[hibernate-dev] [feature request][discuss] smoother serializers integration?

Steve Ebersole steve at hibernate.org
Thu May 4 13:16:14 EDT 2017


But your psuedo code is really just the same as:

AnEntity e = find();
if ( isInitialized( e ) ) {
    serializer.serialize(e);
}

boolean isInitialized(Object e) {
    return Hibernate.isInitialized( e );
}

What I was getting at with the 6.0 + Navigavble discussion is that it would
be better to base this "isInitialized" on these Navigables instead.  A
Navigable is a polymorphic reference that might be an entity, a persistent
attribute, a "collection element", etc.


On Thu, May 4, 2017 at 11:46 AM Romain Manni-Bucau <rmannibucau at gmail.com>
wrote:

> 2017-05-04 18:42 GMT+02:00 Christian Beikov <christian.beikov at gmail.com>:
>
>> Detecting if an object is initialized should be as easy as calling "
>> Hibernate.isInitialized(object)". If you want to know whether a specic
>> attribute of an object is initialized you'd use "Hibernate.isPropertyInitialized(object,
>> attributeName)". What you want is some kind of integration that makes
>> use of these two methods, so that if they return false, a null value is
>> used when serializing objects to XML/JSON via JAXB/JSONB. Is that correct?
>>
>
> Almost, I would like one able to just disable it, this way the serializer
> doesnt need anything or knowledge of hibernate. Worse case we need to
> integrate with the serializer in a way close to the one i proposed for
> johnzon before.
>
> In pseudo code it would be:
>
> AnEntity e = find();
> Hibernate.disableLazyExceptionWithNull(e);
> serializer.serialize(e);
>
>
>> I don't know of any hook in JAXB that could be used to put that code into
>> so it works out as you'd expect it. The only other way I can think of, is
>> nulling the properties explicitly which could be done quite easily. You
>> probably gonna need just a single recursive method to do that. I don't see
>> how that method should be part of Hibernate nor how you'd expect to be able
>> to configure Hibernate so that it would do that transparently.
>>
> the switch of lazyexception to null would work wit jaxb. Otherwise you
> need some more low level integration not portable IIRC.
>
>
>> I still think the cleanest solution would be to have DTOs, which is why
>> I'd argue that such a halve solution shouldn't be part of Hibernate.
>>
>
> Think we all agree (or agreed already ;)) but created this thread cause i
> saw it often enough to be a need.
>
>
>>
>> Mit freundlichen Grüßen,
>> ------------------------------
>> *Christian Beikov*
>> Am 04.05.2017 um 18:00 schrieb Romain Manni-Bucau:
>>
>>
>>
>> 2017-05-04 17:33 GMT+02:00 Steve Ebersole <steve at hibernate.org>:
>>
>>> What exactly would this "utility one level further than existing ones"
>>> do?
>>>
>>>
>> Multiple options are possible but one is to return null instead of
>> throwing lazy exception for instance.
>>
>>
>>> And for what it is worth, IMO the new Navigable model in 6.0 will again
>>> help here.  Especially in conjunction with the Navigable visitation
>>> support.
>>>
>>
>> I'm not familiar enough but if it providers for each member a way to know
>> if it is loaded or not it can work.
>>
>>
>>>
>>> On Thu, May 4, 2017 at 10:27 AM Christian Beikov <
>>> christian.beikov at gmail.com>
>>> wrote:
>>>
>>> > Well that is again exactly what a DTO is good for. If you as developer
>>> > want the groups to be available, you add a list of groups to that
>>> > special DTO type for that use case. In your data access layer you
>>> > somehow populate that, which is normally done by using some mapper
>>> > library like MapStruct or Dozer and then JAXB/JSONB can just work with
>>> > the DTO type without any problems.
>>> >
>>> > Now if you forget to add a JOIN FETCH to your query and you end up with
>>> > N+1 queries, that's a different problem, just like the amount of
>>> > boilerplate code needed for having DTO types for every use case. That I
>>> > try to solve with Blaze-Persistence Entity Views.
>>> >
>>> > Just a quick example to make my point here. If you have a REST endpoint
>>> > /user/{id} and want to provide the list of group names along with the
>>> > user information, you'd create a UserInfoDTO.
>>> >
>>> > @EntityView(User.class)
>>> > interface UserInfoDTO {
>>> >    String getUsername();
>>> >    @Mapping("groups.name")
>>> >    List<String> getGroups();
>>> > }
>>> >
>>> > Your repository returns an object of that type and you just pass that
>>> > object through so JAXB/JSONB can do their work. The mapping information
>>> > in the DTO is applied on a "source query" i.e. only doing the work
>>> > absolutely necessary to satisfy the requested projection.
>>> >
>>> > Implementing this by hand is by no means impossible, but rather
>>> > inconvenient I'd say, which is probably why you are seeking for other
>>> > solutions.
>>> >
>>> > In the end, you can only try to create a minimal DTO that has exactly
>>> > the fields you want to be serialized or annotate your existing entities
>>> > with those "ignore" annotations and hope for the best. I don't see how
>>> > hibernate could or should help in any of the two cases.
>>> >
>>> > Mit freundlichen Grüßen,
>>> >
>>> ------------------------------------------------------------------------
>>> > *Christian Beikov*
>>> > Am 04.05.2017 um 16:59 schrieb Romain Manni-Bucau:
>>> > > Sure. If you add any conversion logic then you are clearly out of
>>> > > hibernate scope and the problem doesnt appear anymore. Here is a
>>> > > trivial example (hopefully trivial at least ;))
>>> > >
>>> > > User 1 - n Group
>>> > >
>>> > > In json we would get something like {username:...,groups:[group1,
>>> > > group2]}, no issue to know if group should be loaded or not since
>>> this
>>> > > part of the logic is in the mapper layer.
>>> > >
>>> > > So yes you can say "not my problem" but next framework will
>>> > > immediately ask "how do i know" and you likely end like all
>>> > > spring-data-rest recommandation with a specific mapping and not a
>>> > > framework solution which is the target of that thread - at least what
>>> > > I tried to explain ;).
>>> > >
>>> > > 2017-05-04 16:41 GMT+02:00 Christian Beikov
>>> > > <christian.beikov at gmail.com <mailto:christian.beikov at gmail.com>>:
>>> > >
>>> > >     I don't understand what you mean by "you put that logic in the
>>> > >     conversion", could you elaborate?
>>> > >
>>> > >
>>> > >     Mit freundlichen Grüßen,
>>> > >
>>> >
>>> ------------------------------------------------------------------------
>>> > >     *Christian Beikov*
>>> > >     Am 04.05.2017 um 16:32 schrieb Romain Manni-Bucau:
>>> > >>     Few more points:
>>> > >>
>>> > >>     1. Dto dont help at any moment - or you put that logic in the
>>> > >>     conversion and you are back to start
>>> > >>     2. Making jaxb/jsonb easy to integrate is the goal IMO. No need
>>> > >>     to integrate with them but just provide some utility one level
>>> > >>     further than existing ones
>>> > >>
>>> > >>     Le 4 mai 2017 16:13, "Steve Ebersole" <steve at hibernate.org
>>> > >>     <mailto:steve at hibernate.org>> a écrit :
>>> > >>
>>> > >>         Oops, that (3) in previous reply should have read:
>>> > >>         3. supporting each format creates a new "optional" library
>>> > >>         dependency
>>> > >>
>>> > >>         Overall, I like Christian's approach as a potential
>>> > >>         generalized approach to
>>> > >>         this.  Basically a combination of
>>> > >>
>>> > >>            1. a query used to provide the "view source values"
>>> > >>            2. some indication of how to map those "source values" to
>>> > >>         your view model
>>> > >>
>>> > >>
>>> > >>         And again, I think 6.0's improved dynamic-instantiation
>>> > >>         queries are a
>>> > >>         simple, already-built-in way to achieve that for most cases.
>>> > >>         But I am open
>>> > >>         to discussing a way to supply that combination via API if we
>>> > >>         deem that
>>> > >>         would be good - although then I'd also question how the
>>> current
>>> > >>         TupleTransformer does not meet that need.
>>> > >>
>>> > >>         On Thu, May 4, 2017 at 8:43 AM Steve Ebersole
>>> > >>         <steve at hibernate.org <mailto:steve at hibernate.org>> wrote:
>>> > >>
>>> > >>         > Were there a standard "represent something in XML-ish
>>> > >>         format" contract
>>> > >>         > portable across a number of formats (XML, JAXB, JSON, etc)
>>> > >>         then I'd be more
>>> > >>         > inclined to agree with this.  But as it is, supporting
>>> this
>>> > >>         would mean
>>> > >>         > Hibernate implementing multiple such contracts, one per
>>> > >>         format.  However,
>>> > >>         >
>>> > >>         >    1. these formats are not our core competency
>>> > >>         >    2. maintaining a complete set of these transformers
>>> > >>         across all the
>>> > >>         >    popular formats du-jour is a large undertaking
>>> > >>         >    3. I am not convinced that
>>> > >>         >
>>> > >>         > All of these increase the technical risk.
>>> > >>         >
>>> > >>         > Additionally, to properly support this we'd really need
>>> the
>>> > >>         ability to
>>> > >>         > then "map" multiple views for a given entity-graph-root.
>>> > >>         What I mean by
>>> > >>         > that, is that such DTO approaches often need multiple
>>> > >>         "views" of a given
>>> > >>         > entity, e.g. a CompanyListDTO, CompanyOverviewDTO,
>>> > >>         > CompanyDetailsGeneralDTO, etc for a Company entity.  The
>>> > >>         point of this is
>>> > >>         > that
>>> > >>         >
>>> > >>         >    1. the transformers for these are specific to each DTO
>>> > >>         type and would
>>> > >>         >    be applied per-transformation
>>> > >>         >    2. were Hibernate to "provide" this for applications
>>> > >>         >
>>> > >>         > IMO the use of queries to obtain views is logical.
>>> > >>         Populating each of
>>> > >>         > those specific DTOs (CompanyListDTO, etc) in the most
>>> > >>         efficient way is
>>> > >>         > going to require very different SQL for each DTO.  This
>>> > >>         implies some kind
>>> > >>         > of "mapping" to be able associate each DTO with query.
>>> > >>         >
>>> > >>         > Given 6.0's improved dynamic-instantiation support, I even
>>> > >>         think that is a
>>> > >>         > great solution as well *for most cases*.
>>> > >>         >
>>> > >>         > So, while my objection has a "practical impact" component,
>>> > >>         I also just
>>> > >>         > question whether Hibernate integrating with each format's
>>> > >>         "serializer" is
>>> > >>         > the proper solution.
>>> > >>         >
>>> > >>         >
>>> > >>         >
>>> > >>         > On Thu, May 4, 2017 at 5:08 AM Christian Beikov <
>>> > >>         > christian.beikov at gmail.com
>>> > >>         <mailto:christian.beikov at gmail.com>> wrote:
>>> > >>         >
>>> > >>         >> This is exactly what I am trying to do with
>>> > >>         Blaze-Persistence Entity
>>> > >>         >> Views, making DTOs sexy and efficient :)
>>> > >>         >>
>>> > >>         >> Here a quick overview of how that looks like right now:
>>> > >>         >>
>>> > >>         >>
>>> > >>
>>> >
>>> https://persistence.blazebit.com/documentation/entity-view/manual/en_US/index.html#first-entity-view-query
>>> > >>         <
>>> >
>>> https://persistence.blazebit.com/documentation/entity-view/manual/en_US/index.html#first-entity-view-query
>>> > >
>>> > >>         >>
>>> > >>         >> One of my targets is to make it possible to do something
>>> > >>         like this
>>> > >>         >>
>>> > >>         >> entityManager.createQuery("FROM Order o",
>>> > >>         OrderDTO.class).getResultList()
>>> > >>         >>
>>> > >>         >> and get an optimal query, as well as objects with only
>>> the
>>> > >>         necessary
>>> > >>         >> contents.
>>> > >>         >>
>>> > >>         >> Maybe we can collaborate on that somehow?
>>> > >>         >>
>>> > >>         >>
>>> > >>         >> Mit freundlichen Grüßen,
>>> > >>         >>
>>> > >>
>>> >
>>> ------------------------------------------------------------------------
>>> > >>         >> *Christian Beikov*
>>> > >>         >> Am 04.05.2017 um 10:20 schrieb Emmanuel Bernard:
>>> > >>         >> > Following up a bit on my previous email.
>>> > >>         >> >
>>> > >>         >> > While a core integration might be best I think, if
>>> there
>>> > >>         are too much
>>> > >>         >> > reluctance, we can start with a dedicated hibernate-dto
>>> > >>         or whatever
>>> > >>         >> > module or even separate project that makes life easier
>>> > >>         for these "pass
>>> > >>         >> > through" use cases. This could be in the form of a
>>> > >>         wrapper API of sort
>>> > >>         >> > and hence not affect existing Hibernate ORM APIs.
>>> > >>         >> >
>>> > >>         >> > Note that the ResultTransformer approach feels like it
>>> > >>         goes a long way
>>> > >>         >> > towards fixing the problem but as demonstrated in
>>> Vlad's
>>> > >>         article
>>> > >>         >> >
>>> > >>         >>
>>> > >>
>>> >
>>> https://vladmihalcea.com/2017/04/03/why-you-should-use-the-hibernate-resulttransformer-to-customize-result-set-mappings/
>>> > >>         <
>>> >
>>> https://vladmihalcea.com/2017/04/03/why-you-should-use-the-hibernate-resulttransformer-to-customize-result-set-mappings/
>>> > >
>>> > >>         >> > it still requires quite a bit of code and a special DTO
>>> > >>         constructor
>>> > >>         >> > object. That's what we need to get rid of I think.
>>> > >>         >> >
>>> > >>         >> > Emmanuel
>>> > >>         >> >
>>> > >>         >> > On Thu 17-05-04 10:04, Emmanuel Bernard wrote:
>>> > >>         >> >> I was very much in the Vlad, Steve, Christian camp
>>> > >>         until relatively
>>> > >>         >> >> recently. One of my main concern being that replacing
>>> a
>>> > >>         proxy by null
>>> > >>         >> >> was really sending the wrong message. So I was against
>>> > >>         having Hibernate
>>> > >>         >> >> ORM facilitate such a transformation.
>>> > >>         >> >>
>>> > >>         >> >> I am changing my mind because I am realizing that a
>>> lot
>>> > >>         of applications
>>> > >>         >> >> are less complex that my perceived median. A lot of
>>> > >>         apps really just
>>> > >>         >> >> want data to be fetched out and then passed to jackson
>>> > >>         (implicitly) and
>>> > >>         >> >> pushed out as a REST response in JSON or some other
>>> > >>         serialization
>>> > >>         >> >> protocol.
>>> > >>         >> >>
>>> > >>         >> >> So while we could try and keep the stance that such a
>>> > >>         solution should
>>> > >>         >> >> remain out of scope of Hibernate ORM core, we should
>>> > >>         have a very smooth
>>> > >>         >> >> integration with something like MapStruct to create
>>> > >>         such bounded DTO on
>>> > >>         >> >> the fly. Ideally with as close to zero code as
>>> possible
>>> > >>         from the user
>>> > >>         >> >> point of view.
>>> > >>         >> >> I can't really describe how that could look like
>>> > >>         because I am not
>>> > >>         >> >> familiar enough with MapStruct but I think it should
>>> > >>         have the following
>>> > >>         >> >> characteristics:
>>> > >>         >> >>
>>> > >>         >> >> 1. do an implicit binding between the mapped object
>>> > >>         graph and a
>>> > >>         >> detached
>>> > >>         >> >>    object graph with a 1-1 mapping of type and
>>> > >>         replacing lazy objects
>>> > >>         >> and
>>> > >>         >> >>    collections with null. That's the smoothest
>>> approach
>>> > >>         and the most
>>> > >>         >> >>    common use case but also the one where an
>>> > >>         inexperienced person could
>>> > >>         >> >>    shoot at someone else's foot
>>> > >>         >> >> 2. do a binding between the mapped object graph and a
>>> > >>         detached version
>>> > >>         >> of
>>> > >>         >> >>    that object graph with a 1-1 mapping of type, but
>>> > >>         declaratively
>>> > >>         >> >>    expressing the boundaries for the detached version.
>>> > >>         This enforces a
>>> > >>         >> >>    clear thinking of the boundaries and will load lazy
>>> > >>         data in case the
>>> > >>         >> >>    object graph loaded is missing a bit. I like the
>>> > >>         idea on principle
>>> > >>         >> but
>>> > >>         >> >>    I think it overlaps a lot with the fetch graph.
>>> > >>         >> >> 3. offer a full integration between MapStruct and
>>> > >>         Hibernate ORM by
>>> > >>         >> >>    letting people express a full fledge MapStruct
>>> > >>         transformation
>>> > >>         >> between
>>> > >>         >> >>    the managed object graph and a different target
>>> > >>         structure
>>> > >>         >> >>
>>> > >>         >> >> I favored MapStruct over Dozer because we know the
>>> > >>         MapStruct lead
>>> > >>         >> quite well ;)
>>> > >>         >> >>
>>> > >>         >> >> Note however that the MapStruct approach requires an
>>> > >>         explicit object
>>> > >>         >> >> copy, it feels a bit sad to have to double memory
>>> > >>         consumption. But that
>>> > >>         >> >> might be a good enough approach and bypassing the
>>> > >>         managed object
>>> > >>         >> >> creation leads to questions around the Persistence
>>> > >>         Context contract
>>> > >>         >> >> where loading an object supposedly means it will be in
>>> > >>         the PC.
>>> > >>         >> >> Maybe a constructor like query syntax allowing to
>>> > >>         reference a MapStruct
>>> > >>         >> >> conversion logic might work?
>>> > >>         >> >>
>>> > >>         >> >>     select mapStruct('order-and-items', o) from Order
>>> o
>>> > >>         left join
>>> > >>         >> fetch o.items
>>> > >>         >> >>
>>> > >>         >> >> Emmanuel
>>> > >>         >> >>
>>> > >>         >> >>
>>> > >>         >> >> On Wed 17-04-19 14:29, Vlad Mihalcea wrote:
>>> > >>         >> >>> Hi,
>>> > >>         >> >>>
>>> > >>         >> >>> Although I keep on seeing this request from time to
>>> > >>         time, I still
>>> > >>         >> think
>>> > >>         >> >>> it's more like a Code Smell.
>>> > >>         >> >>> Entities are useful for when you plan to modify them.
>>> > >>         Otherwise, a DTO
>>> > >>         >> >>> projection is much more efficient, and you don't
>>> > >>         suffer from
>>> > >>         >> >>> LazyInitializationException.
>>> > >>         >> >>>
>>> > >>         >> >>> With the ResultTransformer, you can even build graphs
>>> > >>         of entities, as
>>> > >>         >> >>> explained in this article;
>>> > >>         >> >>>
>>> > >>         >> >>>
>>> > >>         >>
>>> > >>
>>> >
>>> https://vladmihalcea.com/2017/04/03/why-you-should-use-the-hibernate-resulttransformer-to-customize-result-set-mappings/
>>> > >>         <
>>> >
>>> https://vladmihalcea.com/2017/04/03/why-you-should-use-the-hibernate-resulttransformer-to-customize-result-set-mappings/
>>> > >
>>> > >>         >> >>>
>>> > >>         >> >>> Due to how Hibernate Proxies are handled, without
>>> > Bytecode
>>> > >>         >> Enhancement,
>>> > >>         >> >>> it's difficult to replace a Proxy with null after the
>>> > >>         Session is
>>> > >>         >> closed. If
>>> > >>         >> >>> we implemented this, we'd have to take into
>>> > >>         consideration both
>>> > >>         >> Javassist
>>> > >>         >> >>> and ByteBuddy as well as ByteCode Enhancements.
>>> > >>         >> >>>
>>> > >>         >> >>> all in all, the implementation effort might not
>>> > >>         justify the benefit,
>>> > >>         >> and
>>> > >>         >> >>> I'm skeptical of offering a feature that does not
>>> > >>         encourage data
>>> > >>         >> access
>>> > >>         >> >>> Best Practices.
>>> > >>         >> >>>
>>> > >>         >> >>> Vlad
>>> > >>         >> >>>
>>> > >>         >> >>> On Wed, Apr 19, 2017 at 2:18 PM, Christian Beikov <
>>> > >>         >> >>> christian.beikov at gmail.com
>>> > >>         <mailto:christian.beikov at gmail.com>> wrote:
>>> > >>         >> >>>
>>> > >>         >> >>>> Hey Romain,
>>> > >>         >> >>>>
>>> > >>         >> >>>> I don't think it is a good idea to expose entities
>>> > >>         directly if you
>>> > >>         >> >>>> really need a subset of the data.
>>> > >>         >> >>>> Reasons for that thinking are that it gets hard to
>>> > >>         define what needs
>>> > >>         >> to
>>> > >>         >> >>>> be fetched or is safe to be used for a particular
>>> use
>>> > >>         case. Obviously
>>> > >>         >> >>>> serialization is like a follow-up problem.
>>> > >>         >> >>>> I see 2 possible solutions to the problem and both
>>> > >>         boil down to the
>>> > >>         >> use
>>> > >>         >> >>>> of DTOs.
>>> > >>         >> >>>>
>>> > >>         >> >>>>   1. Use an object mapper(e.g. Dozer) that maps
>>> > >>         entity object graphs
>>> > >>         >> to
>>> > >>         >> >>>>      custom DTO types.
>>> > >>         >> >>>>   2. Use specialized DTOs in queries.
>>> > >>         >> >>>>
>>> > >>         >> >>>>
>>> > >>         >> >>>> Implementing 1. does not help you with lazy loading
>>> > >>         issues and 2.
>>> > >>         >> might
>>> > >>         >> >>>> require very intrusive changes in queries which is
>>> > >>         why I implemented
>>> > >>         >> >>>> Blaze-Persistence Entity Views
>>> > >>         >> >>>>
>>> > >>         <
>>> https://github.com/beikov/blaze-persistence#entity-view-usage
>>> > >>         <
>>> https://github.com/beikov/blaze-persistence#entity-view-usage
>>> > >>.
>>> > >>         >> >>>> This is a library that allows you to define DTOs
>>> with
>>> > >>         mappings to the
>>> > >>         >> >>>> entity. In a query you can define that you want
>>> > >>         results to be
>>> > >>         >> >>>> "materialized" as instances of the DTO type.
>>> > >>         >> >>>> This reduces the pain induced by properly
>>> separating the
>>> > >>         >> "presentation
>>> > >>         >> >>>> model" from the "persistence model" and at the same
>>> > >>         time will improve
>>> > >>         >> >>>> the performance by utilizing the mapping
>>> information.
>>> > >>         >> >>>> I don't want to advertise too much, just wanted to
>>> > >>         say that I had the
>>> > >>         >> >>>> same issues over and over which is why I started
>>> that
>>> > >>         project.
>>> > >>         >> >>>>
>>> > >>         >> >>>> Mit freundlichen Grüßen,
>>> > >>         >> >>>>
>>> > >>         >>
>>> > >>
>>> >
>>> ------------------------------------------------------------------------
>>> > >>         >> >>>> *Christian Beikov*
>>> > >>         >> >>>> Am 19.04.2017 um 10:51 schrieb Romain Manni-Bucau:
>>> > >>         >> >>>>> Hi guys,
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> Short sumarry: Wonder if hibernate could get a
>>> > >>         feature to kind of
>>> > >>         >> either
>>> > >>         >> >>>>> unproxy or freeze the entities once leaving the
>>> > >>         managed context to
>>> > >>         >> avoid
>>> > >>         >> >>>>> uncontrolled lazy loading on one side and
>>> > >>         serialization issues on
>>> > >>         >> another
>>> > >>         >> >>>>> side.
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> Use case example: a common example is a REST
>>> service
>>> > >>         exposing
>>> > >>         >> directly
>>> > >>         >> >>>>> hibernate entities (which is more and more common
>>> > >>         with microservice
>>> > >>         >> >>>>> "movement").
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> Objective: the goal is to not need any step - or
>>> > >>         reduce them a lot -
>>> > >>         >> >>>>> between the hibernate interaction and a potential
>>> > >>         serialization to
>>> > >>         >> avoid
>>> > >>         >> >>>>> issues with lazy loading and unexpected loading.
>>> > >>         Today it requires
>>> > >>         >> some
>>> > >>         >> >>>>> custom and hibernate specific logic in the
>>> > >>         serializer which kind of
>>> > >>         >> >>>> breaks
>>> > >>         >> >>>>> the transversality of the two concerns
>>> > >>         (serialization and object
>>> > >>         >> >>>>> management/loading).
>>> > >>         >> >>>>>
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> Implementation options I see:
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> 1. a callback requesting if the lazy relationship
>>> > >>         should be fetched,
>>> > >>         >> >>>>> something like
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> public interface GraphVisitor {
>>> > >>         >> >>>>>       boolean shouldLoad(Object rootEntity,
>>> Property
>>> > >>         property);
>>> > >>         >> >>>>> }
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> 2. An utility to remove any proxy potentially
>>> > >>         throwing an exception
>>> > >>         >> and
>>> > >>         >> >>>>> replacing the value by null or an empty collection,
>>> > >>         something like
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> MyEntity e = Hibernate.deepUnproxy(entity);
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> 3. A switch of the proxy implementation, this is
>>> > >>         close to 2 but
>>> > >>         >> wouldn't
>>> > >>         >> >>>>> require a call to any utility, just a configuration
>>> > >>         in the
>>> > >>         >> persistence
>>> > >>         >> >>>> unit.
>>> > >>         >> >>>>> Side note: of course all 3 options can be mixed to
>>> > >>         create a single
>>> > >>         >> >>>> solution
>>> > >>         >> >>>>> like having 3 implemented based on 1 for instance.
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> Configuration proposal: this would be activated
>>> > >>         through a property
>>> > >>         >> in the
>>> > >>         >> >>>>> persistence unit (this shouldn't be only global
>>> IMHO
>>> > >>         cause
>>> > >>         >> otherwise you
>>> > >>         >> >>>>> can't mix 2 kind of units, like one for JSF and one
>>> > >>         for JAX-RS to be
>>> > >>         >> >>>>> concrete). This should also be activable as a query
>>> > >>         hint i think -
>>> > >>         >> but
>>> > >>         >> >>>> more
>>> > >>         >> >>>>> a nice to have.
>>> > >>         >> >>>>>
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> What this feature wouldn't be responsible for:
>>> > >>         cycles. If
>>> > >>         >> relationships
>>> > >>         >> >>>> are
>>> > >>         >> >>>>> bidirectional then the unproxied entity would still
>>> > >>         "loop" if you
>>> > >>         >> browse
>>> > >>         >> >>>>> the object graph - this responsability would stay
>>> in
>>> > >>         the consumer
>>> > >>         >> since
>>> > >>         >> >>>> it
>>> > >>         >> >>>>> doesn't depend on hibernate directly but more on a
>>> > >>         plain object
>>> > >>         >> handling.
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> What do you think?
>>> > >>         >> >>>>>
>>> > >>         >> >>>>>
>>> > >>         >> >>>>> Romain Manni-Bucau
>>> > >>         >> >>>>> @rmannibucau <https://twitter.com/rmannibucau
>>> > >>         <https://twitter.com/rmannibucau>> |  Blog
>>> > >>         >> >>>>> <https://blog-rmannibucau.rhcloud.com
>>> > >>         <https://blog-rmannibucau.rhcloud.com>> | Old Blog
>>> > >>         >> >>>>> <http://rmannibucau.wordpress.com
>>> > >>         <http://rmannibucau.wordpress.com>> | Github <
>>> > https://github.com/
>>> > >>         >> >>>> rmannibucau> |
>>> > >>         >> >>>>> LinkedIn <https://www.linkedin.com/in/rmannibucau
>>> > >>         <https://www.linkedin.com/in/rmannibucau>> | JavaEE Factory
>>> > >>         >> >>>>> <https://javaeefactory-rmannibucau.rhcloud.com
>>> > >>         <https://javaeefactory-rmannibucau.rhcloud.com>>
>>> > >>         >> >>>>> _______________________________________________
>>> > >>         >> >>>>> hibernate-dev mailing list
>>> > >>         >> >>>>> hibernate-dev at lists.jboss.org
>>> > >>         <mailto:hibernate-dev at lists.jboss.org>
>>> > >>         >> >>>>>
>>> > >>         https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>> > >>         <https://lists.jboss.org/mailman/listinfo/hibernate-dev>
>>> > >>         >> >>>> _______________________________________________
>>> > >>         >> >>>> hibernate-dev mailing list
>>> > >>         >> >>>> hibernate-dev at lists.jboss.org
>>> > >>         <mailto:hibernate-dev at lists.jboss.org>
>>> > >>         >> >>>>
>>> > >>         https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>> > >>         <https://lists.jboss.org/mailman/listinfo/hibernate-dev>
>>> > >>         >> >>>>
>>> > >>         >> >>> _______________________________________________
>>> > >>         >> >>> hibernate-dev mailing list
>>> > >>         >> >>> hibernate-dev at lists.jboss.org
>>> > >>         <mailto:hibernate-dev at lists.jboss.org>
>>> > >>         >> >>>
>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>> > >>         <https://lists.jboss.org/mailman/listinfo/hibernate-dev>
>>> > >>         >> >> _______________________________________________
>>> > >>         >> >> hibernate-dev mailing list
>>> > >>         >> >> hibernate-dev at lists.jboss.org
>>> > >>         <mailto:hibernate-dev at lists.jboss.org>
>>> > >>         >> >>
>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>> > >>         <https://lists.jboss.org/mailman/listinfo/hibernate-dev>
>>> > >>         >> > _______________________________________________
>>> > >>         >> > hibernate-dev mailing list
>>> > >>         >> > hibernate-dev at lists.jboss.org
>>> > >>         <mailto:hibernate-dev at lists.jboss.org>
>>> > >>         >> > https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>> > >>         <https://lists.jboss.org/mailman/listinfo/hibernate-dev>
>>> > >>         >>
>>> > >>         >> _______________________________________________
>>> > >>         >> hibernate-dev mailing list
>>> > >>         >> hibernate-dev at lists.jboss.org
>>> > >>         <mailto:hibernate-dev at lists.jboss.org>
>>> > >>         >> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>> > >>         <https://lists.jboss.org/mailman/listinfo/hibernate-dev>
>>> > >>         >>
>>> > >>         >
>>> > >>         _______________________________________________
>>> > >>         hibernate-dev mailing list
>>> > >>         hibernate-dev at lists.jboss.org
>>> > >>         <mailto:hibernate-dev at lists.jboss.org>
>>> > >>         https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>> > >>         <https://lists.jboss.org/mailman/listinfo/hibernate-dev>
>>> > >>
>>> > >
>>> > >
>>> >
>>> > _______________________________________________
>>> > hibernate-dev mailing list
>>> > hibernate-dev at lists.jboss.org
>>> > https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>> _______________________________________________
>>> hibernate-dev mailing list
>>> hibernate-dev at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>>
>>
>>
>>


More information about the hibernate-dev mailing list