How do I order the Criteria query result set?

By Wayan in Hibernate 0 Comment

In this demo you’ll see how to order the result set of out Criteria query. It can be done by adding the org.hibernate.criterion.Order into the Criteria object, and we can either order the result in ascending or descending order.

package org.kodejava.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.Session;
import org.hibernate.HibernateException;
import org.hibernate.Criteria;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Order;
import org.kodejava.hibernate.model.Track;

import java.util.List;

public class CriteriaOrderDemo {
    public static Session getSession() throws HibernateException {
        String cfg = "hibernate.cfg.xml";
        SessionFactory sessionFactory = new Configuration().configure(cfg)
                .buildSessionFactory();
        return sessionFactory.openSession();
    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        try (Session session = getSession()) {
            Criteria criteria = session.createCriteria(Track.class)
                    .addOrder(Order.asc("title"))
                    .setFirstResult(0)
                    .setMaxResults(10);

            List<Track> tracks = criteria.list();
            for (Track track : tracks) {
                System.out.println("Track = " + track.getTitle());
            }
        }
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.9.Final</version>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.0.33</version>
    </dependency>
</dependencies>

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How do I add Restrictions to the Criteria object?

By Wayan in Hibernate 0 Comment

In this example you’ll learn how to add restrictions to the Criteria object. Using restriction we can narrow the result of our query. In the code below we add some restrictions such as Restrictions.eq(), Restrictions.like() and Restrictions.isNotNull().

In Hibernate framework you’ll find a lot of class the use a method chaining. As in the example below you can see that we actually can add an endless restrictions by calling the add() method.

package org.kodejava.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.Session;
import org.hibernate.HibernateException;
import org.hibernate.Criteria;
import org.hibernate.criterion.Restrictions;
import org.hibernate.cfg.Configuration;
import org.kodejava.hibernate.model.Track;

import java.util.List;

public class RestrictionsDemo {
    public static Session getSession() throws HibernateException {
        String cfg = "hibernate.cfg.xml";
        SessionFactory sessionFactory = new Configuration().configure(cfg)
                .buildSessionFactory();
        return sessionFactory.openSession();
    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        try (Session session = getSession()) {
            Criteria criteria = session.createCriteria(Track.class)
                    .createAlias("artist", "artist")
                    .createAlias("genre", "genre")
                    .add(Restrictions.eq("title", "Ob-La-Di, Ob-La-Da"))
                    .add(Restrictions.like("artist.name", "%Beatles%"))
                    .add(Restrictions.isNotNull("genre.name"));

            List<Track> tracks = criteria.list();
            for (Track track : tracks) {
                System.out.println("Track = " + track.getTitle() +
                        "; Artist = " + track.getArtist().getName() +
                        "; Genre = " + track.getGenre().getName());
            }
        }
    }
}

Here are some other restrictions that can also be used to narrow our Criteria query result, for a complete restrictions you can see the Restrictions class documentation.

  • Restrictions.ne("title", "Twist and Shout") – Apply a “not equal” constraint to the named property.
  • Restrictions.ilike("title", "Twist%") – A case-insensitive “like”.
  • Restrictions.isNull("title") – Apply an “is null” constraint to the named property.
  • Restrictions.gt("duration", new Integer(200)) – Apply a “greater than” constraint to the named property.
  • Restrictions.between("duration", new Integer(100), new Integer(200)) – Apply a “between” constraint to the named property
  • Restrictions.or(criterionA, criterionB) – Return the disjunction of two expressions.
  • Restrictions.disjuction() – Group expressions together in a single disjunction.

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.9.Final</version>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.0.33</version>
    </dependency>
</dependencies>

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How do I create a pagination using Criteria?

By Wayan in Hibernate 0 Comment

To create a pagination or limit the result set returned by the Criteria query we can use the setFirstResult() and setMaxResults() method. The setFirstResult() method defines the first row to start with and the setMaxResults() method defines the maximum number of records to read. Let’s see the demo below.

package org.kodejava.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.Session;
import org.hibernate.HibernateException;
import org.hibernate.Criteria;
import org.hibernate.cfg.Configuration;
import org.kodejava.hibernate.model.Track;

import java.util.List;

public class CriteriaPagingDemo {
    public static Session getSession() throws HibernateException {
        String cfg = "hibernate.cfg.xml";
        SessionFactory sessionFactory = new Configuration().configure(cfg)
                .buildSessionFactory();
        return sessionFactory.openSession();
    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        try (Session session = getSession()) {
            Criteria criteria = session.createCriteria(Track.class);

            // Set the first record index to read from the result set.
            criteria.setFirstResult(0);
            // Set the maximum number of records to read
            criteria.setMaxResults(10);

            List<Track> tracks = criteria.list();
            for (Track track : tracks) {
                System.out.println("Track = " + track.getTitle());
            }
        }
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.9.Final</version>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.0.33</version>
    </dependency>
</dependencies>

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How do I create a Criteria object?

By Wayan in Hibernate 0 Comment

This example show you how to create an instance of Hibernate Criteria class. To create a Criteria we call the factory method of the Session object and pass the persistence class as parameter. To execute the Criteria query we simply call the list() method.

package org.kodejava.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.Session;
import org.hibernate.HibernateException;
import org.hibernate.Criteria;
import org.hibernate.cfg.Configuration;
import org.kodejava.hibernate.model.Track;

import java.util.List;

public class CreateCriteriaDemo {
    public static Session getSession() throws HibernateException {
        String cfg = "hibernate.cfg.xml";
        SessionFactory sessionFactory = new Configuration().configure(cfg)
                .buildSessionFactory();
        return sessionFactory.openSession();
    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        try (Session session = getSession()) {
            // Create a new Criteria to query for a collection of Tracks.
            // To create an instance of Criteria we call a createCriteria()
            // factory method of the Session object.
            Criteria criteria = session.createCriteria(Track.class);

            // Call the list() method to retrieve a collections of Tracks
            // from the database.
            List<Track> tracks = criteria.list();

            for (Track track : tracks) {
                System.out.println("Title     = " + track.getTitle());
                System.out.println("Artist    = " + track.getArtist().getName());
                System.out.println("Genre     = " + track.getGenre().getName());
                System.out.println("Record    = " + track.getRecord().getTitle());
                System.out.println("Label     = " + track.getRecord().getLabel().getName());
                System.out.println("-----------------------------------");
            }
        }
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.9.Final</version>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.0.33</version>
    </dependency>
</dependencies>

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How do I limit Hibernate query result?

By Wayan in Hibernate 0 Comment

In the example below you’ll see how to limit the number of records returned by hibernate queries. Limiting the query result is usually use for creating pagination, where we can navigate from page to page of data in our application but only a few of them are read from the database.

In hibernate Query object we need to specify the first result and max results by calling the setFirstResult() and setMaxResults() methods to limit the query results.

package org.kodejava.hibernate.service;

import org.hibernate.Session;
import org.hibernate.query.Query;
import org.kodejava.hibernate.SessionFactoryHelper;
import org.kodejava.hibernate.model.Label;

import java.util.List;

public class LabelService {
    public List<Label> getLabels(int pageNumber, int pageSize) {
        Session session =
                SessionFactoryHelper.getSessionFactory().getCurrentSession();
        session.beginTransaction();

        Query<Label> query = session.createQuery("from Label", Label.class);

        // Set the first record position and the max number of record to be
        // read. The setFirstResult() tell hibernate from which row the data
        // should be read. In the example if we have pages of 10 records,
        // passing the page number 2 will read 10 records from the 20th row
        // in the selected records.
        query.setFirstResult((pageNumber - 1) * pageSize);
        query.setMaxResults(pageSize);

        List<Label> labels = query.list();
        session.getTransaction().commit();
        return labels;
    }
}

package org.kodejava.hibernate;

import org.kodejava.hibernate.model.Label;
import org.kodejava.hibernate.service.LabelService;

import java.util.List;

public class LimitDemo {
    public static void main(String[] args) {
        LabelService service = new LabelService();

        List<Label> labels = service.getLabels(1, 10);
        for (Label label : labels) {
            System.out.println("Label = " + label);
        }
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.9.Final</version>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.0.33</version>
    </dependency>
</dependencies>

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