Hi Mike

Yes the fixed attribute and all the other schema facets are only used when validating.  The dfdl:checkConstraints() function is provided to allow a dfdl:assert or dfdl:discriminator to check that the value of an element obeys its schema constraints.

Regards

Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh@uk.ibm.com
tel:+44-1962-815848



From:        Mike Beckerle <mbeckerle.dfdl@gmail.com>
To:        dfdl-wg@ogf.org
Date:        05/09/2012 16:32
Subject:        [DFDL-WG] clarification wanted: fixed values
Sent by:        dfdl-wg-bounces@ogf.org

---

The spec states that the fixed facet is only used for validation.

That is, it works like default in that it supplies a default that can be used when parsing and unparsing, but the comparison of an existing data value with the schema-specified fixed value is only done for validation. This means that a value not agreeing with the fixed value specified in the schema would never cause backtracking.

Is this right? It seems awkward to me that I have to use a dfdl:assert annotation to achieve this. That said, however, I can achieve the behaviour I need. it's just more verbose than I wanted.

Is this what the current IBM implementation does?

Thanks

--
Mike Beckerle | OGF DFDL WG Co-Chair 
Tel:  781-330-0412
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