We need a domain model object to map the records inserted into our database. To do this, we will use the JPA specification; so, we will create an entity class for this purpose, as follows:

1. Let's create a new Java package named model, in order to store the data model class. The fully qualified package name will be com.packtpub.thorntail.footballplayermicroservice.model.
2. Next, we will build the domain class, named FootballPlayer:

package   com.packtpub.thorntail.footballplayermicroservice.model;

   import java.math.BigInteger;
   ...

   /**
    * Domain model class that maps the data stored into football_player table
    * inside database.
    *
    * @author Mauro Vocale
    * @version 1.0.0 15/08/2018
    */
   @Entity
   @Table(name = "football_player")
   @XmlRootElement
   @NamedQueries({
    @NamedQuery(name = "FootballPlayer.findAll", query
             = "SELECT f FROM FootballPlayer f")
    })
   public class FootballPlayer {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Integer id;

    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 50)
    @Column(name = "name")
    private String name;

    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 50)
    @Column(name = "surname")
    private String surname;

    @Basic(optional = false)
    @NotNull
    @Column(name = "age")
    private int age;

    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 50)
    @Column(name = "team")
    private String team;

    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 50)
    @Column(name = "position")
    private String position;

    @Column(name = "price")
    private BigInteger price;

    public FootballPlayer() {
    }

    public FootballPlayer(String name, String surname, int age,
             String team, String position, BigInteger price) {
        this.name = name;
        this.surname = surname;
        this.age = age;
        this.team = team;
        this.position = position;
        this.price = price;
    }

    ...

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (id != null ? id.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        if (!(object instanceof FootballPlayer)) {
            return false;
        }
        FootballPlayer other = (FootballPlayer) object;
        return !((this.id == null && other.getId() != null)    
            || (this.id != null && !this.id.equals(other.getId())));
    }

    ...

   }

3. To complete the management of the database access operations, we need to configure the persistence.xml file, inside  src/main/resources/META-INF directory, where we will store all the configurations related to our persistence layer:

<?xml   version="1.0" encoding="UTF-8" standalone="no"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.1"   xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
     <persistence-unit name="FootballPlayerPU" transaction-type="JTA">
         <jta-data-source>java:/jboss/datasources/FootballPlayerDS</jta-data-source>
         <properties>
             <property name="javax.persistence.schema-generation.database.action"   
                 value="drop-and-create"/>
             <property name="javax.persistence.schema-generation.drop-source"   
                 value="metadata"/>
             <property name="javax.persistence.schema-generation.create-script  
                 source"
                 value="META-INF/create.sql" />
             <property name="javax.persistence.sql-load-script-source" 
                 value="META-INF/load.sql"/>
         </properties>
     </persistence-unit>
</persistence>

The most important elements are as follows:

• The name of the persistence unit (FootballPlayerPU)
• The transaction type, JTA (which means that we demand to the container the management of the transactions)
• The data source JNDI name to use (java:/jboss/datasources/FootballPlayerDS)
• The load script source that will preload a subset of data into the database

4. Finally, we will create the default project (the defaults.yml file) in the src/main/resources/ directory, where we will define the data source, FootballPlayerDS, which contains the configuration to connect to the database:

swarm:
  datasources:
    data-sources:
      FootballPlayerDS:
        driver-name: postgresql
        connection-url:jdbc:postgresql://localhost:5532/football_players_registry
        user-name: postgres
        password: postgresPwd
        valid-connection-checker-class-name: org.jboss.jca.adapters.jdbc.extensions.postgres.PostgreSQLValidConnectionChecker
        validate-on-match: true
        background-validation: false
        exception-sorter-class-name:   org.jboss.jca.adapters.jdbc.extensions.postgres.PostgreSQLExceptionSorter

5. We will set the relative dependency in a Maven pom.xml file, as follows:

<properties>
    ...
    <version.postgresql>9.4.1207</version.postgresql>
</properties>
<dependency>
    <groupId>io.thorntail</groupId>
    <artifactId>datasources</artifactId>
    <scope>provided</scope>
</dependency>
<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>${version.postgresql}</version>
</dependency>

Declaring the vendor JDBC library dependency, Thorntail will automatically detect and install the driver.