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MQSeries.net Forum Index » WebSphere Message Broker (ACE) Support » Using Xpath in a JCN in an MBElement Returning a Null value

Using Xpath in a JCN in an MBElement Returning a Null value

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satquick

Posted: Wed May 28, 2014 12:27 pm Post subject: Using Xpath in a JCN in an MBElement Returning a Null value

Newbie

Joined: 28 May 2014
Posts: 4

Hi Everyone.

I am new in this forum and recently I got a big dilemma with this:

using a JCN

The flow is as follows:

MQInput ==> Trace ==> JNC ==> Trace==>MQOutput

I added these 2 TRace Nodes in order to track the values in the original Message by using the Correlation Name ${Root}.

Now this is the issue in question:

//1.-Xpath expresion to get the first customer in the XML
List customer = (List)inMessage.evaluateXPath("customers/customer[1]");
//2.-obtaining the first element contained in the list
MbElement customerElement= (MbElement)customer.get(0);
//3.-using the method getFirstElementByPath which one returns the value
String nameByFirstElement = customerElement.getFirstElementByPath("name").getValueAsString();
//4.-using the MBElement this Xpath Evaluation fails and returns null
String nameByXPath = (String)customerElement.evaluateXPath("string(/customer/name/text())");

This is the XML used:

Code:

<customers>
<customer id="12345">
<name>George </name>
<LastName>Lopez</LastName>
<address>
<street>Av. Inventada #10</street>
<city></city>
<state></state>
<country>Mexico</country>
</address>
</customer>

<customer id="123456">
<name>Adrian</name>
<LastName>Lopez</LastName>
<address>
<street>Av. Inventada #10</street>
<city>Zapopan</city>
<state>Jalisco</state>
<country>Mexico</country>
</address>
</customer>
</customers>

The first XPath in point number 1 returns correctly the first set of the XML

Code:

point number 3 works correctly using the method getFirstElementByPath in MbElement the value of name is returned , but when I try to get the same value using XPATH in MBELement I got a null Value!!

String nameByXPath = (String)customerElement.evaluateXPath("string(/customer/name/text())");

what is the correct XPATH expresion that should I need to use ? or Am doing something wrong?

Please need your advice!!!

fjb_saper

Posted: Wed May 28, 2014 12:55 pm Post subject:

Grand High Poobah

Joined: 18 Nov 2003
Posts: 20768
Location: LI,NY

I don't think having "string" is the xpath is correct...

Have you tried:

Code:

String nameByXPath = (String)customerElement.evaluateXPath("/customer[1]/name[1]/text()");

Have fun

_________________
MQ & Broker admin

kimbert

Posted: Wed May 28, 2014 1:41 pm Post subject:

Jedi Council

Joined: 29 Jul 2003
Posts: 5543
Location: Southampton

Quote:

I don't think having "string" is the xpath is correct...

It looks like an XPath 'constructor' for xs:string. Whether it is correct depends on whether the XML Schema namespace ( usual prefix 'xs' or 'xsd' ) has been bound to the empty prefix in the namespace settings associated with the query.
_________________
Before you criticize someone, walk a mile in their shoes. That way you're a mile away, and you have their shoes too.

ganesh

Posted: Wed May 28, 2014 3:11 pm Post subject:

Master

Joined: 18 Jul 2010
Posts: 294

Quote:

what is the correct XPATH expresion that should I need to use ? or Am doing something wrong?

There are several tools that can give you an xpath of an element, you might even find a free online tool to get xpath's.

satquick

Posted: Wed May 28, 2014 4:28 pm Post subject:

Newbie

Joined: 28 May 2014
Posts: 4

Hi jfb_saper ! I have already tried and in the way that you indicated it, I need to receive the response in an ArrayList as follows:

List nameValue =(List)inMessage.evaluateXPath("customers/customer[1]/name[1]/text()");

I got null either =) by the way I am using WMBT 8.0.0.1

fjb_saper wrote:

I don't think having "string" is the xpath is correct...

Have you tried:

Code:

String nameByXPath = (String)customerElement.evaluateXPath("/customer[1]/name[1]/text()");

Have fun

satquick

Posted: Wed May 28, 2014 4:46 pm Post subject:

Newbie

Joined: 28 May 2014
Posts: 4

ganesh wrote:

Quote:

what is the correct XPATH expresion that should I need to use ? or Am doing something wrong?

There are several tools that can give you an xpath of an element, you might even find a free online tool to get xpath's.

I did some modifications and now I have this:

Code:

//taking the String value directly from the Message Assembly this works!
String nameValue=(String)inMessage.evaluateXPath("string(customers/customer[1]/name)");
//Xpath expresion to get the first customer in the XML
List customer = (List)inMessage.evaluateXPath("customers/customer[1]");
//obtaining the first element contained in the list
MbElement customerElement= (MbElement)customer.get(0);
//using the MBElement this Xpath Evaluation fails and returns null this does not work!
String nameByXPath = (String)customerElement.evaluateXPath("string(customer/name)");

If I try to get the name value directly from the Message Assembly then I get the value using XPATH(this works ):

Code:

String nameValue =(String)inMessage.evaluateXPath("string(customers/customer[1]/name)");

but If I try it to get the value from a MbMessage created on the XPath before it returns null value even if in the debug mode it says that the MbElement contains data.

Code:

//Xpath expresion to get the first customer in the XML
List customer = (List)inMessage.evaluateXPath("customers/customer[1]");
//obtaining the first element contained in the list
MbElement customerElement= (MbElement)customer.get(0);
//using the MBElement this Xpath Evaluation fails and returns null this does not work!
String nameValue=(String)inMessage.evaluateXPath("string(customer/name)");

Also if I try to convert the Body MbElement to String this does work as well:

Code:

//obtaining the XMLNSC DOMAIN that represents the XML
MbElement xmlnsc = inMessage.getRootElement().getLastChild();
//Converting the XMLNSC to String
String value= new String((byte[])xmlnsc.toBitstream(null, null, null, 0, 0, 0));

but If I try to convert the MbElement created using the Xpath I got a beautiful Message: Unable to resolve message exception:

Quote:

(0x01000000:Name ):Insert = (
(0x03000000:NameValue):Type = 5 (INTEGER)
(0x03000000:NameValue):Text = '<com.ibm.broker.plugin.MbUserException class:com.ibm.customers.Customer_MessageFlow_JavaCompute method:evaluate() source: key: message: Unable to resolve message: Source: Key: >' (CHARACTER)
)

Code:

//List customer = (List)inMessage.evaluateXPath("customers/customer[1]");
List customer = (List)inMessage.evaluateXPath("customers/customer[1]");

//obtaining the first element contained in the list
MbElement customerElement= (MbElement)customer.get(0);

//convert it to String
String customerElementValue =new String((byte[])customerElement.toBitstream(null, null, null, 0, 0, 0));

mqjeff

Posted: Mon Jun 02, 2014 8:34 am Post subject:

Grand Master

Joined: 25 Jun 2008
Posts: 17447

Your second xpath that returns null is looking for the equivalent of /customers/customer[1]/customer/name

That's why it returns null.

satquick

Posted: Wed Jun 11, 2014 12:41 pm Post subject:

Newbie

Joined: 28 May 2014
Posts: 4

mqjeff wrote:

Your second xpath that returns null is looking for the equivalent of /customers/customer[1]/customer/name

That's why it returns null.

Thanks mqjeff! yeah !! that worked!

This is the correct way:

Code:

String nameByXPath = (String)customerElement.evaluateXPath("string(name)");

This is the complete code:

Code:

//Xpath expresion to get the first customer in the XML
      //List customer = (List)inMessage.evaluateXPath("customers/customer[1]");
      String nameValue =(String)inMessage.evaluateXPath("string(customers/customer[1]/name)");


      //List customer = (List)inMessage.evaluateXPath("customers/customer[1]");
      List customer = (List)xmlnsc.evaluateXPath("customers/customer[1]");
      //obtaining the first element contained in the list
      MbElement customerElement= (MbElement)customer.get(0);
      //using the method getFirstElementByPath which one returns the value
      String nameByFirstElement = customerElement.getFirstElementByPath("name").getValueAsString();
      //using the MBElement this Xpath Evaluation fails and returns null
      String nameByXPath = (String)customerElement.evaluateXPath("string(name)");

[/code]

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