Solve the Java Spring Boot Enum

I had a hard time solving the org.hibernate.type.descriptor.java.EnumJavaTypeDescriptor.fromOrdinal(EnumJavaTypeDescriptor.java:76)error that I got while reading the value from the database.

Background

While using the Spring Boot application, I saved some values in the database as an INT that I had to map back with the enum UserRole. The challenge: I used id and name in the enum, but instead of starting the id value from 0, I started the ID value from 1.

This is the point the story started to challenge itself.

The actual problem is instead of mapping the id of the enum while populating the object back to the Java object. It started reading the ordinal value. And I was feeling clueless even after debugging.

Every blog that I was reading was suggesting to change the id to 0 so that the underlying exception (shown below) can be avoided.

ERROR 13992 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.ArrayIndexOutOfBoundsException: Index 2 out of bounds for length 2] with root cause
java.lang.ArrayIndexOutOfBoundsException: Index 2 out of bounds for length 2 ...

My POJO mappings were:

User POJO

@Entity
@Table(name = "USER")
@Getter
@Setter
@NoArgsConstructor(force = true)
public class User {

  @Id
  @Column(name = "ID")
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  @Column(name = "ROLE")
  @NotNull(message = "Role is required")
  @JsonAlias("roleId")
  private UserRole roleId;

  @Column(name = "NAME")
  @NotNull(message = "User Name is required")
  private Sting name;

}

UserRole POJO

public enum UserRole {

  ADMIN(1, "Admin"),
  USER(2, "User");

  private final int id;
  private final String name;

  private UserRole(final int id, final String name) {
    this.id = id;
    this.name = name;
  }

  public int getId() {
    return id;
  }

  public String getName() {
    return name;
  }

  public static UserRole valueOf(final Integer id) {
    if (id == null) {
      return null;
    }
    for (UserRole type : UserRole.values()) {
      if (type.id == id) {
        return type;
      }
    }
    return null;
  }
}

Solution

When such a situation arises where you have to manipulate the DB values as per your enum, you can use the: 

javax.persistence.Converter

Here's How!

I added the following code to the User POJO:

  @Convert(converter = UserRole.UserRoleConverter.class)
  @Column(name = "ROLE")
  @NotNull(message = "Role is required")
  @JsonAlias("roleId")
  private UserRole roleId;

And the below code to the UserRole POJO:

  @Converter(autoApply = true)
  public static class UserRoleConverter implements
      AttributeConverter<UserRole, Integer> {

    @Override
    public Integer convertToDatabaseColumn(UserRole attribute) {
      if (attribute == null) {
        throw new BadRequestException("Please provide a valid User Role.");
      }

      return attribute.getId();
    }

    @Override
    public UserRole convertToEntityAttribute(Integer dbData) {
      return UserRole.valueOf(dbData);
    }
  }

This converter maps the value fetched from the DB to the enum value by internally calling the valueOf() method.

I was facing this error, and this approach solved the problem for me. I am pretty sure it will solve your problem too.

Do let me know in the comments if you find the solution useful. :)