Is it possible to have generic type in swagger spec in nest js?

Question

I'm implementing a POST endpoint which takes such a DTO as an input:

export class GenericEventDto<D, A> {
  @ApiProperty({ type: D }) // <- does not work
  @Expose()
  data: D

  @ApiProperty({ type: A })
  @Expose()
  attributes: A // <- same

  @ApiProperty()
  @Expose()
  messageId: string
}

In swagger docs data and attributes props appear to be empty object. Controller code looks like this:

export class Controller {
  @ApiBody({ type: GenericEventDto<ConcreteData, ConcreteAttributes> })
  async handleIncomingMessage(
    @Body() event: GenericEventDto<ConcreteData, ConcreteAttributes>
  ): Promise<void> {
    // do smth
  }
}

Is it possible to have generic type in swagger spec? This GenericEventDto will be reused later for other endpoints and I would like to avoid code duplication

score 0 · Accepted Answer · answered Jun 14 '23 at 21:25

The docs specifically mention about this

Since TypeScript does not store metadata about generics or interfaces, when you use them in your DTOs, SwaggerModule may not be able to properly generate model definitions at runtime

You'd need to make a mixin rather than a generic type. A mixin in this case is a function that returns a class definition

Is it possible to have generic type in swagger spec in nest js?

1 Answers1