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

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

Solution

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

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.