Nest.js 中的嵌套拦截器

Question

How to implement a nested interceptor in Nest.js?

I have two interceptors: UsersInterceptor and PostsInterceptor

UsersInterceptor:

@Injectable()
export class UsersInterceptor<T> implements NestInterceptor<T, Response<T>> {
  intercept(context: ExecutionContext, next: CallHandler): Observable<Response<T>> {
    return next.handle().pipe(map(data => ({
      id: data._id,
      email: data.email,
      createdAt: data.createdAt
    })));
  }
}

PostsInterceptor:

@Injectable()
export class PostsInterceptor<T> implements NestInterceptor<T, Response<T>> {
  intercept(context: ExecutionContext, next: CallHandler): Observable<Response<T>> {
    return next.handle().pipe(map(data => ({
      id: data._id,
      title: data.title,
      content: data.content,
      user: {}, // I want the UsersInterceptor result here. I have the user's data in data.user
      createdAt: data.createdAt
    })));
  }
}

Now, I want to put the UserInterceptor 's result into the user object in the PostsInterceptor when I use it.

Answer 1

As described in the request lifecycle docs , interceptors work on the incoming request in the order they are bound, and on the outgoing response in the inverse order they are bound. This means that if you bind your interceptors like @UseInterceptors(PostInterceptor, UserInterceptor) then you should be able to see UserInterceptor 's return in the PostInterceptor