Mapping enum to String

[Paul Strugnell]

Hi all

I have noticed that my MapStruct-generated mapper classes use toString() to convert an enum value to a String object, but this is unsafe as somebody may later override toString() on the enum class, thus causing the mapping to change.

I want to the mapper to use name(), since it is guaranteed to return the enum value exactly as declared.

Is there any way to use name() instead of toString()?

Thanks!

[Gunnar Morling]

Hi,

There is no way to do this, but I agree that this would be better.

I have filed https://github.com/mapstruct/mapstruct/issues/540 for this and assigned it to the upcoming CR1 release. Would you be interested in contributing a fix? Should probably just be a small change in https://github.com/mapstruct/mapstruct/blob/master/processor/src/main/java/org/mapstruct/ap/conversion/EnumStringConversion.java.

Thanks,

--Gunnar

--
You received this message because you are subscribed to the Google Groups "mapstruct-users" group.
To unsubscribe from this group and stop receiving emails from it, send an email to mapstruct-use...@googlegroups.com.
To post to this group, send email to mapstru...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Paul Strugnell]

I'm tempted to simply change toString() to name(), but I think this would only be appropriate if there are no valid use cases for toString(). I wouldn't want to break anyone's code.

Would it be possible/worthwhile to make it configurable (e.g. using an annotation on the mapper) so that developers can choose the implementation they want?

[Paul Strugnell]

I have created a pull request for changing toString() to name() - https://github.com/mapstruct/mapstruct/pull/541

[Gunnar Morling]

IMO it's safe to do the proposed change.

It won't affect anybody not overriding toString() (which I think is the vast majority of cases). For those who do override it, the current approach is not optimal anyways, because it makes the generated mapping asymmetric: enum -> string is mapped via toString(), whereas string -> enum is mapped via valueOf() which expects the enum member name.

I don't think it's worth the have an option for this. Those who really need to customize this, can do so via their own mapping method on a hand-written mapper and plugging this in.

Thanks for your PR. I will merge it ASAP. To be extra-safe, we can add an entry to the migration notes.

Cheers,

--Gunnar