I have this enum :
public enum SortEnum {
asc, desc;
}
That I want to use as a parameter of a rest request :
@RequestMapping(value = "/events", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public List<Event> getEvents(@RequestParam(name = "sort", required = false) SortEnum sort) {
It works fine when I send these requests
/events
/events?sort=asc
/events?sort=desc
But when I send :
/events?sort=somethingElse
I get a 500 response and this message in the console :
2016-09-29 17:20:51.600 DEBUG 5104 --- [ XNIO-2 task-6] com.myApp.aop.logging.LoggingAspect : Enter: com.myApp.web.rest.errors.ExceptionTranslator.processRuntimeException() with argument[s] = [org.springframework.web.method.annotation.MethodArgumentTypeMismatchException: Failed to convert value of type [java.lang.String] to required type [com.myApp.common.SortEnum]; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [@org.springframework.web.bind.annotation.RequestParam com.myApp.common.SortEnum] for value 'somethingElse'; nested exception is java.lang.IllegalArgumentException: No enum constant com.myApp.common.SortEnum.somethingElse]
2016-09-29 17:20:51.600 DEBUG 5104 --- [ XNIO-2 task-6] com.myApp.aop.logging.LoggingAspect : Exit: com.myApp.web.rest.errors.ExceptionTranslator.processRuntimeException() with result = <500 Internal Server Error,com.myApp.web.rest.errors.ErrorVM@1e3343c9,{}>
2016-09-29 17:20:51.601 WARN 5104 --- [ XNIO-2 task-6] .m.m.a.ExceptionHandlerExceptionResolver : Resolved exception caused by Handler execution: org.springframework.web.method.annotation.MethodArgumentTypeMismatchException: Failed to convert value of type [java.lang.String] to required type [com.myApp.common.SortEnum]; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [@org.springframework.web.bind.annotation.RequestParam com.myApp.common.SortEnum] for value 'somethingElse'; nested exception is java.lang.IllegalArgumentException: No enum constant com.myApp.common.SortEnum.somethingElse
Is there a way to prevent spring from throwing these exceptions and set the enum to null ?
EDIT
The Strelok's accepted answer works. However, I decided to deal with handling the MethodArgumentTypeMismatchException.
@ControllerAdvice
public class ExceptionTranslator {
@ExceptionHandler(MethodArgumentTypeMismatchException.class)
@ResponseBody
public ResponseEntity<Object> handleMethodArgumentTypeMismatchException(MethodArgumentTypeMismatchException e) {
Class<?> type = e.getRequiredType();
String message;
if(type.isEnum()){
message = "The parameter " + e.getName() + " must have a value among : " + StringUtils.join(type.getEnumConstants(), ", ");
}
else{
message = "The parameter " + e.getName() + " must be of type " + type.getTypeName();
}
return buildResponse(HttpStatus.UNPROCESSABLE_ENTITY, message);
}
You can create a custom converter that will return null instead of an exception when an invalid value is supplied.
Something like this:
@Configuration
public class MyConfig extends WebMvcConfigurationSupport {
@Override
public FormattingConversionService mvcConversionService() {
FormattingConversionService f = super.mvcConversionService();
f.addConverter(new MyCustomEnumConverter());
return f;
}
}
And a simple converter might look like this:
public class MyCustomEnumConverter implements Converter<String, SortEnum> {
@Override
public SortEnum convert(String source) {
try {
return SortEnum.valueOf(source);
} catch(Exception e) {
return null; // or SortEnum.asc
}
}
}
you need to do the following
@InitBinder
public void initBinder(WebDataBinder dataBinder) {
dataBinder.registerCustomEditor(YourEnum.class, new YourEnumConverter());
}
refer the following : https://machiel.me/post/java-enums-as-request-parameters-in-spring-4/
If you are using Spring Boot, this is the reason that you should not use WebMvcConfigurationSupport.
The best practice, you should implement interface org.springframework.core.convert.converter.Converter, and with annotation @Component. Then Spring Boot will auto load all Converter's bean. Spring Boot code
@Component
public class GenderEnumConverter implements Converter<String, GenderEnum> {
@Override
public GenderEnum convert(String value) {
return GenderEnum.of(Integer.valueOf(value));
}
}
The answers provided so far are not complete. Here is an answer example step-by-step that worked for me:-
1st Define the enum in your endpoint signature(subscription type).
Example:
public ResponseEntity v1_getSubscriptions(@PathVariable String agencyCode,
@RequestParam(value = "uwcompany", required = false) String uwCompany,
@RequestParam(value = "subscriptiontype", required = false) SubscriptionType subscriptionType,
@RequestParam(value = "alert", required = false) String alert,
2nd Define a custom property editor that will be used to translate from String to enum:
import java.beans.PropertyEditorSupport;
public class SubscriptionTypeEditor extends PropertyEditorSupport {
public void setAsText(String text) {
try {
setValue(SubscriptionType.valueOf(text.toUpperCase()));
} catch (Exception ex) {
setValue(null);
}
}
}
3rd Register the property editor with the controller:
@InitBinder ("subscriptiontype")
public void initBinder(WebDataBinder dataBinder) {
dataBinder.registerCustomEditor(SubscriptionType.class, new SubscriptionTypeEditor());
}
Translations from string to enum should happen perfectly now.
you can use String instead of SortEnum param
@RequestParam(name = "sort", required = false) String sort
and convert it using
SortEnum se;
try {
se = SortEnum.valueOf(source);
} catch(IllegalArgumentException e) {
se = null;
}
inside of getEvents(...) endpoint method losing elegance but gaining more control over conversion and possible error handling.
来源：https://stackoverflow.com/questions/39774427/springs-requestparam-with-enum