21 - CRUD Operations

Writing code to Create, Read, Update and Delete entities in the database.

Insert record in table.

for(int i=0; i<10; i++){

                UserDetails user = new UserDetails();

                user.setUserName("User "+i);

                session.save(user);

}

Below property should be added in hibernate xml

<property name="hbm2ddl.auto">create</property>

Fetch data from table

UserDetails user = (UserDetails) session.get(UserDetails.class, 6);

System.out.println("UserName pulled up is: "+user.getUserName());

Below property should be added in hibernate xml

<property name="hbm2ddl.auto">update</property>

Delete record from table

UserDetails user = (UserDetails) session.get(UserDetails.class, 6);

session.delete(user);

Below property should be added in hibernate xml

<property name="hbm2ddl.auto">update</property>                

Update record in table

UserDetails user = (UserDetails) session.get(UserDetails.class, 7);

user.setUserName("Updated User");

session.update(user);

Below property should be added in hibernate xml

<property name="hbm2ddl.auto">update</property>                

HibernateTest.java

package org.yash.hibernate;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.Configuration;

import org.yash.dto.UserDetails;

public class HibernateTest {

      public static void main(String args[]) {

           

            SessionFactory sessionFactory = new Configuration().configure()

                        .buildSessionFactory();

            Session session = sessionFactory.openSession();

            /* It is used to save all the objects and to define single unit of work */

            session.beginTransaction();

            /* Insert records in Table */

            /*

            for(int i=0; i<10; i++){

                  UserDetails user = new UserDetails();

                  user.setUserName("User "+i);

                  session.save(user);

            }*/

           

            /* Fetch data from Table */

            UserDetails user = (UserDetails) session.get(UserDetails.class, 7);

           

            /* To delete a record from Table*/

            //session.delete(user);

           

            /* To update a record in Table*/

            user.setUserName("Updated User");

            session.update(user);

           

            session.getTransaction().commit();

            session.close();

            System.out.println("UserName pulled up is: "+user.getUserName());

      }

}

UserDetails.java

package org.yash.dto;

import java.util.ArrayList;

import java.util.Collection;

import javax.persistence.CascadeType;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.OneToMany;

import javax.persistence.Table;

@Entity

@Table(name="USER_DETAILS")

public class UserDetails {

      /* @Id says "userId" is primary key */

      @Id @GeneratedValue (strategy=GenerationType.AUTO)

      private int userId;    

      private String userName;

      @OneToMany(cascade=CascadeType.PERSIST)

      private Collection<Vehicle> vehicle = new ArrayList<Vehicle>();

           

      public int getUserId() {

            return userId;

      }

      public void setUserId(int userId) {

            this.userId = userId;

      }

      public String getUserName() {

            return userName;

      }

      public void setUserName(String userName) {

            this.userName = userName;

      }

      public void setVehicle(Collection<Vehicle> vehicle) {

            this.vehicle = vehicle;

      }

      public Collection<Vehicle> getVehicle() {

            return vehicle;

      }

}

hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?>

<!DOCTYPE hibernate-configuration PUBLIC

        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <property name="connection.driver_class">

            org.postgresql.Driver

        </property>

        <property name="connection.url">

            jdbc:postgresql://localhost:5433/hibernatedb

        </property>

        <property name="connection.username">postgres</property>

        <property name="connection.password">admin</property>

        <!-- JDBC connection pool (use the built-in) -->

        <property name="connection.pool_size">1</property>

        <!-- SQL dialect -->

        <property name="dialect">

            org.hibernate.dialect.PostgreSQLDialect

        </property>

        <!-- Enable Hibernate's automatic session context management -->

        <property name="current_session_context_class">thread</property>

       

        <!-- Echo all executed SQL to stdout -->

        <property name="show_sql">true</property>

       

        <!-- Drop and re-create the database schema on startup -->

            <property name="hbm2ddl.auto">update</property> 

<!-- create / update -->

   

          <!-- Names the annotated entity class -->

            <mapping class="org.yash.dto.UserDetails"/>    

            <mapping class="org.yash.dto.Vehicle"/>  

            <mapping class="org.yash.dto.TwoWheeler"/>     

            <mapping class="org.yash.dto.FourWheeler"/>    

           

    </session-factory>

</hibernate-configuration>