Camel retrieving xml tag name using xpath

Question

I'm not able to get the xpath expression to work. I'm using Camel 2.15.1. Any help would be greatly appreciated.

I've tried the following

<xpath>name(//*[1])='PPR_PC2'</xpath>
<xpath>name("//*[local-name()='PPR_PC2')</xpath>
<xpath>//PPR_PC2</xpath>

My xml file

<?xml version="1.0" encoding="UTF-8"?>
<PPR_PC2 xmlns="urn:hl7-org:v2xml">
   <MSH>
      <MSH.1>|</MSH.1>
      ...
      ...
    </MSH>
    ...
    ...
</PPR_PC2>

My Camel route

<route id="_route_1">
    <from uri="activemq:queue:myQIN"/>

    <doTry>
        <choice>
            <when>
                // This path works without having namespace 
                <xpath>name(//*[1])='PPR_PC2'</xpath>
                <to uri="xslt:transform/stylesheet.xsl"/>
                <to uri="..."/>
            </when>
            <otherwise> ... </otherwise>
        </choice>
        <doCatch> ... </doCatch>
    </doTry>
</route>

This is the error I'm getting

[thread #1 - JmsConsumer[myQIN]] EndpointMessageListener
    WARN  Execution of JMS message listener failed. 
    Caused by: [org.apache.camel.builder.xml.InvalidXPathExpression - Invalid xpath: name(//*[1])='PPR_PC2'. 
    Reason: javax.xml.xpath.XPathExpressionException: net.sf.saxon.trans.XPathException: 
    A sequence of more than one item is not allowed as the first argument of name() (<PPR_PC2/>, <MSH/>, ...) ]
org.apache.camel.builder.xml.InvalidXPathExpression: 
    Invalid xpath: name(//*[1])='PPR_PC2'. 
    Reason: javax.xml.xpath.XPathExpressionException: net.sf.saxon.trans.XPathException: 
    A sequence of more than one item is not allowed as the first argument of name() (<PPR_PC2/>, <MSH/>, ...)

Michael Kay · Accepted Answer · 2016-09-29 14:16:34Z

1

The error message

A sequence of more than one item is not allowed as the first argument of name()

suggests that when you wrote

name(//*[1])

(which selects every element that is the first child of its parent)

you probably meant

name((//*)[1])

(which selects the first element in the document)

though that would give you exactly the same as

name(/*)

answered Sep 29, 2016 at 14:16

Michael Kay

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Community · Accepted Answer · 2017-05-23 12:10:19Z

0

Declare the namespace and use it. Note the xmlns below.

<route id="_route_1" xmlns:hl7="urn:hl7-org:v2xml">
    <from uri="activemq:queue:myQIN"/>

    <doTry>
        <choice>
            <when>
                <xpath>/hl7:PPR_PC2</xpath>
                <to uri="xslt:transform/stylesheet.xsl"/>
                <to uri="..."/>
            </when>
            <otherwise> ... </otherwise>
        </choice>
        <doCatch> ... </doCatch>
    </doTry>
</route>

You can pick any prefix you like, but you have to pick a prefix in order to be able to declare and use a namespace. I chose hl7 for the example.

Declare the namespace higher up in your XML file to be able to use it in multiple places.

Also read how to use xpath in camel-context.xml to check if a particular node is exist or not

edited May 23, 2017 at 12:10

CommunityBot

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answered Sep 29, 2016 at 13:24

Tomalak

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Comments

pacholik · Accepted Answer · 2016-10-01 11:57:55Z

0

Try using :

Namespaces ns = new Namespaces("cus","http://...");

ns.xpath("//MSH.1/text()", java.lang.String.class)

edited Oct 1, 2016 at 11:57

pacholik

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answered Sep 29, 2016 at 13:41

Prateek Mehta

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