What's the simplest way to define a transition that switches the locale and returns to the current view-state? - spring-webflow

Question

We do have the LocaleChangeInterceptor configured if that helps.
(Originally posted to http://forum.springsource.org/showthread.php?123391-Transition-to-set-locale )

Answer 1

Better would be to use existing components. Here is snippet of Spring WebFlow configured to use "LocaleChangeInterceptor":
#Bean
public FlowHandlerMapping flowHandlerMapping(FlowDefinitionRegistry flowDefinitionRegistry) {
FlowHandlerMapping handlerMapping = new FlowHandlerMapping();
handlerMapping.setInterceptors(new Object[] { localeChangeInterceptor() });
// ... other configuration
return handlerMapping;
}
/**
* #category locale_switcher
*/
#Bean
public SessionLocaleResolver localeResolver() {
SessionLocaleResolver localeResolver = new SessionLocaleResolver();
localeResolver.setDefaultLocale(Locale.ENGLISH);
return localeResolver;
}
/**
* #category locale_switcher
*/
#Bean
public LocaleChangeInterceptor localeChangeInterceptor() {
LocaleChangeInterceptor localeChangeInterceptor = new LocaleChangeInterceptor();
localeChangeInterceptor.setParamName("lang");
return localeChangeInterceptor;
}
How it works:
http://localhost:8080/myflow?execution=e1s1&lang=en

Answer 2

This is not what I was seeking, but it's the only thing I found to do. That is, I created an action method to call from the transition:
<transition on="switchLanguage" validate="false">
<evaluate expression="myAction.switchLanguage"/>
</transition>
And, specifically in this case for an Action class that extends MultiAction:
public Event switchLanguage(RequestContext context)
{
// get the "other" locale string itself from the current locale's resource bundle
Locale locale = context.getExternalContext().getLocale();
MessageSource ms = context.getActiveFlow().getApplicationContext();
String newLocaleString = ms.getMessage("lang.other", null, locale);
HttpServletRequest req = (HttpServletRequest) context.getExternalContext().getNativeRequest();
HttpServletResponse res = (HttpServletResponse) context.getExternalContext().getNativeResponse();
LocaleResolver localeResolver = RequestContextUtils.getLocaleResolver(req);
localeResolver.setLocale(req, res, StringUtils.parseLocaleString(newLocaleString));
return success();
}
Where, in my case, I only have to support two languages, so I define in my two messages.properties and messages_es.properties files, the property:
lang.other=es
or
lang.other=en
For other Action class approaches, return whatever you need to to indicate no failures, to either return to the same state again, or to transition to a new state, as desired.
See https://docs.spring.io/spring-webflow/docs/2.5.1.RELEASE/reference/html/views.html#transition-actions
If the transition action invokes a plain Java method, the invoked method may return a boolean whose value, true or false, indicates whether the transition should take place or be prevented from executing. A method may also return a String where the literal values "success", "yes", or "true" indicate the transition should occur, and any other value means the opposite.