@Transient : disable persisting data

By default all the instance fields of your class persist in database. There are situation, where you don’t want to persist some fields. You can do this by using @Transient annotation.

package myFirstHibernate;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Transient;

@Entity
public class Employee {
  @Id
  @Column(name="emp_id")
  private int id;
  private String firstName;
  private String lastName;
  private String designation;
  private int age;
  private double salary;
  
  @Transient
  private String hobbies;
    
  public String getHobbies() {
    return hobbies;
  }

  public void setHobbies(String hobbies) {
    this.hobbies = hobbies;
  }

  public int getId() {
    return id;
  }
  
  public void setId(int id) {
    this.id = id;
  }
  
  public String getFirstName() {
    return firstName;
  }
  
  public void setFirstName(String firstName) {
    this.firstName = firstName;
  }
  
  public String getLastName() {
    return lastName;
  }
  
  public void setLastName(String lastName) {
    this.lastName = lastName;
  }
  
  public String getDesignation() {
    return designation;
  }
  
  public void setDesignation(String designation) {
    this.designation = designation;
  }
  
  public int getAge() {
    return age;
  }
  
  public void setAge(int age) {
    this.age = age;
  }
  
  public double getSalary() {
    return salary;
  }
  
  public void setSalary(double salary) {
    this.salary = salary;
  }
  
}

hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>

  <session-factory>
  
    <!--  Database Connection settings -->
    <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="connection.url">jdbc:mysql://localhost/sample</property>
    <property name="connection.username">root</property>
    <property name="connection.password">tiger</property>
    
    <!-- Enable the logging of all the generated SQL statements to the console -->
    <property name="show_sql">true</property>
    
    <!-- Format the generated SQL statement to make it more readable, -->
    <property name="format_sql">false</property>
    
    <!-- Hibernate will put comments inside all generated SQL statements to hint what’s the generated SQL trying to do -->
    <property name="use_sql_comments">false</property>
    
    <!-- This property makes Hibernate generate the appropriate SQL for the chosen database. -->
    <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
    
    <!-- Drop and re-create the database schema on startup -->
    <property name="hbm2ddl.auto">create</property>
    
    <!-- mappings for annotated classes -->
    <mapping class="myFirstHibernate.Employee" />
    
  </session-factory>
  
</hibernate-configuration>

TestEmployee.java

package myFirstHibernate;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;


public class TestEmployee {
  
  /* Step 1: Create session factory */
  private static SessionFactory getSessionFactory() {
    Configuration configuration = new Configuration().configure();
    StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().
    applySettings(configuration.getProperties());
    SessionFactory factory = configuration.buildSessionFactory(builder.build());
        return factory;
    }
  
  public static void main(String args[]){
    Employee emp1 = new Employee();
    emp1.setAge(26);
    emp1.setDesignation("Senior Software Developer");
    emp1.setFirstName("Hari Krishna");
    emp1.setId(1);
    emp1.setLastName("Gurram");
    emp1.setSalary(80000);
    emp1.setHobbies("Writing blog");
    
    SessionFactory sessionFactory = getSessionFactory();
    Session session = sessionFactory.openSession();
    session.beginTransaction();
    session.save(emp1);
    session.getTransaction().commit();
    session.close();   
  }
}

Run “TestEmployee” class, you will get output like below.

Hibernate: drop table if exists Employee
Hibernate: create table Employee (emp_id integer not null, age integer not null, designation varchar(255), firstName varchar(255), lastName varchar(255), salary double precision not null, primary key (emp_id))
Dec 20, 2014 12:00:06 AM org.hibernate.tool.hbm2ddl.SchemaExport execute
INFO: HHH000230: Schema export complete
Hibernate: insert into Employee (age, designation, firstName, lastName, salary, emp_id) values (?, ?, ?, ?, ?, ?)

As you observe the output, the field hobbies is not persisted into database.

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