Grails - Change locale behavior to use dash instead of underscore

Question

I'm writing a Grails application that get's it's locale from a 3rd party like so:

my.app.com?lang=en-US since Grails uses en_US it throws the exception Error intercepting locale change: Locale part "en-US" contains invalid characters

How can I intercept the request prior to PageFragmentCachingFilter, in order to fix the locale code?

Is there a better approach?

Answer 1

One way to override the default behavior is to register a CustomLocaleChangeInterceptor as a bean in resources.groovy as

beans = {
    localeChangeInterceptor(your.package.CustomLocaleChangeInterceptor) {
        paramName = "lang"
    }
}

GIST
The idea is to override the default localeChangeInterceptor which is the default interceptor in i18n grails plugin in order to take care of the hyphenated locale string in the request url parameter. Main logic to look at in the custom locale interceptor is:

try {
        // choose first if multiple specified
        if (localeParam.getClass().isArray()) {
            localeParam = ((Object[])localeParam)[0]
        }

        //If locale hyphenated, then change to underscore
        if(localeParam.toString()?.contains('-')){
            localeParam = StringUtils.replace(localeParam.toString(), "-", "_")
        }

        def localeResolver = RequestContextUtils.getLocaleResolver(request)
        def localeEditor = new LocaleEditor()
        localeEditor.setAsText localeParam.toString()
        localeResolver?.setLocale request, response, (Locale)localeEditor.value
        return true
    }
    catch (Exception e) {
        return true
    }