Enable converting enums to integer (built-in or custom converter) [DATAJDBC-408]

[spring-projects-issues]

Fábio Coutinho Valente opened DATAJDBC-408 and commented

I'm changing my application from Spring Data JPA to Spring Data JDBC, and I have one column on my table that saves an integer of the ordinal.
According to documentation Spring Data JDBC only allows converting enums to string out of the box. So I tried a workaround with custom converters.

I created a custom converter with @ReadingConverter and could read/convert properly to my enum value according to the integer on my table.
I tried creating a custom converter with @WritingConverter annotation, but its not being executed instead the converter org.springframework.core.convert.support.EnumToStringConverter is being called.
After some debugging I found the map javaToDbType in class BasicRelationalPersistentProperty to be the resposible for that due to this static line

javaToDbType.put(Enum.class, String.class)

If there is no built-in convertion enum to integer, could you allow custom converter to be used instead?
Is there any other way to convert enum values into integer (ordinal number)?

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2 votes, 3 watchers

[spring-projects-issues]

Jens Schauder commented

Thanks for raising this.

If we would handle Enum values with a CustomConversion by default which could be replaced at configuration time this should be possible and not too difficult to do

[lpgph]

I also had this problem. I'm Custom enumeration value ,eg:

public enum StateEnum{
  ACTIVATED(1),
  DEACTIVATED(2);

  StateEnum(Integer value) {
    this.value = value;
  }

  private final Integer value;

  public int getValue() {
    return value;
  }
}

register converter to JdbcCustomConversions

@Slf4j
@WritingConverter
public class StateToIntegerConverter implements Converter<StateEnum,Integer> {
  @Override
  public Integer convert(StateEnum source) {
    return source.getValue();
  }
}

but always use org.springframework.core.convert.support.EnumToStringConverter

Temporary plan

@Slf4j
@WritingConverter
public class StateToIntegerConverter implements Converter<StateEnum,String> {
  @Override
  public String convert(StateEnum source) {
    return String.valueOf(source.getValue());
  }
}

[ahmet-voys]

We also hit this issue. We have custom integer values associated with enums. We have custom WriteConverter classes.
But during write, it tries to write the String value instead. Is there any workaround you can suggest?

 @WritingConverter
    static class MyEnumWritingConverter implements Converter<MyEnum, Integer> {

        @Override
        public Integer convert(@NonNull MyEnum e) {
            return e.getDbIndex();
        }
    }

[lesiak]

Proposed workaround in Spring-Boot 2.6.2:
https://stackoverflow.com/a/70792020/1570854

[hilmarf]

isn't it solved with: https://github.com/spring-projects/spring-framework/blob/main/spring-core/src/main/java/org/springframework/core/convert/support/EnumToIntegerConverter.java ?

[schauder]

Thanks for finding this. Yes I think this should be considered resolved.

Leaving it open for a bit for the OP to veto a close.

[schauder]

Closing this as solved as indicated by the comment above.

[peteraramaldes]

@schauder
Same problem here with spring-data-jdbc:2.4.2
Do we have any updates on this?

[schauder]

We might have closed that prematurely.
@peteraramaldes Can you verify that this issue still exists in Spring Data JDBC 3.x?