How to map with the help of Automapper (TypeScript) the entries of an array filled with different DTOs?

Question

I'm using the TypeScript library "Automapper" in my NestJS backend to convert an answer of MongoDb/Mongoose to an DTO. That's how the answer looks like:

{
    "_id": "mongo-object-id",
    "widgets": [
      {
        "id": "UUID",
        "type": "IMAGE",
        "zIndex": "0",
        "position": { "x": 1, "y": 2 },
        "pinned": false,
        "height":500,
        "width":1000
      },
      {
        "id": "UUID",
        "type": "CONVERSATION",
        "zIndex": "1",
        "position": { "x": 3, "y": 7 },
        "pinned": false,
        "participants": ["UUID1","UUID2"]
      }
    ]
  }

My problem is, that I don't know how to convert the entries of the "widgets" array to different DTOs (ImageDTO, ConversationDTO) based on the "type" attribute/discriminator.

How can I solve that?

Currently I use the following:

mapper.createMap(MeetingSpace, MeetingSpaceDto).forMember(
        (destination) => destination.widgets,
        mapWith(WidgetDto, Widget, (source) => source.widgets)
      );

But I have to find a way to map a "Widget" to an "ImageDto" or "ConversationDto" because of the "type".

mapWith(ImageDto, Widget, (source) => source.widgets)
mapWith(ConversationDto, Widget, (source) => source.widgets)

Answer 1

I know this is a bit late - but I just came across the same need.

You need to define the mapping from Widget to ImageDTO

createMap(mapper, Widget, ImageDTO);

Then use the map function on the collection:

return source.widgets.map(widget => mapper.map(widget, Widget, ImageDTO);