Persist a JSON object using Hibernate

Issue: BAEL-2353

persistence-modules/hibernate5/pom.xml

@@ -51,6 +51,11 @@
             <artifactId>hibernate-testing</artifactId>
             <version>5.2.2.Final</version>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -69,6 +74,7 @@
         <mariaDB4j.version>2.2.3</mariaDB4j.version>
         <h2database.version>1.4.196</h2database.version>
         <assertj-core.version>3.8.0</assertj-core.version>
+        <jackson.version>2.8.11.3</jackson.version>
     </properties>
 
 </project>

persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/persistjson/Customer.java

@@ -0,0 +1,80 @@
+package com.baeldung.hibernate.persistjson;
+
+import java.io.IOException;
+import java.util.Map;
+
+import javax.persistence.Convert;
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Table;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+@Entity
+@Table(name = "Customers")
+public class Customer {
+
+    @Id
+    private int id;
+
+    private String firstName;
+
+    private String lastName;
+
+    private String customerAttributeJSON;
+
+    @Convert(converter = HashMapConverter.class)
+    private Map<String, Object> customerAttributes;
+
+    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 getCustomerAttributeJSON() {
+        return customerAttributeJSON;
+    }
+
+    public void setCustomerAttributeJSON(String customerAttributeJSON) {
+        this.customerAttributeJSON = customerAttributeJSON;
+    }
+
+    public Map<String, Object> getCustomerAttributes() {
+        return customerAttributes;
+    }
+
+    public void setCustomerAttributes(Map<String, Object> customerAttributes) {
+        this.customerAttributes = customerAttributes;
+    }
+
+    private static final ObjectMapper objectMapper = new ObjectMapper();
+
+    public void serializeCustomerAttributes() throws JsonProcessingException {
+        this.customerAttributeJSON = objectMapper.writeValueAsString(customerAttributes);
+    }
+
+    public void deserializeCustomerAttributes() throws IOException {
+        this.customerAttributes = objectMapper.readValue(customerAttributeJSON, Map.class);
+    }
+
+}

persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/persistjson/HashMapConverter.java

@@ -0,0 +1,47 @@
+package com.baeldung.hibernate.persistjson;
+
+import java.io.IOException;
+import java.util.Map;
+
+import javax.persistence.AttributeConverter;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.baeldung.hibernate.interceptors.CustomInterceptor;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class HashMapConverter implements AttributeConverter<Map<String, Object>, String> {
+
+    private static final Logger logger = LoggerFactory.getLogger(CustomInterceptor.class);
+
+    private final ObjectMapper objectMapper = new ObjectMapper();
+
+    @Override
+    public String convertToDatabaseColumn(Map<String, Object> customerInfo) {
+
+        String customerInfoJson = null;
+        try {
+            customerInfoJson = objectMapper.writeValueAsString(customerInfo);
+        } catch (final JsonProcessingException e) {
+            logger.error("JSON writing error", e);
+        }
+
+        return customerInfoJson;
+    }
+
+    @Override
+    public Map<String, Object> convertToEntityAttribute(String customerInfoJSON) {
+
+        Map<String, Object> customerInfo = null;
+        try {
+            customerInfo = objectMapper.readValue(customerInfoJSON, Map.class);
+        } catch (final IOException e) {
+            logger.error("JSON reading error", e);
+        }
+
+        return customerInfo;
+    }
+
+}

persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/persistjson/PersistJSONUnitTest.java

@@ -0,0 +1,111 @@
+package com.baeldung.hibernate.persistjson;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Properties;
+
+import org.hibernate.HibernateException;
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.boot.MetadataSources;
+import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.cfg.Configuration;
+import org.hibernate.service.ServiceRegistry;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+public class PersistJSONUnitTest {
+
+    private Session session;
+
+    @Before
+    public void init() {
+        try {
+            Configuration configuration = new Configuration();
+
+            Properties properties = new Properties();
+            properties.load(Thread.currentThread()
+                .getContextClassLoader()
+                .getResourceAsStream("hibernate-persistjson.properties"));
+
+            configuration.setProperties(properties);
+
+            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties())
+                .build();
+            MetadataSources metadataSources = new MetadataSources(serviceRegistry);
+            metadataSources.addAnnotatedClass(Customer.class);
+
+            SessionFactory factory = metadataSources.buildMetadata()
+                .buildSessionFactory();
+
+            session = factory.openSession();
+        } catch (HibernateException | IOException e) {
+            fail("Failed to initiate Hibernate Session [Exception:" + e.toString() + "]");
+        }
+    }
+
+    @After
+    public void close() {
+        if (session != null)
+            session.close();
+    }
+
+    @Test
+    public void givenCustomer_whenCallingSerializeCustomerAttributes_thenAttributesAreConverted() throws IOException {
+
+        Customer customer = new Customer();
+        customer.setFirstName("first name");
+        customer.setLastName("last name");
+
+        Map<String, Object> attributes = new HashMap<>();
+        attributes.put("address", "123 Main Street");
+        attributes.put("zipcode", 12345);
+
+        customer.setCustomerAttributes(attributes);
+
+        customer.serializeCustomerAttributes();
+
+        String serialized = customer.getCustomerAttributeJSON();
+
+        customer.setCustomerAttributeJSON(serialized);
+        customer.deserializeCustomerAttributes();
+
+        Map<String, Object> deserialized = customer.getCustomerAttributes();
+
+        assertEquals("123 Main Street", deserialized.get("address"));
+    }
+
+    @Test
+    public void givenCustomer_whenSaving_thenAttributesAreConverted() {
+
+        Customer customer = new Customer();
+        customer.setFirstName("first name");
+        customer.setLastName("last name");
+
+        Map<String, Object> attributes = new HashMap<>();
+        attributes.put("address", "123 Main Street");
+        attributes.put("zipcode", 12345);
+
+        customer.setCustomerAttributes(attributes);
+
+        session.beginTransaction();
+
+        int id = (int) session.save(customer);
+
+        session.flush();
+        session.clear();
+
+        Customer result = session.createNativeQuery("select * from Customers where Customers.id = :id", Customer.class)
+            .setParameter("id", id)
+            .getSingleResult();
+
+        assertEquals(2, result.getCustomerAttributes()
+            .size());
+    }
+
+}

persistence-modules/hibernate5/src/test/resources/hibernate-persistjson.properties

@@ -0,0 +1,7 @@
+hibernate.connection.driver_class=org.h2.Driver
+hibernate.connection.url=jdbc:h2:mem:mydb1;DB_CLOSE_DELAY=-1
+hibernate.connection.username=sa
+hibernate.dialect=org.hibernate.dialect.H2Dialect
+
+hibernate.show_sql=true
+hibernate.hbm2ddl.auto=create-drop