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From "Siano, Stephan" <stephan.si...@sap.com>
Subject RE: Question about type converter logic
Date Tue, 13 Jan 2015 07:30:47 GMT
Hi Claus,

Sure, I will contribute the converter to camel-saxon, once I get it running, but at least
in my unit test it never gets executed (so I obviously do something wrong). How is type converter
selection done?

Best regards
Stephan

-----Original Message-----
From: Claus Ibsen [mailto:claus.ibsen@gmail.com] 
Sent: Dienstag, 13. Januar 2015 08:16
To: dev
Subject: Re: Question about type converter logic

You can add a type converter to camel-saxon that converts a NodeInfo
to DOMSource which Camel ought to use then.

On Tue, Jan 13, 2015 at 8:12 AM, Siano, Stephan <stephan.siano@sap.com> wrote:
> Hi,
>
> I am trying to figure out how to write a type converter that can convert e.g. from net.sf.saxon.om.NodeInfo
to DOMSource. The problem with this is that the NodeInfo implements (javax.xml.transform.Source),
so the XmlConverter from camel-core will kick in.
>
>
> The relevant coding looks like that (and as NodeInfo is not DOMSource, SAXSource, StreamSource,
or StAXSource the converter will return null)
>     /**
>      * Converts the source instance to a {@link DOMSource} or returns null if the conversion
is not
>      * supported (making it easy to derive from this class to add new kinds of conversion).
>      */
>     @Converter
>     public DOMSource toDOMSource(Source source) throws ParserConfigurationException,
IOException, SAXException, TransformerException {
>         if (source instanceof DOMSource) {
>             return (DOMSource) source;
>         } else if (source instanceof SAXSource) {
>             return toDOMSourceFromSAX((SAXSource) source);
>         } else if (source instanceof StreamSource) {
>             return toDOMSourceFromStream((StreamSource) source);
>         } else if (source instanceof StAXSource) {
>             return toDOMSourceFromStAX((StAXSource)source);
>         } else {
>             return null;
>         }
>     }
>
> I don't think that changing the XmlConverter is a good ideas (as it would introduce a
Saxon dependency to camel-core), but the comment at least implies that it should be possible
to extend the converter somewhere else (e.g. in camel-saxon). However, I couldn't figure out
how to do this.
>
> So far I have tried to create a SaxonConverter that extends XMLConverter, overrides the
toDOMSource method of XmlConverter and creates a new converter method from NodeInfo to DOMSource,
but those methods never get invoked in my unit tests (and the type conversion keeps returning
null).
>
> Is there any documentation about how type converters are selected and how this extension
could be done (or could someone explain that to me)? How is this "making it easy to derive
from this class to add new kinds of conversion" comment meant?
>
> Best regards
> Stephan



-- 
Claus Ibsen
-----------------
Red Hat, Inc.
Email: cibsen@redhat.com
Twitter: davsclaus
Blog: http://davsclaus.com
Author of Camel in Action: http://www.manning.com/ibsen
hawtio: http://hawt.io/
fabric8: http://fabric8.io/
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