Mapping Enum variants with same enum keys

[aki-ks]

Is your feature request related to a problem? Please describe.

When I'm mapping between two kind of datastructures, I'm often facing the problem that they're both using equivalent enums but these encode the values as different constants or have different variant names.

class UserEntity {
  @AutoMap()
  name: string;

  @AutoMap()
  favoriteColor: ColorEntity;
}

enum ColorEntity {
  Red = 'r',
  Green = 'g',
  Blue = 'b',
  Other = 'o',
}

class UserDto {
  @AutoMap()
  name: string;

  @AutoMap()
  favoriteColor: ColorDto;
}

enum ColorDto {
  Red = 'red',
  Green = 'green',
  Blue = 'blue',
  Custom = 'custom',
}

How can I teach AutoMapper to map ColorEntity to ColorDto?

Describe the solution you'd like

I'd love to see automapper handle enums like any other class, so a mapping between two enums can be defined. The variants of the enum are mapped like typescript fields:

• When both enums have variants of the same name, then they are mapped to each other (Red, Green, Blue in the upper example).
• Variants that the two enum types do not have in common require a manual mapping (Custom/Other in the example)

mapper.createMap(ColorEntity, ColorDto)
  .forMember(dto => dto.Custom, mapFrom(entity => entity.Other))

Describe alternatives you've considered

No response

Additional context

I barely know typescript reflection, so I can't judge whether this idea is realizable.
Can the variants of enums be discovered via reflection or whatever is required for this feature?

[nartc]

Thank you for showing interest and requesting this feature.

However, Enums are complicated: string enums, number enums, mixed enums, and const enums... Hence, it is tricky to get some generic support for enum in this sense.

What I can suggest you to do is to create a Resolver and use a switch statement

export const colorResolver: Resolver<
  {color: ColorEntity},
  {color: ColorDto},
  ColorDto
> = {
  resolve(source: TypeConverterSource): ColorDto {
    switch (source.color) {
      case Color.Red:
        return ColorDto.Red;
      case Color.Green:
        return ColorDto.Green;
      case Color.Blue:
        return ColorDto.Blue;
    }
  },
};

then use it on a mapFrom()

mapper.createMap(Source, Destination)
   .forMember(d => d.color, mapFrom(colorResolver))

[nartc]

@aki-ks can we close this issue?

[aki-ks]

If you want to leave it at your suggestion and don't plan to add extended support for enums to the library, then sure.
Your recommendation has already helped me a lot. 👍

[nartc]

Thank you. I'll convert this to a discussion then :)