Hibernate: Sorting children through a onetomany + manytoone relation

Question

I have a Contact entity connected to a ContactList entity through a @OneToMany relation. Then the ContactList entity connects to the Review List entity through @ManyToOne. The ContactList entity has data related to the contact on the list. I need to sort the ContactList children from the Contact by the createdOn timestamp in Review List. I am not sure this is possible.

Contact entity

@OneToMany(mappedBy = "contact")
@OrderBy("created_on DESC") <-- This does not work.
private SortedSet<ContactList> contactLists;

ContactList entity:

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "LIST_ID")
private ReviewList reviewList;

ContactList compareTo:

@Override
public int compareTo(ContactList b) {
    if (this.getReviewList().getCreatedOn().getTime() == b.getReviewList().getCreatedOn().getTime()) {
        log.error("Two review lists have the exact same created time???");
        return 0;
    }

    return this.getReviewList().getCreatedOn().getTime() < b.getReviewList().getCreatedOn().getTime() ? -1 : 1;
}

Review List createdOn field I am trying to sort the parent by:

@Column(name="CREATED_ON", updatable=false)
private Timestamp createdOn;

I have tried it without the @OrderBy notation, and it will not compile. But everything I have tried to put in the quote fails. I have tried contactList as shown, reviewList, reviewList.createdOn, reviewList_createdOn, and a couple others that were really dumb.

It seems like Hibernate is taking the first part of the quoted string and putting it into the query directly. Whatever I put in there errors with this:

Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'contactlis0_.created_on' in 'order clause' at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_91] at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_91] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_91] at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_91] at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) ~[mysql-connector-java-5.1.44.jar:5.1.44] at com.mysql.jdbc.Util.getInstance(Util.java:408) ~[mysql-connector-java-5.1.44.jar:5.1.44] at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:943) ~[mysql-connector-java-5.1.44.jar:5.1.44]

And of course it does, since I'm trying to reference a field in another table. It needs to do some sort of JoinColumn in between.

Is there any way to do this? I could probably write a custom JPQL query to sort them how I want and pass that to the page separately, but I was trying to do this with annotation and hibernate.

Answer 1

I believe what is causing you issues is that fact that you are using a SortedSet. Regardless of how hibernate inserts values, they will be ordered according to the contract of SortedSet. Unless you have implemented Comparable on ContactList , this will be the natural ordering of ContactList. If you have implemented Comparable, then your list will sort according to that implementation. I don't think either is your desired outcome.

Try defining your collection as a Set , if you want the DB to perform the ordering.

Answer 2

My solution so far is to add a 'list_created_on' field to the ContactList object, and then update the data so that every record has the ReviewList created_on date. Then whenever I create a new ContactList in the database, I just set it to the created date of the review list. I don't really like keeping the same data in two spots, but I can't get around it.

It seems inelegant, but I could not figure out how to reference the child of a child in hibernate using annotation. And the sorting now works the way I wanted.

I will not accept this as an answer in case anyone else has a better solution.