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| XPath in Java returns List object for text() node ? |
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| Cogito-Ergo-Sum |
 Posted: Mon Apr 11, 2011 11:38 pm Post subject: XPath in Java returns List object for text() node ? |
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Master
Joined: 07 Feb 2006
Posts: 293
Location: Bengaluru, India
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I would like to know, whether it is incorrect to expect a String object instead of a List object from a text() node in an XPath expression from evaluateXPath(MbXPath) ? Conversely, in what circumstances, can evaluateXPath(MbXPath) return a String or say, a Double as mentioned in the javadoc ?
With this code :
| Code: |
mbx = new MbXPath("/a/b/c/text()");
mbx.addNamespacePrefix("tns", "example.com") ;
String s = (String) inMsg.evaluateXPath(mbx) ; |
I get an exception as shown below :
| Code: |
| Apr 11 22:50:19 nsubrahm WebSphere Broker v7001[4552]: (NSUBRAHM.BRKR.default)[8]BIP4367E: The method 'evaluate' in Java node 'JC01' has thrown the following exception: [b]java.lang.ClassCastException: java.util.Arrays$ArrayList incompatible with java.lang.String[/b]. : NSUBRAHM.BRKR.9ea86cb8-2e01-0000-0080-ec35aac0b0a5: /build/S700_P/src/DataFlowEngine/PluginInterface/com_ibm_broker_plugin_CMbService.cpp: 1845: ImbJavaExceptionUtils::throwableToNativeException: : |
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ALL opinions are welcome.
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Debugging tip:When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.
---Sherlock Holmes |
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| kimbert |
| Posted: Tue Apr 12, 2011 11:46 am Post subject: |
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Jedi Council
Joined: 29 Jul 2003
Posts: 5542
Location: Southampton
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I expect it depends on whether the XPath expression matched a single node or a list of nodes. And if a single node was matched, I would expect a simple data type for a node with a value, but a list otherwise.
If you posted your XPath expression and the output of a Trace node then I could be more specific. |
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| rekarm01 |
| Posted: Tue Apr 12, 2011 6:02 pm Post subject: Re: XPath in Java returns List object for text() node ? |
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Grand Master
Joined: 25 Jun 2008
Posts: 1415
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| Cogito-Ergo-Sum wrote: |
| I would like to know, whether it is incorrect to expect a String object instead of a List object from a text() node in an XPath expression from evaluateXPath(MbXPath)? |
Yes, it is incorrect to expect that. text() always returns a node-set, regardless of the number of matching text nodes.
| Cogito-Ergo-Sum wrote: |
| Conversely, in what circumstances, can evaluateXPath(MbXPath) return a String or say, a Double as mentioned in the javadoc? |
The javadoc also provides a link to the w3c recommendation for XPath 1.0, which specifies exactly how to evaluate XPath expressions. |
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| Cogito-Ergo-Sum |
| Posted: Tue Apr 12, 2011 6:52 pm Post subject: |
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Master
Joined: 07 Feb 2006
Posts: 293
Location: Bengaluru, India
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| Quote: |
| text() always returns a node-set, regardless of the number of matching text nodes. |
oh....yes, now I understand. For example, I used this document
| Code: |
| <root><tag1><tag2>This is some data of <date>Apr-13-2011</date> as shown in this document.</tag2></tag1></root> |
and applied XPath as
| Code: |
| /root/tag1/tag2/text() |
which returns two text() nodes as
| Code: |
This is some data of
as shown in this document |
Thanks !
_________________
ALL opinions are welcome.
-----------------------------
Debugging tip:When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.
---Sherlock Holmes |
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| McueMart |
| Posted: Thu Dec 13, 2012 11:07 am Post subject: |
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Chevalier
Joined: 29 Nov 2011
Posts: 490
Location: UK...somewhere
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Just digging this post up so it might help someone in future....
As the OP found out, selecting the text node using text() doesn't cause evaluateXPath(MbXPath) to return a String. If you want it to return a string you can do something like:
| Code: |
mbx = new MbXPath("string(/root/tag1/tag2)");
String s = (String) inMsg.evaluateXPath(mbx) ;
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I appreciate this is just basic xpath but it took me more than a couple of minutes to figure it out  |
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