Hibernate 6: Map a property to JSON (jsonb)

Using '@JdbcTypeCode( SqlTypes.JSON )' annotation, we can persist the entity properties in JSON format.

 

Example

@JdbcTypeCode(SqlTypes.JSON)
private Map<String, Object> config;

Above snippet maps the config data to jsonb type in SQL.

 

To use this JSON mapping functionality, you need to configure the JSON library that is used for serialization/deserialization by setting the property ‘hibernate.type.json_format_mapper’. 

 

At the time of writing this post, this property can be configured with the constants jackson or jsonb.

<property name="hibernate.type.json_format_mapper">jackson</property>

Find the below working application.

 

Step 1: Create new maven project ‘hibernate-json-mapping-demo’.

 

Step 2: Update pom.xml with maven dependencies.

 

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.sample.app</groupId>
    <artifactId>hibernate-json-mapping-demo</artifactId>
    <version>1</version>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

        <java.version>15</java.version>
        <maven.compiler.source>${java.version}</maven.compiler.source>
        <maven.compiler.target>${java.version}</maven.compiler.target>

    </properties>

    <dependencies>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.4.1</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>6.1.2.Final</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.13.3</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.13.3</version>
        </dependency>


    </dependencies>
</project>

Step 3: Define entity class.

 

AppConfig.java

package com.sample.app.entity;

import java.util.Map;

import org.hibernate.annotations.JdbcTypeCode;
import org.hibernate.type.SqlTypes;

import jakarta.persistence.Entity;
import jakarta.persistence.Id;
import jakarta.persistence.Table;

@Entity
@Table(name = "app_config")
public class AppConfig {
    @Id
    private Integer id;

    @JdbcTypeCode(SqlTypes.JSON)
    private Map<String, Object> config;

    public AppConfig(Integer id, Map<String, Object> config) {
        this.id = id;
        this.config = config;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Map<String, Object> getConfig() {
        return config;
    }

    public void setConfig(Map<String, Object> config) {
        this.config = config;
    }

    @Override
    public String toString() {
        return "AppConfig [id=" + id + ", config=" + config + "]";
    }

}

Step 4: Create hibernate.cfg.xml file under src/main/resources folder.

 

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">org.postgresql.Driver</property>
        <property name="connection.url">jdbc:postgresql://127.0.0.1:5432/test</property>
        <property name="connection.username">postgres</property>
        <property name="connection.password">postgres</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">true</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>

        <property name="dialect">org.hibernate.dialect.PostgreSQLDialect</property>

        <property name="hbm2ddl.auto">update</property>
        
        <property name="hibernate.type.json_format_mapper">jackson</property>

        <!-- mappings for annotated classes -->
        <mapping class="com.sample.app.entity.AppConfig" />

    </session-factory>

</hibernate-configuration>

Step 5: Define main application class.

 

App.java

package com.sample.app;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.Metadata;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;

import com.sample.app.entity.AppConfig;

import jakarta.persistence.criteria.CriteriaBuilder;
import jakarta.persistence.criteria.CriteriaQuery;

public class App {
    private static SessionFactory sessionFactory = buildSessionFactory();

    private static <T> List<T> loadAllData(Class<T> clazz, Session session) {
        final CriteriaBuilder builder = session.getCriteriaBuilder();
        final CriteriaQuery<T> criteria = builder.createQuery(clazz);
        criteria.from(clazz);
        return session.createQuery(criteria).getResultList();
    }

    private static SessionFactory buildSessionFactory() {
        try {
            if (sessionFactory == null) {
                StandardServiceRegistry standardRegistry = new StandardServiceRegistryBuilder()
                        .configure("hibernate.cfg.xml").build();

                Metadata metaData = new MetadataSources(standardRegistry).getMetadataBuilder().build();

                sessionFactory = metaData.getSessionFactoryBuilder().build();
            }
            return sessionFactory;
        } catch (Throwable ex) {
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static void main(String args[]) {

        Map<String, Object> config = new HashMap<>();
        config.put("maxThreads", 10);
        config.put("storagePath", "/Users/krishna/my-docs");

        AppConfig appConfig = new AppConfig(1, config);

        try (Session session = sessionFactory.openSession()) {
            session.beginTransaction();
            session.persist(appConfig);
            session.flush();
            session.getTransaction().commit();

            List<AppConfig> appConfigs = loadAllData(AppConfig.class, session);
            for (AppConfig appConfig1 : appConfigs) {
                System.out.println(appConfig1);
            }

        }

    }
}

Total project structure looks like below.

Run App.java, you will see below messages in the console.

Aug 19, 2022 11:50:47 AM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate ORM core version 6.1.2.Final
Aug 19, 2022 11:50:47 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure
WARN: HHH10001002: Using built-in connection pool (not intended for production use)
Aug 19, 2022 11:50:47 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001005: Loaded JDBC driver class: org.postgresql.Driver
Aug 19, 2022 11:50:47 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001012: Connecting with JDBC URL [jdbc:postgresql://127.0.0.1:5432/test]
Aug 19, 2022 11:50:47 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001001: Connection properties: {password=****, user=postgres}
Aug 19, 2022 11:50:47 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001003: Autocommit mode: false
Aug 19, 2022 11:50:47 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections <init>
INFO: HHH10001115: Connection pool size: 20 (min=1)
Aug 19, 2022 11:50:47 AM org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl logSelectedDialect
INFO: HHH000400: Using dialect: org.hibernate.dialect.PostgreSQLDialect
Aug 19, 2022 11:50:48 AM org.hibernate.metamodel.internal.EntityInstantiatorPojoStandard resolveConstructor
INFO: HHH000182: No default (no-argument) constructor for class: com.sample.app.entity.AppConfig (class must be instantiated by Interceptor)
Aug 19, 2022 11:50:48 AM org.hibernate.resource.transaction.backend.jdbc.internal.DdlTransactionIsolatorNonJtaImpl getIsolatedConnection
INFO: HHH10001501: Connection obtained from JdbcConnectionAccess [org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess@76130a29] for (non-JTA) DDL execution was not in auto-commit mode; the Connection 'local transaction' will be committed and the Connection will be set into auto-commit mode.
Hibernate: 
    
    create table app_config (
       id integer not null,
        config jsonb,
        primary key (id)
    )
Aug 19, 2022 11:50:48 AM org.hibernate.engine.transaction.jta.platform.internal.JtaPlatformInitiator initiateService
INFO: HHH000490: Using JtaPlatform implementation: [org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform]
Hibernate: 
    insert 
    into
        app_config
        (config, id) 
    values
        (?, ?)
Hibernate: 
    select
        a1_0.id,
        a1_0.config 
    from
        app_config a1_0
AppConfig [id=1, config={storagePath=/Users/krishna/my-docs, maxThreads=10}]

Let’s query PostgreSQL and confirm the same.

test=# \d+ app_config;
                                        Table "public.app_config"
 Column |  Type   | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
--------+---------+-----------+----------+---------+----------+-------------+--------------+-------------
 id     | integer |           | not null |         | plain    |             |              | 
 config | jsonb   |           |          |         | extended |             |              | 
Indexes:
    "app_config_pkey" PRIMARY KEY, btree (id)
Access method: heap

test=# 
test=# 
test=# 
test=# SELECT * FROM app_config;
 id |                           config                            
----+-------------------------------------------------------------
  1 | {"maxThreads": 10, "storagePath": "/Users/krishna/my-docs"}
(1 row)

From the above snippet, you can confirm that the column config is defined with jsonb type.

 

You can download this application from this link.

 

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