i need your help.
I have method for creating entity in RestController, but i can not understand how to use ResponseEntity. I just return ResponseEntity.ok, but it's not correct i think.
I got advice to wrap it into object with data and success fields, but i didn't get it.
#PostMapping()
public ResponseEntity<String> create(#Valid #RequestBody Course course) {
try {
courseService.add(course);
} catch (ServiceException e) {
log.error("Can not create course", e);
}
return ResponseEntity.ok("Course is valid");
}
#PutMapping("/{id}")
public ResponseEntity<String> update(#Valid #RequestBody Course course, #PathVariable("id") int id)
throws ServiceException {
courseService.update(id, course);
return ResponseEntity.ok("Course is valid");
}
You can try this: ResponseEntity<>("Course is valid", HttpStatus.OK)
For more details and guide : https://www.baeldung.com/spring-response-entity
I did something like this:
return new ResponseEntity<>(course, HttpStatus.CREATED);
Related
I'm use the #FeignClient and want to do some logic(like record the exception information) when Feign throw Exception and then reply the result to front end.
I noticed Feign will throw FeignException when connection fail or http status not expect.
So I defined a #ExceptionHandler to caught FeignException after the callback method was invoked.
#ExceptionHandler(value = FeignException.class)
#ResponseBody
public ResponseResult feignException(FeignException exception){
String message = exception.getMessage();
byte[] content = exception.content();
int status = exception.status();
if(content!=null){
String response=new String(content);
message=String.format("%s response message : %s",message,response);
}
log.warn("{} : {} , cause by : {}",exception.getClass().getSimpleName(),message,exception.getCause());
return ResponseResult.fail(HttpStatus.valueOf(status),String.format("9%s00",status),message);
But it can't caught when I set the callback or callbackFactory of #FeignClient.
#FeignClient(url = "${onboardingcase.uri}",name = "OnBoardingCaseService",
fallbackFactory = OnBoardingCaseServiceFallBack.class)
#Component
#Slf4j
public class OnBoardingCaseServiceFallBack implements FallbackFactory<OnBoardingCaseService> {
#Override
public OnBoardingCaseService create(Throwable throwable) {
return new OnBoardingCaseService() {
#Override
public OnBoardingCaseVo query(String coid) {
if(throwable instanceof FeignException){
throw (FeignException)throwable;
}
return null;
}
};
}
}
I noticed because hystrix took over this method.And will catch exception in HystrixInvocationHandler.
try {
Object fallback = HystrixInvocationHandler.this.fallbackFactory.create(this.getExecutionException());
Object result = ((Method)HystrixInvocationHandler.this.fallbackMethodMap.get(method)).invoke(fallback, args);
if (HystrixInvocationHandler.this.isReturnsHystrixCommand(method)) {
return ((HystrixCommand)result).execute();
} else if (HystrixInvocationHandler.this.isReturnsObservable(method)) {
return ((Observable)result).toBlocking().first();
} else if (HystrixInvocationHandler.this.isReturnsSingle(method)) {
return ((Single)result).toObservable().toBlocking().first();
} else if (HystrixInvocationHandler.this.isReturnsCompletable(method)) {
((Completable)result).await();
return null;
} else {
return HystrixInvocationHandler.this.isReturnsCompletableFuture(method) ? ((Future)result).get() : result;
}
} catch (IllegalAccessException var3) {
throw new AssertionError(var3);
} catch (ExecutionException | InvocationTargetException var4) {
throw new AssertionError(var4.getCause());
} catch (InterruptedException var5) {
Thread.currentThread().interrupt();
throw new AssertionError(var5.getCause());
}
So I want to know how can I throw an exception when I using callback / callbackFactory or there is another way to instead callbackFactory to do the "call back"?
Many Thanks
I found a solution to this problem.
public class OnBoardingCaseServiceFallBack implements FallbackFactory<OnBoardingCaseService> {
#Override
public OnBoardingCaseService create(Throwable throwable) {
return new OnBoardingCaseService() {
#Override
public OnBoardingCaseVo query(String coid) {
log.error("OnBoardingCaseService#query fallback , exception",throwable);
if(throwable instanceof FeignException){
throw (FeignException)throwable;
}
return null;
}
};
}
}
And then caught the HystrixRuntimeException and get the cause of exception in ExceptionHandler for get the realException that was wrapped by Hystrix.
#ExceptionHandler(value = HystrixRuntimeException.class)
#ResponseBody
public ResponseResult hystrixRuntimeException(HystrixRuntimeException exception){
Throwable fallbackException = exception.getFallbackException();
Throwable assertError = fallbackException.getCause();
Throwable realException = assertError.getCause();
if(realException instanceof FeignException){
FeignException feignException= (FeignException) realException;
String message = feignException.getMessage();
byte[] content = feignException.content();
int status = feignException.status();
if(content!=null){
String response=new String(content);
message=String.format("%s response message : %s",message,response);
}
return ResponseResult.fail(HttpStatus.valueOf(status),String.format("9%s00",status),message);
}
String message = exception.getMessage();
log.warn("{} : {} , cause by : {}",exception.getClass().getSimpleName(),message,exception.getCause());
return ResponseResult.fail(ResultCode.FAIL.httpStatus(),ResultCode.FAIL.code(),message);
}
But I don't think that's a good way~
I have never done this in fallback, I have implemented custom error decoder(“CustomFeignErrorDecoder”) class and extended feign.codec.ErrorDecoder, every time an error occurs it comes to this class.
In decode function throw a custom exception and catch it in the controller or service layer to show your message to the frontend.
Example:
#Component
public class CustomFeignErrorDecoder implements ErrorDecoder {
#Override
public Exception decode(String methodKey, Response response) {
throw new CustomFeignErrorDecoderException(methodKey +" response status "+ response.status() +" request "+ response.request()+ " method "+ response.request().httpMethod());
}
}
What is the best way to return an error message with ReponseEntity?
Say I have the following method
#Transactional
#RequestMapping(value = "/{id}", method = RequestMethod.GET)
public ResponseEntity<User> getUser(#PathVariable("id") Long id) {
User user = userRepository.findOne(id);
if (user == null) {
return new ResponseEntity<>(HttpStatus.NOT_FOUND);
}
else {
return new ResponseEntity<>(user, HttpStatus.OK);
}
Now what if I want to return an error message to the front end? I can't do the following because the method return type is
ResponseEntity<User>
not
ResponseEntity<String>
so this will not work
if (user == null) {
return new ResponseEntity<>("User does not exist", HttpStatus.NOT_FOUND);
}
I could make the method return type
ResponseEntity<Object>
but that just seems slopy and bad practice. I want to be able to return at least a brief error message that gives some indication of what went wrong to the front end. How is the best way to go about doing this?
Update:
After some digging around I came up with this and it seems to work but curious if it would have a performance impact.
#RequestMapping(value = "/{id}", method = RequestMethod.GET)
public ResponseEntity<?> getUser(#PathVariable("id") Long id) {
User user = userRepository.findOne(id);
if (user == null) {
return new ResponseEntity<>("User not found", HttpStatus.NOT_FOUND);
}
else {
return new ResponseEntity<>(user, HttpStatus.OK);
}
}
I realise you asked specifically about returning the error message using ReponseEntity, but you could also consider using Spring MVCs exception handling to acheive the same outcome:
// Example from the linked Spring article:
#RequestMapping(value="/orders/{id}", method=GET)
public String showOrder(#PathVariable("id") long id, Model model) {
Order order = orderRepository.findOrderById(id);
if (order == null) throw new OrderNotFoundException(id);
model.addAttribute(order);
return "orderDetail";
}
#ResponseStatus(value=HttpStatus.NOT_FOUND, reason="No such Order") // 404
public class OrderNotFoundException extends RuntimeException {
// ...
}
I need to populate my pojo class based on the request param 'type'.
so I have code like
#ModelAttribute
public void getModelObject(HttpServletRequest request, ModelMap modelMap) {
String typeCombo = request.getParameter("type");
System.out.println("typeCombo: " + typeCombo);
if (typeCombo != null) {
if (condition) {
modelMap.addAttribute("modelObj", new ClassB()); //ClassB extends ClassA
} else if (another condition) {
modelMap.addAttribute("modelObj", new ClassC()); //ClassC extends ClassA
} else {
System.out.println("no type found");
}
} else {
System.out.println("typecombo null");
}
}
I use above method to get create correct subclasses which will be used to add / update. The above one works fine in case of "POST" - for creating a record. But for "PUT" request.getParameter("type") always returns null. So for editing, I'm not able to get correct subclasses.
Below are my post and put request mapping:
#RequestMapping(value = "", method = RequestMethod.POST, headers = "Accept=*/*")
#ResponseBody
public String addCredentials(#ModelAttribute("modelObj") Credential credential,
ModelMap modelMap) {
//code
}
#RequestMapping(value = "/edit/{id}", method = RequestMethod.PUT, headers = "Accept=*/*")
#ResponseBody
public Credential editCredential(#ModelAttribute ("modelObj") Credential credential, #PathVariable long id, ModelMap model) {
//code
}
Any help is much appreciated.
Register the filter HttpPutFormContentFilter like this:
<beans:bean id="httpPutFormContentFilter"
class="org.springframework.web.filter.HttpPutFormContentFilter" />
I have this method that tries to get a list of things:
private static IQueryable<Thing> GetThings(int thingsType)
{
try
{
return from thing in entities.thing.Include("thingStuff")
select thing;
}
catch (Exception exception)
{
return new EnumerableQuery<Thing>(?????);
}
}
}
I want to return an empty IQueryable if I can't for whatever reason get the query to run. I don't want to return NULL because that could break the calling code. Is it possible or am I going totally wrong about this?
These answers are good and do work, however I have always felt using Empty and not creating a new List is cleaner:
Enumerable.Empty<Thing>().AsQueryable();
Try the following:
private static IQueryable<Thing> GetThings(int thingsType)
{
IQueryable<Thing> things = new List<Thing>().AsQueryable();
try
{
things = from thing in entities.thing.Include("thingStuff")
select thing;
return things;
}
catch (Exception exception)
{
return things;
}
}
I would add block finally {} and put my return type in that code.
This will take care of the issue by returning the type that your application expects.
private static IQueryable<T> GetThings(int thingsType)
{
IQueryable<T> list = new List<Thing>().AsQueryable();
try
{
list = from thing in entities.thing.Include("thingStuff")
select t;
}
catch (Exception exception)
{
// handle exception here;
}
finally {
return list;
}
}
}
Returning empty IQueryable<>
DbSet.Take(0)
I think this would be tidier:
private static IQueryable<T> GetThings(int thingsType)
{
try
{
return from thing in entities.thing.Include("thingStuff")
select t;
}
catch (Exception exception)
{
// Exception handling code goes here
return new List<Thing>().AsQueryable();
}
}
I have an MVC 2 app that I want all requests to return json. I have overridden a HandleErrorAttribute and an AuthorizeAttribute. My goal is that all errors (even 403 and 404) are returned as json.
Here is my error handler. ExceptionModel is a simple class defining any error returned by my application. The Exception handler is a class that translates the error details into a formatted e-mail and sends it to me.
public class HandleErrorJsonAttribute : System.Web.Mvc.HandleErrorAttribute
{
public override void OnException(ExceptionContext context)
{
context.ExceptionHandled = true;
RaiseErrorSignal(context.Exception);
context.RequestContext.HttpContext.Response.ContentType = "application/json";
JsonSerializer serializer = new JsonSerializer();
serializer.Serialize(context.HttpContext.Response.Output, new ExceptionModel(context.Exception));
}
private static void RaiseErrorSignal(Exception ex)
{
IExceptionHandler handler = Resolve();
handler.HandleError(ex.GetBaseException());
}
private static IExceptionHandler Resolve()
{
return ServiceLocator.Locate<IExceptionHandler>();
}
}
Here is the Exception model for clarification
public class ExceptionModel
{
public int ErrorCode { get; set; }
public string Message { get; set; }
public ExceptionModel() : this(null)
{
}
public ExceptionModel(Exception exception)
{
ErrorCode = 500;
Message = "An unknown error ocurred";
if (exception != null)
{
if (exception is HttpException)
ErrorCode = ((HttpException)exception).GetHttpCode();
Message = exception.Message;
}
}
public ExceptionModel(int errorCode, string message)
{
ErrorCode = errorCode;
Message = message;
}
}
and finally, my custom authorize attribute. I an using forms auth, but I did not want any of the automatic redirection. I simply want the error to show on the screen and stop any further processing.
public class AuthorizeTokenAttribute : System.Web.Mvc.AuthorizeAttribute
{
public bool SuperAdminOnly { get; set; }
protected override bool AuthorizeCore(HttpContextBase httpContext)
{
bool authorized = base.AuthorizeCore(httpContext);
if(!SuperAdminOnly)
return authorized;
if(!authorized)
return authorized;
return SessionHelper.UserIsSuperAdmin(httpContext.User.Identity.Name);
}
protected override void HandleUnauthorizedRequest(System.Web.Mvc.AuthorizationContext filterContext)
{
throw new HttpException(403, "Access Denied");
}
}
This all works great for most errors, but it is missing one thing. I have a controller action like this.
[AuthorizeToken]
[HttpPost]
public JsonResult MyAction()
{
return new JsonResult();
}
It works fine when you submit via post, but on a get I receive an unhandled 404 error.
Server Error in '/' Application.
The resource cannot be found.
Description: HTTP 404. The resource
you are looking for (or one of its
dependencies) could have been removed,
had its name changed, or is
temporarily unavailable. Please
review the following URL and make sure
that it is spelled correctly.
Requested URL: /MyController/MyAction
Version Information: Microsoft .NET
Framework Version:4.0.30319; ASP.NET
Version:4.0.30319.1
This happens on a GET, which is to be expected as default behavior. However, how can I handle for this condition so that I could instead return json like this
{"ErrorCode":404,"Message":"Page Not Found"}
To handle errors personally I prefer the Application_Error event in Global.asax:
protected void Application_Error(object sender, EventArgs e)
{
var exception = Server.GetLastError();
Response.Clear();
Server.ClearError();
var httpException = exception as HttpException;
var routeData = new RouteData();
routeData.Values["controller"] = "Errors";
routeData.Values["action"] = "Index";
routeData.Values["error"] = exception;
IController errorController = new ErrorsController();
errorController.Execute(new RequestContext(new HttpContextWrapper(Context), routeData));
}
and then have an ErrorsController:
public class ErrorsController : Controller
{
public ActionResult Index(Exception exception)
{
var errorCode = 500;
var httpException = exception as HttpException;
if (httpException != null)
{
errorCode = httpException.ErrorCode;
}
return Json(new
{
ErrorCode = errorCode,
Message = exception.Message
}, JsonRequestBehavior.AllowGet);
}
}