I have an enum:
public enum NotificationType {
OPEN("open"),
CLOSED("closed");
public String value;
NotificationType(String value) {
this.value = value;
}
}
I want to pass the custom string open or closed rather than OPEN or CLOSED to entity. Currently, I've mapped it in the entity as follows:
@Enumerated(EnumType.STRING)
private NotificationType notificationType;
Which is the best way to store/ fetch enum value?
You can create a custom converter like this:
@Converter(autoApply = true)
public class NotificationTypeConverter implements AttributeConverter<NotificationType, String> {
@Override
public String convertToDatabaseColumn(NotificationType notificationType) {
return notificationType == null
? null
: notificationType.value;
}
@Override
public NotificationType convertToEntityAttribute(String code) {
if (code == null || code.isEmpty()) {
return null;
}
return Arrays.stream(NotificationType.values())
.filter(c -> c.value.equals(code))
.findAny()
.orElseThrow(IllegalArgumentException::new);
}
}
And perhaps you'll need to remove annotation from your notificationType field so that this converter takes effect.
NotificationType in a Map to reduce the stream overhead.
convertToDatabaseColumn method above is doing - converting enum to string and passing it on to the persistence layer for storageYes, basically you have to develop a custom converter for that but I suggest you use Optional to avoid dealing with null and exceptions.
Add in NotificationType:
public static Optional<NotificationType> getFromValue(String value) {
return Optional.ofNullable(value)
.flatMap(dv -> Arrays.stream(NotificationType.values())
.filter(ev -> dv.equals(ev.value))
.findFirst());
}
Create the required converter:
import javax.persistence.AttributeConverter;
import javax.persistence.Converter;
@Converter(autoApply = true)
public class NotificationTypeConverter implements AttributeConverter<NotificationType, String> {
@Override
public String convertToDatabaseColumn(NotificationType notificationType) {
return null == notificationType ? null : notificationType.value;
}
@Override
public NotificationType convertToEntityAttribute(String databaseValue) {
return NotificationType.getFromValue(databaseValue)
.orElse(null);
}
}
And now, you only have to modify your model:
@Entity
@Table
public class MyEntity {
@Convert(converter=NotificationTypeConverter.class)
private NotificationType notificationType;
}
NotificationTypefrom yourvalue, sinceNotificationType.valueOf(String)is case sensitive. (This implies you still keep the enum type in your entity but have a custom value persisted in the database.)