Hi,
I think there is no common pattern. It solely depends on your usage
scenario. If you don't need to use a reverse side of the relationship in
your business logic, I would recommend removing that part.
Mind some of the intricacies though e.g. if you remove the parent reference
field in child and not specify in parent that this column must _not_ be
null, you can get Exception with some persistence providers:
http://stackoverflow.com/questions/12755380/jpa-persisting-a-unidirectional-one-to-many-relationship-fails-with-eclipselin
Speaking from experience, Hibernate is very "tolerant" compared to e.g.
OpenJPA or EclipseLink
Greetings,
Greg
2014-03-07 10:15 GMT+01:00 Yahoo :
> Hello Greg,
> Your solution works fine.
> With a lot of Lazy Loading and circular relations
> I have the idea to include the decision which relations should be really
> loaded
> and which should be nulled
> in the Dao.Do you know if there is already a professional solution for
> this usage?
>
>
> Am 04.03.2014 23:47, schrieb gelo1234:
>
>
> Another kind of "hack" (if you cannot modify entity sources and they are
> not external .xml files) would be setting all child objects' parent
> references to null _before_ serializing that data.
>
> Lets say you got: Author and Book entites with One-To-Many relationship.
>
> You retrieve the entities from db and _before_ URLResponse, you modify
> all Books entities with null reference to parent(Author) entity:
>
>
> List authors = hibernateDAO.getAllAuthors();
>
> // make sure hibernate session is closed and authors objects are
> _detached_
> // with full data structure -> FetchType.EAGER
>
> for (Author author: authors) {
>List books = author.getBooks();
>for (Book book: books)
> book.setAuthor(null);
> }
>
> Now you can safely call URLResponse with authors (they don't contain any
> circular references anymore).
>
> Greetings,
> Greg
>
>
>
> 2014-03-04 23:00 GMT+01:00 gelo1234 :
>
>> Hi
>>
>> Can you debug where exactly a problem with circular references exists ?
>> Is it during serialization of your data ? StringTemplate? IOUtils?
>>
>> Many serialization techniques/libs do have problems with such
>> references, be it JAXB or GSON. For JAXB you can setup @Transient
>> annotation.
>>
>> How about a quick fix, that removes one side of relationship in
>> Hibernate entities making it uni-directional instead of bi-directional e.g.
>> reverse side ?
>>
>> Greetings,
>> Greg
>>
>>
>>
>> 2014-03-04 22:29 GMT+01:00 Yahoo :
>>
>> I am using Hibernate 4.1.8-Final and cocoon 3.0.0-beta-1-SNAPSHOT.
>>> But why you ask?
>>> Am 03.03.2014 08:09, schrieb Francesco Chicchiriccò:
>>>
>>> On 03/03/2014 04:36, Yahoo wrote:
> I am using cocoon RestController to present my Hibernate Mysql data
> in pdf files.
> The Hibernate structure has cirular relationships, so when I give the
> structure to the URLResponse there are endless StringBuilder calls.Do you
> have an idea how to solve this problem.One idea would be to present the
> data in an non Hibernate bean without cicular relationships. But may be
> there is an opportunity to avoid new beans.
>
Hi,
such problems arise every time JPA (or other persistence frameworks)
entities are published (via REST in your case) without any transformation
(the DTO pattern): I am afraid there is any cleaner solution than
converting your Hibernate entities into something simpler.
BTW: which version are you using?
Regards.
>>>
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>>
>
>
