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https://issues.apache.org/jira/browse/SYNAPSE-557?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Bill Harts updated SYNAPSE-557:
-------------------------------

    Description: 
Problem:
An XPath expression in my synapse.xml configuration file is unable to retrieve 
an XML attribute from a message.  Example:

<log level="custom">
  <property name="sessID"  
expression="//ns:LoginResponse/ns:LoginResponseData/@sessionID" 
xmlns:ns="http://www.test.com/ns"; />
</log>

The message body is:
 <soapenv:Body>
  <ns:LoginResponse xmlns:ns="http://www.test.com/ns";>
   <ns:LoginResponseData sessionID="250446AD43C0EEF3ED2F3172F8FA0A3D" 
statusCode="0"/>
  </ns:LoginResponse>
 </soapenv:Body>

In this case the log mediator always returns null for the sessID variable.

Cause:
After poking around in a bunch of modules I believe that these XPath 
expressions are being handled in module synapseXPath.java.  Specifically there 
is a call in stringValueOf(MessageContext synCtx) to BaseXPath.evaluate() which 
returns a List of element pointers retrieved by the XPath expression.  The 
function then correctly checks each element to to determine if it is of type 
OMTextImpl, OMElementImpl or OMDocumentImpl but when an attribute has been 
found evaluate() returns an attribute of type DocumentNavigator$OMAttributeEx.  
It appears that there is no code in stringValueOf() to handle this type of 
pointer.

Solution:
I added the following code to synapseXpath.java::stringValueOf at line 206:

                    ...
                    } else if (o instanceof OMAttributeEx) {
                        textValue.append( 
((OMAttributeEx)o).getAttributeValue());
                   }
                   ...

Also, since the type OMAttributeEx is an inner class of type DocumentNavigator 
I needed to add an import statement in SynapseXPath.java:

import org.apache.axiom.om.xpath.DocumentNavigator.OMAttributeEx;

Unfortunately, OMAtributeEx is defined as private to class DocumentNavigator so 
I had to declare class and constructor OMAttributeEx as public in the module 
DocumentNavigator.java in the Axiom project module axiom-api.jar.  

  was:
Problem:
An XPath expression in my synapse.xml configuration file is unable to retrieve 
an XML attribute from a message.  Example:

<log level="custom">
  <property name="sessID"  
expression="//cfl:LoginResponse/cfl:LoginResponseData/@sessionID" 
xmlns:cfl="http:www.test.com/cfl" />
</log>

The message body is:
 <soapenv:Body>
  <cfl:LoginResponse xmlns:cfl="http://www.test.com/cfl";>
   <cfl:LoginResponseData sessionID="250446AD43C0EEF3ED2F3172F8FA0A3D" 
statusCode="0"/>
  </cfl:LoginResponse>
 </soapenv:Body>

In this case the log mediator always returns null for the sessID variable.

Cause:
After poking around in a bunch of modules I believe that these XPath 
expressions are being handled in module synapseXPath.java.  Specifically there 
is a call in stringValueOf(MessageContext synCtx) to BaseXPath.evaluate() which 
returns a List of element pointers retrieved by the XPath expression.  The 
function then correctly checks each element to to determine if it is of type 
OMTextImpl, OMElementImpl or OMDocumentImpl but when an attribute has been 
found evaluate() returns an attribute of type DocumentNavigator$OMAttributeEx.  
It appears that there is no code in stringValueOf() to handle this type of 
pointer.

Solution:
I added the following code to synapseXpath.java::stringValueOf at line 206:

                    ...
                    } else if (o instanceof OMAttributeEx) {
                        textValue.append( 
((OMAttributeEx)o).getAttributeValue());
                   }
                   ...

Also, since the type OMAttributeEx is an inner class of type DocumentNavigator 
I needed to add an import statement in SynapseXPath.java:

import org.apache.axiom.om.xpath.DocumentNavigator.OMAttributeEx;

Unfortunately, OMAtributeEx is defined as private to class DocumentNavigator so 
I had to declare class and constructor OMAttributeEx as public in the module 
DocumentNavigator.java in the Axiom project module axiom-api.jar.  


Saliya Ekanayake has pointed out that OMAttributeEx implements the OMAttribute 
interface so we can actually check for instanceof OMAttribute.  This way we 
don't have to change the access modifiers in Axis2 and don't need an additional 
import.  Changed code:

                    ...
                    } else if (o instanceof OMAttribute) {
                        textValue.append( ((OMAttribute)o).getAttributeValue());
                   }
                   ...

I will submit a patch file.

Bill

> XPath doesn't return attribute value
> ------------------------------------
>
>                 Key: SYNAPSE-557
>                 URL: https://issues.apache.org/jira/browse/SYNAPSE-557
>             Project: Synapse
>          Issue Type: Bug
>          Components: Core
>            Reporter: Bill Harts
>
> Problem:
> An XPath expression in my synapse.xml configuration file is unable to 
> retrieve an XML attribute from a message.  Example:
> <log level="custom">
>   <property name="sessID"  
> expression="//ns:LoginResponse/ns:LoginResponseData/@sessionID" 
> xmlns:ns="http://www.test.com/ns"; />
> </log>
> The message body is:
>  <soapenv:Body>
>   <ns:LoginResponse xmlns:ns="http://www.test.com/ns";>
>    <ns:LoginResponseData sessionID="250446AD43C0EEF3ED2F3172F8FA0A3D" 
> statusCode="0"/>
>   </ns:LoginResponse>
>  </soapenv:Body>
> In this case the log mediator always returns null for the sessID variable.
> Cause:
> After poking around in a bunch of modules I believe that these XPath 
> expressions are being handled in module synapseXPath.java.  Specifically 
> there is a call in stringValueOf(MessageContext synCtx) to 
> BaseXPath.evaluate() which returns a List of element pointers retrieved by 
> the XPath expression.  The function then correctly checks each element to to 
> determine if it is of type OMTextImpl, OMElementImpl or OMDocumentImpl but 
> when an attribute has been found evaluate() returns an attribute of type 
> DocumentNavigator$OMAttributeEx.  It appears that there is no code in 
> stringValueOf() to handle this type of pointer.
> Solution:
> I added the following code to synapseXpath.java::stringValueOf at line 206:
>                     ...
>                     } else if (o instanceof OMAttributeEx) {
>                         textValue.append( 
> ((OMAttributeEx)o).getAttributeValue());
>                    }
>                    ...
> Also, since the type OMAttributeEx is an inner class of type 
> DocumentNavigator I needed to add an import statement in SynapseXPath.java:
> import org.apache.axiom.om.xpath.DocumentNavigator.OMAttributeEx;
> Unfortunately, OMAtributeEx is defined as private to class DocumentNavigator 
> so I had to declare class and constructor OMAttributeEx as public in the 
> module DocumentNavigator.java in the Axiom project module axiom-api.jar.  

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