As I Walk Along I Wonder...

Having an Orchestration where I perform a mapping and try to set a promoted property to some value for either correlation or business use, I sometimes encounter this error:

A failure occurred while evaluating the property MacawSchemas.PropertySchema.SomeField against the message part data. The message part data does not contain at least one of the nodes specified by the XPath expression (listed below) that corresponds to the property.

It ofcourse means BizTalk cannot find the property I'm refering to by using the XPath originally specified when the property was promoted (in the annotation within the document schema). However, I was certain I had the XPath setup correctly.

After some testing, it turned out I made the mistake of assuming the field would be available, while in fact, the mapper didn't produce the field in creating the message, as it had neither an inbound link (naturally), nor a default value.

Setting a "space" character to be it's default value in the mapping target is all I needed to get an empty element generated and for the Orchestration to work......

Can't win 'em all :-o