[hibernate-dev] [HV/HSEARCH] Free form

[Emmanuel Bernard]

Your prototype is very Hibernate Search tainted. I wonder how or whether we want it reusable across Hibernate Validator, Search and possibly more.

Have you captured somewhere the discussion about the new document builder so I could get a better grip of what’s at bay?
Would this reverse of logic also be embraced by Hibernate Validator? There are runtime decisions done in HV during traversal that made me doubt that it would be as pertinent.



> On 30 Jan 2017, at 11:21, Yoann Rodiere <yrodiere at redhat.com> wrote:
> 
> Hi,
> 
> Did the same this week-end, and adapted your work to match the bigger picture of what we discussed on Friday.
> Basically the "StructureTraverser" is now called "ValueProcessor", because it's not responsible for exposing the internals of a structure anymore, but only to process a structure according to previously defined metadata, passing the output to the "DocumentContext". I think it's the second option you suggested. It makes sense in my opinion, since metadata will be defined differently for different source types (POJO, JSON, ...).
> This design allows in particular what Sanne suggested: when bootstrapping, we can build some kind of "walker" (a composition of "ValueProcessors") from the metadata, and avoid metadata lookup at runtime.
> 
> The snippet is there: https://gist.github.com/yrodiere/9ff8fe8a8c7f59c1a051b36db20fbd4d <https://gist.github.com/yrodiere/9ff8fe8a8c7f59c1a051b36db20fbd4d>
> 
> I'm sure it'll have to be refined to address additional constraints, but in its current state it seems to address all of our requirements.
> 
> Yoann Rodière <yrodiere at redhat.com <mailto:yrodiere at redhat.com>>
> Software Engineer
> Red Hat / Hibernate NoORM Team
> 
> On 27 January 2017 at 18:23, Emmanuel Bernard <emmanuel at hibernate.org <mailto:emmanuel at hibernate.org>> wrote:
> I took the flight home to play with free form and specifically how we would retrieve data from the free form structure.
> By free-form I mean non POJO but they will have schema (not expressed here).
> 
> https://github.com/emmanuelbernard/hibernate-search/commit/0bd3fbab137bdad81bfa5b9934063792a050f537 <https://github.com/emmanuelbernard/hibernate-search/commit/0bd3fbab137bdad81bfa5b9934063792a050f537>
> 
> And in particular
> https://github.com/emmanuelbernard/hibernate-search/blob/freeform/freeform/src/main/java/org/hibernate/freeform/StructureTraverser.java <https://github.com/emmanuelbernard/hibernate-search/blob/freeform/freeform/src/main/java/org/hibernate/freeform/StructureTraverser.java>
> https://github.com/emmanuelbernard/hibernate-search/blob/freeform/freeform/src/main/java/org/hibernate/freeform/pojo/impl/PojoStructureTraverser.java <https://github.com/emmanuelbernard/hibernate-search/blob/freeform/freeform/src/main/java/org/hibernate/freeform/pojo/impl/PojoStructureTraverser.java>
> 
> It probably does not compile, I could not make the build work.
> 
> I figured it was important to dump this raw thinking because it will influence and will be influenced by the redesign of the DocumentBuilder of Hibernate Search.
> 
> There are several options for traversing a free form structure
> - expose  the traversing API as a holder to  navigate all properties per structure and sub structure. This is what the prototype shows. Caching needs to be accessed via a hashmap get or other lookup. Metadata and the traversing structure will be navigated in parallel
> - expose a structure that is specialized to a single property or container unwrapping aspect. The structures will be spread across and embedded in the Metadata
> 
> 
> Another angle:
> - create a traversable object per payload to carry it (sharing metadata info per type)
> - have a stateless traversable object that is provided the payload for each access
> 
> The former seems better as it does not create a traversable object per object navigated.
> The latter is better for payloads that need parsing or are better at sequential access since state could be cached.
> 
> We need to discuss that and know where DocumentBuilder is going to properly design this API.
> 
> Emmanuel
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