Typescript：如何在实例成员属性（mixin）中使用方法装饰器？

Question

Background

We have implemented a mixin like this (simplified):

export type Constructor<I> = new (...args: any[]) => I;

export interface IBaseService<T = any> {
  create: (data: any) => Promise<T>;
}

export function BaseService<T>(entity: Constructor<T>): Type<IBaseService<T>> {
  class BaseServiceHost implements IBaseService<T> {
    public repository: Repository<T>;

    create(data: DeepPartial<T>): Promise<T> {
      const newResource = this.repository.create(data);
      return this.repository.save(newResource);
    }

  }
  return BaseServiceHost;
}

Now my service extends BaseService like this:

@Injectable()
export class ResponseService extends BaseService(ResponseEntity) {
  private readonly respondentService: RespondentService;
  private readonly surveyService: SurveyService;

  create = async (data: ResponseInput): Promise<ResponseEntity> => {
    const respondent = await this.respondentService.findByNaturalKey(data.respondentKey);
    const survey = await this.surveyService.findById(data.surveyId);
    return super.create({ respondent, survey, ...data })
  };

... and this works fine.

PS.: create has to be a property now, otherwise I'd get the following error:

Class 'IBaseTenantService<ResponseEntity>' defines instance member property 'create',
but extended class 'ResponseService' defines it as instance member function.

Problem

The create method (now a property), needs the method decorator Transactional() , but the construction

  @Transactional()  // <--- error here
  create = async (data: ResponseInput): Promise<ResponseEntity> => {
    const respondent = await this.respondentService.findByNaturalKey(data.respondentKey);
    const survey = await this.surveyService.findById(data.surveyId);
    return super.create({ respondent, survey, ...data })
  };

gives the following error:

The return type of a property decorator function must be either 'void' or 'any'.
  Unable to resolve signature of property decorator when called as an expression.

Question

How to use the Transactional() in the create property? Workarounds?

Answer 1

this might sound dumb but ever you tried this:

  @Transactional()
  async create(data: ResponseInput): Promise<ResponseEntity> {
    const respondent = await this.respondentService.findByNaturalKey(data.respondentKey);
    const survey = await this.surveyService.findById(data.surveyId);
    return super.create({ respondent, survey, ...data })
  };

?