NestJS从ExceptionFilter抛出

Question

我尝试使用ExceptionFilter将异常映射到它们的HTTP对应物。

这是我的代码：

@Catch(EntityNotFoundError)
export class EntityNotFoundFilter implements ExceptionFilter {
    catch(exception: EntityNotFoundError, _host: ArgumentsHost) {
        throw new NotFoundException(exception.message);
    }
}

但是，当执行过滤器代码时，我得到了一个UnhandledPromiseRejectionWarning

 (node:3065) UnhandledPromiseRejectionWarning: Error: [object Object]
    at EntityNotFoundFilter.catch ([...]/errors.ts:32:15)
    at ExceptionsHandler.invokeCustomFilters ([...]/node_modules/@nestjs/core/exceptions/exceptions-handler.js:49:26)
     at ExceptionsHandler.next ([...]/node_modules/@nestjs/core/exceptions/exceptions-handler.js:13:18)
     at [...]/node_modules/@nestjs/core/router/router-proxy.js:12:35
     at <anonymous>
     at process._tickCallback (internal/process/next_tick.js:182:7)
 (node:3065) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 5)

我怎样才能解决这个问题 ？

Answer 1

ExceptionFilter始终是在发送响应之前调用的最后一个位置，它负责构建响应。你不能在ExceptionFilter中重新抛出异常。

@Catch(EntityNotFoundError)
export class EntityNotFoundFilter implements ExceptionFilter {
  catch(exception: EntityNotFoundError, host: ArgumentsHost) {
    const response = host.switchToHttp().getResponse();
      response.status(404).json({ message: exception.message });
  }
}

---

或者，您可以创建一个转换错误的Interceptor：

@Injectable()
export class NotFoundInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
    // next.handle() is an Observable of the controller's result value
    return next.handle()
      .pipe(catchError(error => {
        if (error instanceof EntityNotFoundError) {
          throw new NotFoundException(error.message);
        } else {
          throw error;
        }
      }));
  }
}

在这个codesandbox尝试一下。

Answer 2

基于Kim Kern解决方案，我创建了这个抽象类

export abstract class AbstractErrorInterceptor<T> implements NestInterceptor {
    protected interceptedType: new (...args) => T;

    intercept(
        context: ExecutionContext,
        call$: Observable<any>,
    ): Observable<any> | Promise<Observable<any>> {
        return call$.pipe(
            catchError(exception => {
                if (exception instanceof this.interceptedType) {
                    this.handleError(exception);
                }
                throw exception;
            }),
        );
    }

    abstract handleError(exception: T);
}

还有一些实现

export class EntityNotFoundFilter extends AbstractErrorInterceptor<EntityNotFoundError> {
    interceptedType = EntityNotFoundError;

    handleError(exception: EntityNotFoundError) {
        throw new NotFoundException(exception.message);
    }
}

Answer 3

您正在创建自己的基于HTTP的异常类的版本，这已经与NestJS一起提供，这似乎很奇怪。默认情况下，这些将自动转换为具有正确错误代码的HTTP响应。你正在增加拦截器和抽象类实现的开销，而你可以抛出NestJS错误并免费获得它。这是您所指的内置机制。

throw new BadRequestException('you done goofed');

结果是：

{"statusCode":400,"error":"Bad Request","message":"you done goofed"}

Codesandbox (adapted from Kim's)