BizTalk BAM - manually editing BTT XPath to return just the First instance of a Message Payload property?

Question

Hi!

We have a preference for using TPE for BAM tracking since it can be deployed independently of our orchestrations.

However, at one point in our process, we need to track a message payload property which has a 1:N relationship with the Root XML Element of the message.

Despite the 1:N relationship, extracting just the first value of this property will be sufficient for our tracking needs.

As usual, if we attempt to track this, then the following XLANG message is logged:

AmbiguousXPathException - The result set for the XPath expression ... contains more than a single node

We have tried to modify the BTT XPath directly to select just the first instance of this Property

I've tried

'XPath="//*[local-name()='Property' and namespace-uri()='{URI}' ...]/[1]' but then get the error "Expression must evaluate to a node-set"

and more simply '//Property[1]' and '//Property[position() = 1]' Give no error, but this doesn't pull out my property either.

Lastly, can anyone explain the difference between the XPath and SomXPath in the BTT file?

Thanks in Advance!

Stuart

Answer 1

It is like shooting in the dark without any XML document provided, but you may try this:

(//*[local-name()='Property' and namespace-uri()='{URI}' ...])[1]

It is a FAQ that //x[1] does't select one node, while (//x)[1] does.

The first means: every element named x, that is the first child of its parent.

The second means: the first element x in the document.