xPathExpr = xPath.compile(xPathQuery);
		Node node = (Node) xPathExpr.evaluate(doc, XPathConstants.NODE);
		assertNotNull(node);
	}

Using the xPathQuery in the sample Java code works if I try it against the same XML in various online xPath test sites and it works if I try it against the same XML in Altova XMLSpy. It just doesn't work in Java. The two commented out lines in the Java code were ust used to validate that the document was loaded properly. getElementsById worked with that query to return a NodeList with all of the datasource elements so I know the Document is loaded ok. I just can't seem to get the xPath to work.

Can anyone find what I'm missing and why this doesn't work for me?

Thanks,

Dale

[g tsuji]

.Net and java adapte both a very similar approach to take into account of the namespace(s). In .Net it is XmlNamespaceManager, in java it is NamespaceContext.

[0] If you feel comfortable for this particular xml to bypass the namespace issue, you can write the xpath like this.
//String xPathQuery = "/ns2:DatasourceModule/datasource[4]/relationalDataSource"; String xPathQuery = "//datasource[relationalDataSource]/relationalDataSource";
[1] To treat properly the namespace use in the xpath expression, you set up its NamespaceContext like this. (ns2 is not generic, you can name the prefix whatever you want, systactically correct of course, as long as there is an agrees between the prefix used in the xpath and the NamespaceContext's namespace uri resolution. It is decoupled from what is used in the xml itself.)
XPath xPath = XPathFactory.newInstance().newXPath(); xPath.setNamespaceContext(new NamespaceContext() { //minimalist public String getNamespaceURI(String prefix) { if (prefix.equals("ns2")) { return "http://www.compositesw.com/ps/deploytool/modules"; } else { return null; } } public String getPrefix(String namespaceURI) { return null; } public Iterator<String> getPrefixes(String namespaceURI) { return null; } }); XPathExpression xPathExpr = xPath.compile(xPathQuery);

[Dale Preston]

Thanks, g. I really appreciate the help; removing the namespace from the xPath got me past the problem. I don't need the namespace context for this tool but I appreciate your sample on how to properly handle the namespace. I'm going to tuck that away for future reference.

Dale