Is there a way to get the reason a HystrixCommand failed when using the #HystrixCommand annotation within a Spring Boot application? It looks like if you implement your own HystrixCommand, you have access to the getFailedExecutionException but how can you get access to this when using the annotation? I would like to be able to do different things in the fallback method based on the type of exception that occurred. Is this possible?
I saw a note about HystrixRequestContext.initializeContext() but the HystrixRequestContext doesn't give you access to anything, is there a different way to use that context to get access to the exceptions?
Simply add a Throwable parameter to the fallback method and it will receive the exception which the original command produced.
From https://github.com/Netflix/Hystrix/tree/master/hystrix-contrib/hystrix-javanica
#HystrixCommand(fallbackMethod = "fallback1")
User getUserById(String id) {
throw new RuntimeException("getUserById command failed");
}
#HystrixCommand(fallbackMethod = "fallback2")
User fallback1(String id, Throwable e) {
assert "getUserById command failed".equals(e.getMessage());
throw new RuntimeException("fallback1 failed");
}
I haven't found a way to get the exception with Annotations either, but creating my own Command worked for me like so:
public static class DemoCommand extends HystrixCommand<String> {
protected DemoCommand() {
super(HystrixCommandGroupKey.Factory.asKey("Demo"));
}
#Override
protected String run() throws Exception {
throw new RuntimeException("failed!");
}
#Override
protected String getFallback() {
System.out.println("Events (so far) in Fallback: " + getExecutionEvents());
return getFailedExecutionException().getMessage();
}
}
Hopefully this helps someone else as well.
As said in the documentation Hystrix-documentation getFallback() method will be thrown when:
Whenever a command execution fails: when an exception is thrown by construct() or run()
When the command is short-circuited because the circuit is open
When the command’s thread pool and queue or semaphore are at capacity
When the command has exceeded its timeout length.
So you can easily get what raised your fallback method called by assigning the the execution exception to a Throwable object.
Assuming your HystrixCommand returns a String
public class ExampleTask extends HystrixCommand<String> {
//Your class body
}
do as follows:
#Override
protected ErrorCodes getFallback() {
Throwable t = getExecutionException();
if (circuitBreaker.isOpen()) {
// Log or something
} else if (t instanceof RejectedExecutionException) {
// Log and get the threadpool name, could be useful
} else {
// Maybe something else happened
}
return "A default String"; // Avoid using any HTTP request or ypu will need to wrap it also in HystrixCommand
}
More info here
I couldn't find a way to obtain the exception with the annotations, but i found HystrixPlugins , with that you can register a HystrixCommandExecutionHook and you can get the exact exception in that like this :
HystrixPlugins.getInstance().registerCommandExecutionHook(new HystrixCommandExecutionHook() {
#Override
public <T> void onFallbackStart(final HystrixInvokable<T> commandInstance) {
}
});
The command instance is a GenericCommand.
Most of the time just using getFailedExecutionException().getMessage() gave me null values.
Exception errorFromThrowable = getExceptionFromThrowable(getExecutionException());
String errMessage = (errorFromThrowable != null) ? errorFromThrowable.getMessage()
this gives me better results all the time.
Related
I have a method in OneServiceImpl class as follows. In that class I am calling an interface method from another class.
public class OneServiceImpl {
//created dependency
final private SecondService secondService;
public void sendMessage(){
secondService.validateAndSend(5)
}
}
public interface SecondService() {
public Status validateAndSend(int length);
}
public class SecondServiceImpl {
#Override
public Status ValidateAndSend(int length) {
if(length < 5) {
throw new BadRequestException("error", "error");
}
}
}
Now when I am try to perform unit test on OneServiceImpl I am not able to throw a BadRequestException.
when(secondService.validateAndSend(6)).thenThrow(BadRequestException.class);
Not quite sure what your use case is, but I think you should write an own test to accept and test an exception.
#Test(expected = BadRequestException.class)
public void testValidateAndSend(){
SecondService secondService = new SecondService();
secondservice.ValidateAndSend(6); //method should be lowercase
}
Not sure this is the case considering you didn't post a full example of code + unit tests, but your mock will throw only when you are passing 6 as parameter. When configuring the behaviour of your mock with when you are telling it to throw only when the validateAndSend method is called with parameter 6.
when(secondService.validateAndSend(6)).thenThrow(...)
In your code you have 5 hardcoded. So that mock will never throw for the code you have, because it's configured to react to an invocation with parameter 6 but the actual code is always invoking it passing 5.
public void sendMessage(){
secondService.validateAndSend(5)
}
If the value passed to the mock is not important you could do something like the following, that will throw no matter what's passed to it:
when(secondService.validateAndSend(any())).thenThrow(BadRequestException.class);
On the other hand, if the value is important and it has to be 5 you could change the configuration of your mock with:
when(secondService.validateAndSend(5)).thenThrow(BadRequestException.class)
I am new to String, SpringBoot.
Can we suppress thrown exception in a method annotated with #AfterThrowing?
I mean when an exception is thrown, it will suppress that and will return a default value on behalf of the invoking method?
Say, I have a controller -
#RestController
public class MyRestController implements IRestController{
#Override
#GetMapping("hello-throw")
public String mustThrowException(#RequestParam(value = "name")final String name) throws RuntimeException {
System.out.println("---> mustThrowException");
if("Bakasur".equals(name)) {
throw new RuntimeException("You are not welcome here!");
}
return name + " : Welcome to the club!!!";
}
}
I have created a #AspectJ, as follows -
#Aspect
#Component
public class MyAspect {
#Pointcut("execution(* com.crsardar.handson.java.springboot.controller.IRestController.*(..))")
public void executionPointcut(){
}
#AfterThrowing(pointcut="executionPointcut()",
throwing="th")
public String afterThrowing(JoinPoint joinPoint, Throwable th){
System.out.println("\n\n\tMyAspect : afterThrowing \n\n");
return "Exception handeled on behalf of you!";
}
}
If I run this & hit a ULR like - http://localhost:8080/hello-throw?name=Bakasur
I will get RuntimeException, but, I want to return a default message like - Exception handeled on behalf of you!, can we do it using #AfterThrowing?
I know it can be done using #Around, but around will be called on every hit of the url, that I do not want
What you want to do is Exception Handling on the controller. You don't need to build it yourself, Spring already supports you with some annotations like #ExceptionHandler and #ControllerAdvice. Best would be to follow this example: https://spring.io/blog/2013/11/01/exception-handling-in-spring-mvc#using-controlleradvice-classes
#ControllerAdvice
class GlobalControllerExceptionHandler {
#ResponseStatus(HttpStatus.CONFLICT) // 409
#ExceptionHandler(DataIntegrityViolationException.class)
public void handleConflict() {
// Nothing to do
}
}
#ControllerAdvice
class GlobalDefaultExceptionHandler {
public static final String DEFAULT_ERROR_VIEW = "error";
#ExceptionHandler(value = Exception.class)
public ModelAndView
defaultErrorHandler(HttpServletRequest req, Exception e) throws Exception {
// If the exception is annotated with #ResponseStatus rethrow it and let
// the framework handle it - like the OrderNotFoundException example
// at the start of this post.
// AnnotationUtils is a Spring Framework utility class.
if (AnnotationUtils.findAnnotation
(e.getClass(), ResponseStatus.class) != null)
throw e;
// Otherwise setup and send the user to a default error-view.
ModelAndView mav = new ModelAndView();
mav.addObject("exception", e);
mav.addObject("url", req.getRequestURL());
mav.setViewName(DEFAULT_ERROR_VIEW);
return mav;
}
}
You should use the fully qualified name of the class before method's name when you're referring to a pointcut. So, you should change #AfterThrowing something like this.
#AfterThrowing(pointcut="packageName.MyAspect.executionPointcut()",
throwing="th")
Please note that packageName is full package name of MyAspect.
I have the following RESTful Services method :
#PostMapping("/ajouterNewField")
public String ajouterField(#Valid #ModelAttribute("field") Fields field, Model model) throws IOException {
fieldDao.save(field);
// SOME CODE
return displayListeChamps( model);
}
The method is working fine and my question is how to handle any error (database not connected ...) or every issue that can happen durring the execution of this RESTful Services method.
You can use #ControllerAdvice
Refer to the code below
#ControllerAdvice
public String NyExceptionHandlerAdvice {
private final Logger logger = ...;
#ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
#ExceptionHandler({MyRunTimeException.class})
public void handleMyRunTimeException(Exception e) {
logger.error("Exception : ", e);
}
return MY_ERROR_STRING;
}
Best Practice is:
You can have your code throw RunTimeExceptions and handle all of them together or separately in handler methods similar to handleMyRunTimeException above.
You can decide what status code your request should return upon exception.
Basically you'll have to a sort of exception handler for any kind of exception your method might throw:
public class FooController{
// ...
#ExceptionHandler({ CustomException1.class, CustomException2.class })
public void handleException() {
//
}
}
Here's a nice article about that: https://www.baeldung.com/exception-handling-for-rest-with-spring
I am trying to log the exception in the spring boot based web service.
So I have used GlobalExceptionHandler
My code :
#ControllerAdvice
#RestController
public class GlobalExceptionHandler {
#ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
#ExceptionHandler(value = Exception.class)
public String handleException(Exception e){
System.out.println("Ankit == "+e.getMessage());
StringWriter errors = new StringWriter();
e.printStackTrace(new PrintWriter(errors));
System.out.println(errors.toString());
return e.getMessage();
}
}
the code is working fine. What I want is exception details. I mean the code where the exception occurs? File name / line ? or do I have to parse the stacktrace? I mean spring boot must have thought something for this?
Using IDE
If you are using any IDE then go to Console Window.
Clear console
Repeat action that causes Exception
Search in Console (CTRL + F) for ERROR
Look for line above(Look for 2-3 lines if you don't find immediate above) the line which contains ERROR. This line has details of Class, Method where Exception has occurred.
Without looking at Console or Logs
If you want to use it in production then, handling atleast known exceptions(like BAD_REQUEST, NOT_FOUND etc.) the way it is done below might be helpful (adding an extra parameter to Exception Class) :
Employee employee = employeeService.getEmployeeById(employeeId);
if (null == employee) {
logger.error("No tenant exists for employeeId:"+employeeId);
throw new ObjectNotFoundException("Emplyee Not Found", this.getClass().getSimpleName();));
}
here this.getClass().getSimpleName(); will be passed as parameter from EmployeeController class. So in ObjectNotFoundException we can add a parameter ClassName and When you handle it in GlobalExceptionHandler, you can do it as it is done below,
#ControllerAdvice
#RestController
public class GlobalExceptionHandler {
#ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
#ExceptionHandler(value = Exception.class)
public String handleException(Exception e){
System.out.println("Ankit == "+e.getMessage());
StringWriter errors = new StringWriter();
e.printStackTrace(new PrintWriter(errors));
String classWithExceptionName = e.getClassName();
// you need to add this above getter method to your Exception Class
System.out.println(errors.toString());
return e.getMessage();
}
}
This is for known common exceptions. We need to add extra parameter(ClassName) to All Custom Exceptions that you are throwing and that might be little extra code but i think that is the way. Hope it helps now.
I want to intercept a bad JSON input and return custom error messages using Dropwizard application. I followed the approach of defining a custom exception mapper as mentioned here : http://gary-rowe.com/agilestack/2012/10/23/how-to-implement-a-runtimeexceptionmapper-for-dropwizard/ . But it did not work for me. This same question has been asked here https://groups.google.com/forum/#!topic/dropwizard-user/r76Ny-pCveA but unanswered.
Any help would be highly appreciated.
My code below and I am registering it in dropwizard as environment.jersey().register(RuntimeExceptionMapper.class);
#Provider
public class RuntimeExceptionMapper implements ExceptionMapper<RuntimeException> {
private static Logger logger = LoggerFactory.getLogger(RuntimeExceptionMapper.class);
#Override
public Response toResponse(RuntimeException runtime) {
logger.error("API invocation failed. Runtime : {}, Message : {}", runtime, runtime.getMessage());
return Response.serverError().type(MediaType.APPLICATION_JSON).entity(new Error()).build();
}
}
Problem 1:
The exception being thrown by Jackson doesn't extends RuntimeException, but it does extend Exception. This doesn't matter though. (See Problem 2)
Problem 2:
DropwizardResourceConfig, registers it's own JsonProcessingExceptionMapper. So you should already see results similar to
{
"message":"Unrecognized field \"field\" (class d.s.h.c.MyClass),..."
}
Now if you want to override this, then you should create a more specific exception mapper. When working with exception mappers the most specific one will be chosen. JsonProcessingException is subclassed by JsonMappingException and JsonProcessingException, so you will want to create an exception mapper for each of these. Then register them. I am not sure how to unregister the Dropwizard JsonProcessingExceptionMapper, otherwise we could just create a mapper for JsonProcessingException, which will save us the hassle of create both.
Update
So you can remove the Dropwizard mapper, if you want, with the following
Set<Object> providers = environment.jersey().getResourceConfig().getSingletons();
Iterator it = providers.iterator();
while (it.hasNext()) {
Object val = it.next();
if (val instanceof JsonProcessingExceptionMapper) {
it.remove();
break;
}
}
Then you are free to use your own mapper, JsonProcessingException