Use the select new map syntax in HQL to fetch the results of each row in a Map. Take a look at the following question, that addresses the issue: How to fetch hibernate query result as associative array of list or hashmap. For instance, the following HQL: select new map(perm.id as pid, perm.name as pname) … Read more
The Exception is straightforward and says : Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements, so the cause is obvious here and if we take a look at the Hibernate Collection mapping documentation it clearly states that: As a requirement persistent collection-valued fields must be declared as an interface type … Read more
You can simply get these types via Maven Central using the Hypersistence Util dependency: <dependency> <groupId>io.hypersistence</groupId> <artifactId>hypersistence-utils-hibernate-55</artifactId> <version>${hibernate-types.version}</version> </dependency> If you easily map Java Enum to a PostgreSQL Enum column type using the following custom Type: public class PostgreSQLEnumType extends org.hibernate.type.EnumType { public void nullSafeSet( PreparedStatement st, Object value, int index, SharedSessionContractImplementor session) throws HibernateException, … Read more
There is no Hibernate annotation that checks uniqueness before insert/update. But there is annotation which will generate such a constraint to database if automatic database creation is used: @Table( name=”ACTIVE_BAND”, uniqueConstraints= @UniqueConstraint(columnNames={“active_band_user”, “active_band_date”}) )
The Hibernate Proxy is used to substitute an actual entity POJO (Plain Old Java Object). The Proxy class is generated at runtime and it extends the original entity class. Hibernate uses Proxy objects for entities is for to allow [lazy loading][1]. When accessing basic properties on the Proxy, it simply delegates the call to the … Read more
I think the annotation you are looking for is: public class CompanyName implements Serializable { //… @JoinColumn(name = “COMPANY_ID”, referencedColumnName = “COMPANY_ID”, insertable = false, updatable = false) private Company company; And you should be able to use similar mappings in a hbm.xml as shown here (in 23.4.2): http://docs.jboss.org/hibernate/core/3.3/reference/en/html/example-mappings.html
@Column is not the appropriate annotation. You don’t want to store a whole User or Question in a column. You want to create an association between the entities. Start by renaming Questions to Question, since an instance represents a single question, and not several ones. Then create the association: @Entity @Table(name = “UserAnswer”) public class … Read more
The exception message says: Books is not mapped [SELECT COUNT(*) FROM Books]; nested exception is org.hibernate.hql.ast.QuerySyntaxException: Books is not mapped [SELECT COUNT(*) FROM Books] Books is not mapped. That is, that there is no mapped type called Books. And indeed, there isn’t. Your mapped type is called Book. It’s mapped to a table called Books, … Read more
JPA doesn’t offer any support for derived property so you’ll have to use a provider specific extension. As you mentioned, @Formula is perfect for this when using Hibernate. You can use an SQL fragment: @Formula(“PRICE*1.155”) private float finalPrice; Or even complex queries on other tables: @Formula(“(select min(o.creation_date) from Orders o where o.customer_id = id)”) private … Read more
EDIT 2017-04-29: As pointed to by some of the commenters, the JoinTable example does not need the mappedBy annotation attribute. In fact, recent versions of Hibernate refuse to start up by printing the following error: org.hibernate.AnnotationException: Associations marked as mappedBy must not define database mappings like @JoinTable or @JoinColumn Let’s pretend that you have an … Read more