Can I use one Enum as DiscriminatorType and Column in parent class?

Question

Im creating a repair service with different types of repair. I have a SINGLE_TABLE inheritance and I differentiate them with an Enum repair_Type, I also want to have Repair_Type as a column so I can sort and search repairs by type but I am getting No enum constant exception.

Here's my code:

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(discriminatorType = DiscriminatorType.STRING)
public abstract class Repair {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public long repairID;

    @ManyToOne
    private Customer customerID;

    @Enumerated(EnumType.STRING)
    private RepairType repairType;

    @OneToMany
    private List<Employee> employeeList;

    @Enumerated(EnumType.STRING)
    private DeliveryOption deliveryOption;

    private boolean expressRepair;

    private boolean cleanProduct;

    @Column(length = 64)
    private String productImage;

    @OneToOne
    private Brand brand;

    private String model;

    private int size;

    private int buildYear;

    @Temporal(TemporalType.TIMESTAMP)
    private Date dateCreated;

    @Column(nullable = false)
    private String repairNote;
}
No getters and setters for brevity

RepairType:

public enum RepairType {
    KITE(Types.KITE),
    BOARD(Types.BOARD),
    BAR(Types.BAR),
    WETSUIT(Types.WETSUIT);

    private String type;

    RepairType(String type) {
    }

    public static class Types {
        public static final String KITE = "Kite";
        public static final String BOARD = "Board";
        public static final String BAR = "Bar";
        public static final String WETSUIT = "Wetsuit";
    }
}

Example of a child class repair type (I have four)

@Entity
@DiscriminatorValue(value = RepairType.Types.BAR)
public class BarRepair extends Repair {

    private boolean lengthCheck;

    public BarRepair() {
    }

    public BarRepair(long repairID, Customer customerID, List<Employee> employeeList, DeliveryOption deliveryOption, boolean expressRepair, boolean cleanProduct, String productImage, Brand brand, String model, int size, int buildYear, Date dateCreated, String repairNote, boolean lengthCheck) {
        super(repairID, customerID, employeeList, deliveryOption, expressRepair, cleanProduct, productImage, brand, model, size, buildYear, dateCreated, repairNote);
        this.lengthCheck = lengthCheck;
    }

    public boolean isLengthCheck() {
        return lengthCheck;
    }

    public void setLengthCheck(boolean lengthCheck) {
        this.lengthCheck = lengthCheck;
    }
}

Answer 1

Enum mapped using @Enumerated(EnumType.STRING) are mapped using the .name() representation of the enum. So in your case: KITE , BOARD , ...

Because you are saving them as Kite , Board and so on, Hibernate ORM cannot find the enum for each String value.

I think you need to use an @AttributeConverter :

@Converter
public static class RepairTypeConverter
        implements AttributeConverter<RepairType, String> {

    public Character convertToDatabaseColumn( RepairType value ) {
        if ( value == null ) {
            return null;
        }

        return value.getType();
    }

    public RepairType convertToEntityAttribute( String value ) {
        if ( value == null ) {
            return null;
        }

        return RepairType.fromType( value );
    }
}

Where getType() and fromType() are used to convert from the enum to the type and vice-versa.

Then you can map the attribute with:

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="repair_Type", discriminatorType = DiscriminatorType.STRING)
public abstract class Repair {
    ...
    
    @Convert( converter = RepairTypeConverter.class )
    @Column(name = "repair_Type)
    private RepairType repairType;

    ...
}

See the Hibernate ORM documentation for more details .