如何利用角度8拦截器从json中提取特殊值

Question

我有ErrorInterceptor，它从.net核心2.2后端获取错误消息。对于单个消息，它正确地显示了消息，但是对于多条消息，它失败了。

My ErrorInterceptor.ts :
  @Injectable()
  export class ErrorInterceptor implements HttpInterceptor {
    intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        return next.handle(req).pipe(
            catchError(err => {
                if (err instanceof HttpErrorResponse) {
                    if (err.status === 401) {
                        return throwError(err.statusText);
                    }
                    const applicationError = err.headers.get('Application-Error');
                    if (applicationError) {
                        console.error(applicationError);
                        return throwError(applicationError);
                    }
                    const serverError = err.error;
                    let modalStateErrors = '';
                    if (serverError && typeof serverError === 'object') {
                        for (const key in serverError) {
                            if (serverError[key]) {
                                modalStateErrors += serverError[key] + '\n';
                            }
                        }
                    }
                    return throwError(modalStateErrors || serverError || 'Server Error');
                }
            })
        )
    }
}

export const ErrorInterceptorProvide = {
    provide: HTTP_INTERCEPTORS,
    useClass: ErrorInterceptor,
    multi: true
}

用于单个错误的json文件示例，该文件显示正确的消息：

 "Username already exists"

多个错误消息的例子，我想从json中提取错误，而不是标题和其他任何东西。准确地说，错误内部的错误信息。我正在使用警报显示这条信息。Json结果：

{"errors":{"Password":["password is required"],"Username":["username is required"]},"title": "One or 
 more validation errors occurred.","status":400,"traceId":"0HLRU5MDVJPEI:00000004"}

如何显示准确的错误信息？

Answer 1

由于您的错误消息驻留在errors属性上，而错误驻留在数组上，所以您可以尝试以下代码。

​

 if (serverError && typeof serverError === 'object') {
     const errors = serverError.errors;
     for (const key in errors) {
         if (Array.isArray(errors[key])) {
             modalStateErrors += errors[key].join('\n');
             }
         }
    }

​