In case of very large resulting lists, the Java-side counting and the sublisting operations can be dangerous for the memory usage and consequently also on the performance side. Instead, I usually go with the following approach: use 2 queries, one for counting the filtered resultSet (I let the db do the count), and another one … Read more
The combination of @OneToMany(mappedBy=”…”) and @OrderColumn is not supported by Hibernate. This JIRA issue tracks a request to throw a more obvious error message when this invalid combination is used: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5390 I think that this isn’t supported mainly because it is an odd relational pattern. The annotations above indicate that the “one” side of the … Read more
The message is clear: you have a repeated column in the mapping. That means you mapped the same database column twice. And indeed, you have: @Column(nullable=false) private Long customerId; and also: @ManyToOne(optional=false) @JoinColumn(name=”customerId”,referencedColumnName=”id_customer”) private Customer customer; (and the same goes for productId/product). You shouldn’t reference other entities by their ID, but by a direct reference … Read more
Try something like: @Column(name=”POSTS_REF”) @Where(clause=”state=”PostPublished””) private List<Posts> userPosts; or @Column(name=”POSTS_REF”) @Where(clause=”PostPublished=true”) private List<Posts> userPosts; depending on the status field type on your Post entity.
Here’s a snippet of hql that we use. (Names have been changed to protect identities) String queryString = “select distinct f from Foo f inner join foo.bars as b” + ” where f.creationDate >= ? and f.creationDate < ? and b.bar = ?”; return getHibernateTemplate().find(queryString, new Object[] {startDate, endDate, bar});
According to the Hibernate Reference Documentation it should be possible to mix different inheritance mapping strategies when using Hibernate’s XML-Metadata (…) Actually, it’s not really supported, they are “cheating” using a secondary table to switch from the single table strategy in the example of the documentation. Quoting Java Persistence with Hibernate: You can map whole … Read more
Both answers from Eric Lucio and Renan helped, but their use of the ids in the association table is redundant. You have both the associated entities and their ids in the class. This is not required. You can simply map the associated entity in the association class with the @Id on the associated entity field. … Read more
Using HibernateDaoSupport/HibernateTemplate is not recommended since it unnecessarily ties your code to Spring classes. Using these classes was inevitable with older versions of Hibernate in order to integrate support of Spring-managed transactions. However, since Hibernate 3.0.1 you don’t need it any more – you can write a code against a plain Hibernate API while using … Read more
DAO is an abstraction of data persistence. Repository is an abstraction of a collection of objects. DAO would be considered closer to the database, often table-centric. Repository would be considered closer to the Domain, dealing only in Aggregate Roots. Repository could be implemented using DAO‘s, but you wouldn’t do the opposite. Also, a Repository is … Read more
While similar names, the usage is different. I. Projections.distinct(Projections.property(“id”)); this statement would be translated into SQL Statement. It will be passed to DB Engine and executed as a SQL DISTINCT. See: 17.9. Projections, aggregation and grouping so e.g. this example: List results = session.createCriteria(Cat.class) .setProjection( Projections.projectionList() .add( Projections.distinct(Projections.property(“id”)) ) ) .list(); would seems like: SELECT … Read more