[hibernate-dev] HHH-9440 Support for Java 8: parameter names

[Steve Ebersole]

Commented on the Jira.

I am confused how you are "mind mapping" PreparedStatement parameters and
entity construction into the same conversation.  We are not instantiating
entities based on PreparedStatement parameters....

On Fri, Mar 18, 2016 at 2:32 AM Lovro Pandzic <lovro.pandzic at gmail.com>
wrote:

> Hello,
>
> I'd like to discuss issue HHH-9440.
>
> Basic idea behind this issue is that we try to and eliminate the
> requirement for no arg constructor on entities or at least weaken that
> requirement to specific cases.
> Construction from both the user code and the hibernate itself would go
> through user specified constructors.
> This would enable use cases like enforcing invariants in constructors,
> immutable entities and in the long run, maybe even support for value types
> coming in Java 10 that, at least for now, we know will be immutable and
> won't have a no arg constructor.
>
> By using parameter names and Java 8 API you can, for instance, map those
> parameter names to fields to find out column mappings and other information
> required for mapping arguments to parameters.
>
> A similar approach like this is used by jackson-databind with the
> jackson-module-parameter-names (this will soon be integrated into the
> jackson-databind itself). Another example, Spring also uses parameter names
> to map bean names to parameters in constructors.
>
> There are border cases like the one Steve mentioned in the issue:
>
> > How would you see lazy loading working then?
> >
>
> >From my perspective, there are 2 approaches here:
> - use a library like Objenesis that enables you to construct classes
> without using the constructor
> - document that all entities that are to be proxied must have a no arg
> constructor
>
> What do you guys think?
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