[jira] [Commented] (OLINGO-49) Create of an owning Entity creates also the inverse Entity even if it exists

["Fadhly (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OLINGO-49?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14225847#comment-14225847 ] 

Fadhly commented on OLINGO-49:
------------------------------

Hi Chandan,
Can you also provide the sample in JSON. 

Thanks.

> Create of an owning Entity creates also the inverse Entity even if it exists
> ----------------------------------------------------------------------------
>
>                 Key: OLINGO-49
>                 URL: https://issues.apache.org/jira/browse/OLINGO-49
>             Project: Olingo
>          Issue Type: Bug
>          Components: odata2-jpa
>    Affects Versions: V2 1.0.0, V2 1.1.0
>            Reporter: Georgi
>            Assignee: Chandan V.A
>            Priority: Blocker
>             Fix For: V2 1.1.0
>
>
> Consider the case when you want to add a new Entity (A) to a collection of that type of entities (List<A>) that belongs to another Entity(B).
> A bi-directional JPA relationships, to model the case would be:
> A: @ManyToOne
> @JoinColumn(name = "B_ID", referencedColumnName="B_ID")
> private B b;
> B: @OneToMany(mappedBy = "b", cascade = CascadeType.ALL, fetch=FetchType.EAGER)
> private List<A> as;
> Notice that the underlying relational model would be constrained so that B_ID in A's corresponding table is a foreign key and not null. Therefore, when inserting A rows/entities we need to make sure that B exists and provides us with a valid id.
> With that setup and constraints a create request for a new A that references an existing B entity with id 3 will send something like this:
> HTTP POST <path>/As
> "{\"aId\":0\"b\":{\"__metadata\":{\"uri\":\"Bs(3)\"}}}"
> The problem is that the inline B entry here is interpreted as new one and olingo tries to create a new B instance out of it and persist it, instead of finding the B entity and setting as value to A's property b.
> That is, after normalization with normalizeInlineEntries it becomes part of the oDataEntryProperties map that is passed to the write method with flag isCreate=true, i.e. all inside is created.
> Ultimately, during em.commit this fails with :
> javax.persistence.RollbackException: java.lang.IllegalStateException: During synchronization a new object was found through a relationship that was not marked cascade PERSIST: B@xxxx
> (The object is new because it has been created out of the existing B because nobody bothered to call persist on it we get this exception. It's kind of misleading to the real problem here)
> The client is obliged to set the referenced property 'b' or otherwise it would a) violate the underlying relational model constraints 2) there's no other way to claim to which B entity's aggregation A belongs.
> So it's up to the JpaEntity implementation to consider also this case and distinguish inline requests for new entities from references to existing ones that need not be created.
> For reference case, see: http://www.odata.org/documentation/odata-v2-documentation/operations/#24_Creating_new_Entries , the second create example with the entry and link.



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