From: Mike Beckerle <mbeckerle.dfdl@gmail.com>
To: Bradd Kadlecik <braddk@us.ibm.com>
Cc: DFDL-WG <dfdl-wg@ogf.org>
Date: 10/16/2019 04:50 PM
Subject: [EXTERNAL] Re: [DFDL-WG] DFDL inputValueCalc restrictions
So you are suggesting this:
<element name="myOVC" type="xs:int" dfdl:outputValueCalc="{ ../myIVC + 3 }" />
<element name="myIVC" type="xs:int" dfdl:inputValueCalc="{ compute here }" default="0"/><!-- default only used when unparsing -->
That's not unreasonable.
Question: Can the behavior you need be represented by way of a test for existence of the IVC element?
<element name="myOVC" type="xs:int" dfdl:outputValueCalc="{ if (fn:not(fn:exists(../myIVC))) then 0 else ....do the real computation here.... }"/>
<!-- an optional IVC element -->
<choice>
<sequence> <!-- IVC can't be root of a choice branch so workaround -->
<element name="myIVC" dfdl:inputValueCalc="{ compute here }"/>
</sequence>
<sequence/> <!-- nothing at all is the other alternative -->
</choice>
That's clumsier, but does achieve, I think, the same behavior without depending on defaulting. It does depend on fn:exists and fn:not functions.
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com
Please note: Contributions to the DFDL Workgroup's email discussions are subject to the OGF Intellectual Property Policy
On Wed, Sep 25, 2019 at 11:49 AM Bradd Kadlecik <braddk@us.ibm.com> wrote:
- Hello,
I have one item I'd like to discuss at some point regarding inputValueCalc and not allowing the default property to be specified. I have a use case where the default property would be useful for unparse. It makes perfect sense to not allow it for outputValueCalc however.
The use case is in forming a connection between an inputValueCalc element and an outputValueCalc element where the incoming document might not contain the inputValueCalc element for unparse and a default value would be desired for the outputValueCalc use. This is an item our customers using DFDL would like to make use of but don't want to require the element to always exist for unparse.
| Regards, Bradd Kadlecik z/TPF Development |