Igor Kromin |   Consultant. Coder. Blogger. Tinkerer. Gamer.

I've written previously about fixing HL7 CDA schema compilation with XJC, now that I've been looking at FHIR it seems that there are name collisions in that schema too. The actual problem arises out of the W3C XHTML 1.0 Schema and not the FHIR schema per se.

This is the kind of error that XJC throws whenever trying to compile the FHIR schema:
 XJC Error
Error while parsing schema(s).Location [ fhir-xhtml.xsd{48,2902}].
com.sun.istack.SAXParseException2; systemId: fhir-xhtml.xsd; lineNumber: 48; columnNumber: 2902; Property "Lang" is already defined. Use <jaxb:property> to resolve this conflict.


Ok so that says that "Lang" is already defined and looking at that part of the XSD reveals this...
 XSD
<xs:attributeGroup name="i18n">
<xs:attribute name="lang" type="LanguageCode"/>
<xs:attribute ref="xml:lang"/>
...


It's pretty obvious why XJC would complain. There's a name collisions between the xml:lang reference and the lang attribute, both would get mapped to a variable named 'lang' in the generated Java code.

To fix it, it's just a matter of telling XJC to rename the xml:lang reference to 'xmlLang' when generating Java code while leaving the lang attribute as is. The following bindings would be suitable, see my CDA article linked above for the full binding file definition:
 Bindings
<jaxb:bindings schemaLocation="http://hl7.org/fhir/2016May/fhir-xhtml.xsd">
<jaxb:bindings node="//xs:attributeGroup[@name='i18n']/xs:attribute[@ref='xml:lang']">
<jaxb:property name="xmlLang"/>
</jaxb:bindings>
<jaxb:bindings node="//xs:element[@name='bdo']/xs:complexType/xs:complexContent/xs:extension/xs:attribute[@ref='xml:lang']">
<jaxb:property name="xmlLang"/>
</jaxb:bindings>
</jaxb:bindings>


Here's an answer from StackOverlow that is similar in nature and covers it in more detail.



Then it's just a matter of telling XJC that you want to use a binding file and the FHIR schema should compile!

-i

Skip down to comments...
Hope you found this post useful...

...so please read on! I love writing articles that provide beneficial information, tips and examples to my readers. All information on my blog is provided free of charge and I encourage you to share it as you wish. There is a small favour I ask in return however - engage in comments below, provide feedback, and if you see mistakes let me know.

If you want to show additional support and help me pay for web hosting and domain name registration, donations, no matter how small, are always welcome!

Use of any information contained in this blog post/article is subject to this disclaimer.
 
comments powered by Disqus
Other posts you may like...