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POHibernate cascading merge with non-persistent objects
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  1. POHibernate cascading merge with non-persistent objects
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    copied!<p>I have the following structure in my project:</p> <pre><code>public class A { @Cascade({org.hibernate.annotations.CascadeType.SAVE_UPDATE, org.hibernate.annotations.CascadeType.PERSIST, org.hibernate.annotations.CascadeType.REFRESH, org.hibernate.annotations.CascadeType.MERGE}) @OneToMany(fetch = FetchType.LAZY) @JoinColumn(name = "a_id") private List&lt;B&gt; bs; } public class B { @Cascade(org.hibernate.annotations.CascadeType.ALL) @ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY) @JoinColumn(name = "b_id") private C c; } public class C { @ManyToMany(fetch = FetchType.EAGER, targetEntity = TjenesteFraIN.class, cascade = { CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH}) @JoinTable(name = "c_d", joinColumns = @JoinColumn(name = "c_id"), inverseJoinColumns = @JoinColumn(name = "d_id")) private List&lt;D&gt; ds; } public class D { ... } </code></pre> <p>Then, a scenerio where I have a detached A-object, with a reference to a detached B-object, which in turn has a reference to a detached C-object, which has references to a couple of D-objects. (I'm using JMS, so they are really really detached). Like this:</p> <pre><code>final A a = getA(123); //load A-object from database final C c = a.getSpecialC(); c.addD(getD(1)); //get Ds from database c.addD(getD(2)); //Serialize A and send JMS-call to store the A //On the other side, deserialize A, and then call public A mergeA(final A a) { return getSession(false).merge(a); } </code></pre> <p>Now, the detached A will be merged with the database representation of the A, the same for B and C, but what will happen with the new referenced from the C to the Ds? I'm seeing in practice that it does not work, nothing is stored in the c_d connection table, but i don't understand why. Is it due to limitations in Hibernate/JPA, or am I missing something with regards to my configuration?</p> <p>Update:</p> <p>By using the debugger, I was able to an explicit getSession().merge() on the C-object, and then it's references to D got stored in the database. Still don't quite get why Hibernate cascade won't take care of this for me, but will keep digging.</p>
 

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