Re: Transform POJO/XML into another POJO/XML using Freemarker ????

Tuesday, July 1, 2008, 12:19:50 PM, cmoulliard wrote:

> Hi,
>
> I would like to know if it makes sense to use Freemarker to transform/map a
> POJO into another POJO (idem but for XML to XML) ?

FreeMarker's input can be anything (POJO-s), but the output is
designed to be text. So in principle you can't do what you want. But,
you could write some custom directives (see TemplateTransformModel and
#macro) that instead of printing to the output, build a tree of POJO-s
inside a special variable (that only you know is special) of the
data-model. Of course, then directives like #escape and
#attempt/#recover will not do anything... nor plain static-text nor
interpolation-in-static-text will (unless you use a special Writer
that somehow contributes to the POJO building). Also the
object-wrapping feature will become rather an annoyance than a useful
feature in this case, since you don't really have a separate
"presentation world" and "business logic world" here (so you will have
to un-wrap in the TemplateTransformModel-s). So it's a bit tricky, but
doable. I'm not sure if it's practical to do it though. If you will
need only a dozen of TemplateTransformModel-s but a lot of templates
(and/or #macros), then it can be practical. Then it will look like a
terser form of XML describing the POJO (plus ifs, loops, etc), only it
directly outputs the resulting POJO, so no need for JAXB and like.

> If this is the case, How can I achieve this ?
>
> Reason : We have a solution able to process different messages in entry but
> created according to different format (csv, fixed-length, XML, ...). The
> existing solution has been designed around a commercial solution but my boss
> would like to avoid to use it in the future. So, two scenario exist today to
> process the messages and tranform them to fit the information into our
> internal data model which is generic for all the messages
>
> 1) XML to XML
> Transform (or encapsulate) all the incoming messages into a XML stream. Next
> map/transform the XML message into an internal XML (= Data Model) stream
> (this is why I have to map/transform various XML format into a XML one). Use
> JAXB to map the XML towards our entities beans used by hibernate to commit
> the information into the database
>
> 2) POJO to POJO
> Transform all the incoming messages into POJO objects. Map/Transform the
> POJOs into another POJOs (= entities beans used by hibernate) representing
> our datamodel. Apparently Dozer is an interesting tool to map/transform
> object into another object but paint full to use/debug.
>
> Regards,
>
> Charles

-- 
Best regards,
 Daniel Dekany


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