[hibernate-dev] Attribute paths and '.' versus '#' as separator

[Steve Ebersole]

To wrap this up..

The most important part for me is being able to identify the point between
the "attribute base" and the "attribute path".  If we just use a separate
delimiter there, that's enough for me.  Since one of us has a preference
for using dots within the "attribute path" part (and its irrelevant to me),
I'll go with that.  So:

org.h.SomeEntity#nv.to.hell



On Fri, Mar 28, 2014 at 3:18 PM, Steve Ebersole <steve at hibernate.org> wrote:

> What we choose as a separator after the "pivot" is irrelevant to a degree,
> especially in terms of the compatibility concern.  I think you understood
> that, just being clear.  Meaning that calls like:
>
> sessionFactoryImplementor.getCollectionPersister( "org.h.SomeEntity.nv.to.hell"
> )
>
> will fail whether we use "org.h.SomeEntity#nv.to.hell" or "org.h.SomeEntity#nv#to#hell"
> as the role key.
>
> As for "being natural", we'll agree to disagree.  But Java has no such
> notion as attributes so arguing about what is more natural in how Java
> represents attribute paths is a bit moot imo.  Were these all *accessible
> fields*, then sure the code to access them chained would use 'dots'.  But I
> think its pretty plain to see how in the call I listed above:
>
> sessionFactoryImplementor.getCollectionPersister( "org.h.SomeEntity.nv.to.hell"
> )
>
> the use of '.' locks you into never being able to programatically
> parse/understand that String structural, which I think is just very
> limiting in many places.
>
>
>
> On Fri, Mar 28, 2014 at 1:44 PM, Emmanuel Bernard <emmanuel at hibernate.org>wrote:
>
>> No strong feeling about it.
>> It will break the OGM dialects that make use of the collection role
>> though. So we need to anticipate.
>>
>> To me . looks more like the code being used and is a natural notation
>> even beyond Java. But I get that # offers some additional info.
>> Have you considered?
>>
>>     org.h.SomeEntity#nv.to.hell
>>
>> I think that would have my preference actually.
>>
>> On 27 Mar 2014, at 23:54, Steve Ebersole <steve at hibernate.org> wrote:
>>
>> > This is a bit of a potentially insidious one.  Not the best way to start
>> > off a discussion, I know :)
>> >
>> > The premise is this... Until now Hibernate has represented attribute
>> roles
>> > using dots.  For an attribute named 'department' on the
>> com.acme.Employee
>> > entity, the role would be "com.acme.Employee.department".  In terms of
>> > embeddables, say Employee had an 'address' embedded with its own
>> attributes
>> > like 'city'.  Then, the full role for 'city' would be
>> > "com.acme.Employee.address.city".
>> >
>> > As you can start to see the dots here are completely indistinguishable
>> in
>> > terms of those which define the package/class and those which identify
>> the
>> > attribute "path".
>> >
>> > So one of the things I started playing with in 5 is to replace the
>> > separators used in attribute paths to use '#', such that
>> > "com.acme.Employee.address.city" would instead be
>> > "com.acme.Employee#address#city".  This makes the role fully parseable
>> > which is actually useful in quite a few situations.  And it REALLY
>> helps in
>> > things I have just started working on like storing metadata for
>> composites
>> > (embeddeds/embeddables) on the SessionFactory, which is the first step
>> in
>> > support for some cool new features around embeddables like discriminated
>> > inheritance support.
>> >
>> > However, there is a minor drawback.  Like all attributes, collections
>> have
>> > a role.  Unfortunately the use of '.' in their role Strings leaks into
>> the
>> > SPI in terms of locating the CollectionPersisters.
>> >
>> > So the question is whether to continue with this path of replacing the
>> use
>> > of '.' with '#' for attribute path separators.  The drawback is
>> > unfortunate.  The benefit is very nice, but I can't really say it is
>> > required atm.
>> >
>> > Votes?  Thoughts?
>> > _______________________________________________
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>> > https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>
>>
>