Develop Reference

Retrieve multiple attributes with XPath

I have an XML file that's similar to this (each element has more attributes):
<DocBuild>
<XMLDependency name="Name1" product="Product ABC" area="JKL" />
<XMLDependency name="Name2" product="Product DEF" area="MNO" />
<XMLDependency name="Name3" product="Product GHI" area="PQR" />
</DocBuild>
I want to retrieve each 'name' attribute and the 'area' for that element so I can build a list that looks like this (I've inserted a dash between 'name' and 'area' for clarity):
Name1-JKL
Name2-MNO
Name3-PQR
public static Element getConfig(...) throws XPathExpressionException{
String path = MessageFormat.format("//DocBuild//XMLDependency[#name='Name1']//#area ")
}

Use some rules like regular expressions! In this case you must use "|" which is used as OR clause.
// Create XPathFactory object
XPathFactory xpathFactory = XPathFactory.newInstance();
// Create XPath object
XPath xpath = xpathFactory.newXPath();
String name = null;
try {
XPathExpression expr =
xpath.compile("/DocBuild/XMLDependency[#name='Name1']//#name|/DocBuild/XMLDependency[#name='Name1']//#area");
NodeList nl = (NodeList)expr.evaluate(doc,XPathConstants.NODESET);
String nameAttr = "";
for (int index = nl.getLength()-1; index >= 0; index--) {
Node node = nl.item(index);
nameAttr += node.getTextContent();
nameAttr += "-";
}
nameAttr = nameAttr.substring(0,nameAttr.lastIndexOf("-"));
System.out.println(nameAttr);
} catch (XPathExpressionException e) {
e.printStackTrace();
}
See XPath Syntax

This XPath 2.0 expression,
/DocBuild/XMLDependency/concat(#name,'-',#area)
evaluates directly to
Name1-JKL
Name2-MNO
Name3-PQR
for your sample XML, as requested.

Getting a node from an XML document

I use the worldweatheronline API. The service gives xml in the following form:
<hourly>
<tempC>-3</tempC>
<weatherDesc>rain</weatherDesc>
<precipMM>0.0</precipMM>
</hourly>
<hourly>
<tempC>5</tempC>
<weatherDesc>no</weatherDesc>
<precipMM>0.1</precipMM>
</hourly>
Can I somehow get all the nodes <hourly> in which <tempC>> 0 and <weatherDesc> = rain?
How to exclude from the response the nodes that are not interesting to me <hourly>?

This is quite feasible using XPath.
You can filter a document based on element values, attribute values and other criteria.
Here is a working example that gets the elements according to the first point in the question:
try (InputStream is = Files.newInputStream(Paths.get("C:/temp/test.xml"))) {
DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document xmlDocument = builder.parse(is);
XPath xPath = XPathFactory.newInstance().newXPath();
// get hourly elements that have tempC child element with value > 0 and weatherDesc child element with value = "rain"
String expression = "//hourly[tempC>0 and weatherDesc=\"rain\"]";
NodeList hours = (NodeList) xPath.compile(expression).evaluate(xmlDocument, XPathConstants.NODESET);
for (int i = 0; i < hours.getLength(); i++) {
System.out.println(hours.item(i) + " " + hours.item(i).getTextContent());
}
} catch (Exception e) {
e.printStackTrace();
}

I think you should create xsd from xml and generate JAXB classes.Using those JAXB class you can easily unmarshal the xml and process your logic.

How do I return a subsection of an XML request based on an XPath expression

I have written code that enables me to a subsection of an xml request based on a given XPath, however, it is only the value between the tags that are returned and not the tags.
I want both values and elements to be returned based on a given xpath.
For example, in this xml:
?xml version="1.0"?>
<company>
<staff1>
<name>john</name>
<phone>465456433</phone>
<email>gmail1</email>
<area>area1</area>
<city>city1</city>
</staff1>
<staff2>
<name>mary</name>
<phone>4655556433</phone>
<email>gmail2</email>
<area>area2</area>
<city>city2</city>
</staff2>
<staff3>
<name>furvi</name>
<phone>4655433</phone>
<email>gmail3</email>
<area>area3</area>
<city>city3</city>
</staff3>
</company>
my XPath would only return the value of the first staff element i.e.
John
465456433
gmail1
area1
city1
It does not return the tags associated to it i.e, it should return the following:
<staff1>
<name>john</name>
<phone>465456433</phone>
<email>gmail1</email>
<area>area1</area>
<city>city1</city>
</staff1>
Here is my code:
InputSource inputSource = new InputSource(new StringReader(xmlString));
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setNamespaceAware(true);
String RecordCategory;
Document doc = documentBuilderFactory.newDocumentBuilder().parse(inputSource);
// Create XPathFactory object
XPathFactory xpathFactory = XPathFactory.newInstance();
// Create XPath object
XPath xpath = xpathFactory.newXPath();
System.out.println("TESTING XPATH");
xpath.setNamespaceContext(new NamespaceContext() {
#Override
public String getNamespaceURI(String prefix) {
...
});
XPathExpression expr = xpath.compile("//staff1[1]");
Staff1 = (String) expr.evaluate(doc,XPathConstants.STRING);
System.out.println("staff1: " + staff1);
Anyone have any idea on what I could do to resolve this issue?

Your Java call to XPathExpression.evaluation() is returning the string value of the node selected by your XPath expression. If you instead want to return the node selected by your XPath expression, change
Staff1 = (String) expr.evaluate(doc, XPathConstants.STRING);
to
Node node = (Node) expr.evaluate(doc, XPathConstants.NODE);
See this answer for how to pretty print node.

DOM Parser query in JAVA

<subjectOf typeCode="SUBJ">
<annotation classCode="ACT" moodCode="EVN">
<realmCode code="QD" />
<code code="SPECIALNOTE"></code>
<text><![CDATA[<strong>** New York State approval pending. This test is not available for New York State patient testing **</br> ]]></text>
</annotation>
</subjectOf>
<subjectOf typeCode="SUBJ">
<annotation classCode="ACT" moodCode="EVN">
<realmCode code="QD" />
<code code="PREFERREDSPECIMEN"></code>
<text><![CDATA[2 mL Second void urine <strong>or </strong>2-hour urine <strong>or </strong> 2 mL Urine with no preservative]]></text>
</annotation>
</subjectOf>
In DOM parsing, how can I traverse through the above XML and get the <text> tag value depending upon a <code> tag attribute having a given value. For example, I want to get the following text:
<strong>** New York State approval pending. This test is not available
for New York State patient testing **</br>
...based on the <code> tag with a code attribute where value="SPECIALNOTE".
public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException, XPathExpressionException {
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true);
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse("xml.xml");
XPath xpath = XPathFactory.newInstance().newXPath(); // XPath Query for showing all nodes value
XPathExpression expr = xpath.compile("/testCodeIdentifier/subjectOf/subjectOf/annotation/code[#code='SPECIALNOTE']");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println("........"+nodes.item(i).getNodeValue()+"........");
}
}
}
Appreciate the help in advance...

First, your XPath expression has an error; subjectOf is repeated unnecessarily:
/subjectOf/subjectOf
Now, assuming you really do need a reference to the code node that precedes the target text element, then use the following:
XPathExpression expr = xpath.compile(
"/testCodeIdentifier/subjectOf/annotation/code[#code='SPECIALNOTE']");
Node node = (Node) expr.evaluate(doc, XPathConstants.NODE);
System.out.println(getNextElementSibling(node).getTextContent());
Where getNextElementSibling is defined as follows:
public static Node getNextElementSibling(Node node) {
Node next = node;
do {
next = next.getNextSibling();
} while ((next != null) && (next.getNodeType() != Node.ELEMENT_NODE));
return next;
}
A couple of notes about this:
The reason that getNextSibling did not originally work for you is (most likely) because the next sibling of the referenced code element is a text node, not an element node. (The whitespace between code and text is significant.) That's why we need getNextElementSibling.
We're selecting a single node, so we're using XPathConstants.NODE instead if XPathConstants.NODELIST
Note that you should probably just do as #Lukas suggests and modify your XPath expression to directly select the target text.
Here's how to get the text directly (as a String):
XPathExpression expr = xpath.compile(
"/testCodeIdentifier/subjectOf/annotation[code/#code='SPECIALNOTE']/text/text()");
String text = (String) expr.evaluate(doc, XPathConstants.STRING);
System.out.println(text);
Here's how to first get a reference to the element and then retrieve the contents of its CDATA section:
XPathExpression expr = xpath.compile(
"/testCodeIdentifier/subjectOf/annotation[code/#code='SPECIALNOTE']/text");
Node text = (Node) expr.evaluate(doc, XPathConstants.NODE);
System.out.println(text.getTextContent());

Fix your XPath expression like this:
/testCodeIdentifier/subjectOf/annotation[code/#code='SPECIALNOTE']/text
You could then, for instance, access the CDATA content using
Node.getTextContent();
UPDATE: The above XPath seemed correct at the time I posted it. In the meantime, you have completely changed your XML code and now, the XPath would read
/testCodeIdentifier/subjectOf/code/subjectOf/annotation[code/#code='SPECIALNOTE']/text
Or, because I am guessing that this question is so messy, it's still wrong, just do:
//annotation[code/#code='SPECIALNOTE']/text

Finally i have got the answer for my question by myself.... Below code is being working for my XML to be parsed...
XPath xpath = XPathFactory.newInstance().newXPath();
// XPath Query for showing all nodes value
XPathExpression expr = xpath.compile("//testCodeIdentifier/subjectOf/order/subjectOf/annotation/code[#code='SPECIALNOTE']/following-sibling::text/text()");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println(nodes.item(i).getNodeValue());
}
Thank you people who have ansewered in this post but this is a possible solution for it. Have a mark on it.

XPathExpression not evaluatng in the proper context?

I'm trying to parse some XML from the USGS.
Here's an example
The "parameterCd" parameter lists the 3 items of data I want back. I may or may not get all 3 back.
I'm doing this on an Android using the javax libraries.
In my code, I initially retrieve the 0-3 ns1:timeSeries nodes. This works fine. What I then want to do is, within the context of a single timeSeries node, retrieve the ns1:variable and ns1:values nodes.
So in my code below where I have:
expr = xpath.compile("//ns1:variable");
NodeList variableNodes = (NodeList) expr.evaluate(timeSeriesNode, XPathConstants.NODESET);
I would expect to only get back one node, since the evaluate SHOULD be happening in the context of the single timeSeriesNode that I'm passing in (according to the documentation). Instead, however, it returns all of the ns1:variable nodes for the document, however.
Am I missing something?
Here's the relevant portions...
XPathFactory factory = XPathFactory.newInstance();
XPath xpath = factory.newXPath();
xpath.setNamespaceContext(new InstantaneousValuesNamespaceContext());
XPathExpression expr;
NodeList timeSeriesNodes = null;
InputStream is = new ByteArrayInputStream(sourceXml.getBytes());
try {
expr = xpath.compile("//ns1:timeSeries");
timeSeriesNodes = (NodeList) expr.evaluate(new InputSource(is), XPathConstants.NODESET);
for(int timeSeriesIndex = 0;timeSeriesIndex < timeSeriesNodes.getLength(); timeSeriesIndex++){
Node timeSeriesNode = timeSeriesNodes.item(timeSeriesIndex);
expr = xpath.compile("//ns1:variable");
NodeList variableNodes = (NodeList) expr.evaluate(timeSeriesNode, XPathConstants.NODESET);
// Problem here. I've got all the variables, not the individual one I want.
for(int variableIndex = 0; variableIndex < variableNodes.getLength(); variableIndex++){
Node variableNode = variableNodes.item(variableIndex);
expr = xpath.compile("//ns1:valueType");
NodeList valueTypeNodes = (NodeList) expr.evaluate(variableNode, XPathConstants.NODESET);
}
}
} catch (XPathExpressionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

Try changing
//ns1:variable
to
.//ns1:variable
Even though, as the docs say, the expression is evaluated within the context of the current node, // is special and (unless modified) always means 'search the whole document from the root'. By putting the . in, you force the meaning you want, 'search the whole tree from this point downwards'.