SoapUI and Excel: empty values vs. no value - xpath

Question

I am using SoapUI Pro 4.5.2 to read data from spreadsheets, put them into Soap requests to my web service, and get responses back to write to a spreadsheet. It's working.
I have two fields in the input data pertinent to my question:
Middle name is defined as a string of 4 characters, and as minOccurs = 1 and maxOccurs = 1.
Postal extension code (the 4-digit number that is optional after the normal 5-digit code) is defined as a string of 4 digits. This field is optional, so it is marked as minOccurs=0 and maxOccurs=1.
When I use the SoapUI UI interface to send a request, this works fine; if there's no value for middle name, SoapUI generates an empty tag and sends it (I guess because of the minOccurs=1). If there's no value for PostalCode, it does not send any tag at all (I guess because of minOccurs=0).
When SoapUI reads data from an Excel spreadsheet, however, the response to the same data is an error indicating that the extended postal code value of '' is not legal, because it must be 4 digits. It appears that SoapUI generates an empty tag for the extended postal code when reading data from the spreadsheet, and sends it.
I found the "Remove Empty Content" option for SoapUI requests, default to false. I set it to true, and now get an error back from validation indicating that middle name is required but not found. I'm guessing that the remove empty content removed all the empty content (reasonable enough), and middle name has to be there, even if empty, because of the minOccurs=1.
Do I have any way out of this tail-chasing problem? I suppose I'm looking for something like a conditional for the output of the postal extension code, so I can eliminate it if it's empty, even if reading values from the spreadsheet.
I am also curious if there are XSD fixes, but I greatly prefer a fix that doesn't involve changing the XSD -- that becomes a political matter.
EDIT FOR DETAIL:
To put input into the request: I have used the SoapUI UI to choose "properties" from the input spreadsheet for each of the input fields; when that's done, one ends up with values in the request fields like:
${SpreadsheetInput#FrstNm}
Where SpreadsheetInput is the name of the datasource step reading the spreadsheet, and FrstNm is one of the properties. I do this with the "Get Data" option off the popup menu you get by right-clicking the request input field, but there may be other ways.

Answer 1

So first your problem:
Remember that internally to SoapUI almost everything is a string. Doing something like:
<postCode>${SpreadsheetInput#PostCode}</postCode>
in your SOAP request, assuming PostCode is either blank or does not exist outright, will expand to:
<postCode></postCode>
and SoapUI will even optimize it to:
</postCode>
Then your validation kicks in, which says you do not need to provide this element, but if you do, it had better be 4-characters long. Which the above fails.
The solution:
You need to pragmatically (meaning you will have to write Groovy code) create this node in your request. There are several ways to handle this. The quick and dirty is with a Groovy step, that goes something like:
def postCode = context.expand('${SpreadsheetInput#PostCode}').trim()
if (postCode != null && postCode != '')
testRunner.testCase.setpropertyValue("postCodeNode", "<postCode>" + postCode + "</postCode>")
else
testRunner.testCase.setpropertyValue("postCodeNode", "")
Then in your request replace the original:
<postCode>${SpreadsheetInput#PostCode}</postCode>
with just:
${#TestCase#postCodeNode}
Notice, the XML node elements are part of the SoapUI property! Again: everything in SoapUI is just a plain string.
If you want something more hard-core, have a look at
dynamically create elements in a SoapUI request. This is mine.