![]() ![]() I know about the criteria API, but I prefer the older SQL-like style. Session session = sessionFactory.openSession() The session object doesn't implement the AutoClosable interface, so take care to close the connection correctly (even and especially if an exception is thrown): However, it can be closed, so probably it's a better idea to put it in an ApplicationScoped bean and release the SessionFactory in a method annotated by Reading and writing entities (native Hibernate style) The SessionFactory has immutable state, so I suppose you can safely use it in a static final variable without opening a memory leak. However, you can automate this with a few lines of reflection. The drawback of this approach is that you have to add each Entity individually. SessionFactory = config.buildSessionFactory(ssrb.build()) StandardServiceRegistryBuilder ssrb = new StandardServiceRegistryBuilder() addAnnotatedClass(MyBusinessClass.class) setProperty("hibernate.show_sql", "true") Private static SessionFactory sessionFactory Ĭonfiguration config = new Configuration() Instead, use Configuration#addAnnotatedClass(): This method requires an *.hbm file for each and every entity. prefix to the property name.ĭon't add the entity classes via Configuration#addClass(). The properties - such as the SQL dialect, the name of the datasource and whether to create the database from scratch each time the server is started - are set by calling Configuration#setProperty(). There's nothing worse than an administrator modifying the database configuration in production without telling the development team.īasically, you need a Configuration object. I like this version better because I can debug it. Instead, I resorted to a pure Java solution. Probably I could have moved it to the classes folder. My application wouldn't start because it didn't find the configuration file. Using embedded objects student table will be populated with the columns of the address also.Configuring an XML file is all good and well - until I uploaded my app to a server with a different folder layout. We can declare an embedded component inside an entity. Selecting a single course Course course = jdbcTemplate.queryForObject("select * from course where id=?", new Object, is recommended List courses = jdbcTemplate.query("select * from course", new BeanPropertyRowMapper(Course.class)) Note: BeanPropertyRowMappermaps all the columns to a Java Pojo Criteria Query - Build a query with a Java based API.JPQL - Query language based on Enitity names (not on table names).Src/main/resources/data.sql Query data using Populate DB with data in a Spring Boot App Setting fetch time to lazy so that the passport is only selected when it is needed class Student Passport passport Note: Add mappedBy to the non-owning side of the relationship to get a biderectional navigation orphanRemoval=true) ![]() ![]() Detached: represents entity objects that have been disconnected from the EntityManager.ĭelete dependent children, when the parent is deleted.The entity object changes its state from Managed to Removed, and is physically deleted from the database during commit. Removed: A managed entity object can also be retrieved from the database and marked for deletion, using the EntityManager’s remove() method within an active transaction.Entity objects retrieved from the database by an EntityManager are also in the Managed state. Managed: An entity object becomes Managed when it is persisted to the database via an EntityManager’s persist method.In this state the object is not yet associated with an EntityManager and has no representation in the database. New: When an entity object is initially created its state is New.Note: EntityManager is an Interface to the Persistence Context entityManager.getTransaction().begin() Įager vs and fetch type is EAGER by and ManyToMany fetch type is LAZY by deafult Entity Life CycleĮntity life cycle consists of four states: New, Managed, Removed and Detached. JPA (Java Persistence API) Cheat Sheet Transaction management with EntityManager ![]()
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