In Grails, how can I get a ConfigObject of messages.properties for locale?

Question

In Grails, I would like to get a ConfigObject reference to the loaded messages properties file for the current locale. Or some way to easily read in the messages properties (for the current locale) in it's entirety. I want to convert it to JSON and send it back to the client to be used to lookup strings via javascript.

In essence I want to do something like this:

def props = new java.util.Properties()
props.load(... the right message bundle ...);
def messages = new ConfigSlurper().parse(props)
render messages as JSON

I'm assuming there's a more graceful way to do this. The messageSource interface only allows you to get a message for a particular key. I want the entire resource bundle so I can convert it to JSON.

Answer 1

The implementation type of MessageSource is org.codehaus.groovy.grails.context.support.PluginAwareResourceBundleMessageSource. Perhaps there are methods on this class (or one of it's parents), that will allow you to get a reference to the entire set of Properties.

The following looks like it might work (though I haven't tested it):

// Get a reference to the message Source either via dependency injection or looking-up
// the bean in the application context
def messageSource
Properties messages = messageSource.getProperties("messages.properties").properties
// Now convert the Properties instance to JSON using your favorite Java-JSON library

This is not a great solution as the getProperties(filename) method is protected, so you should not be able to call it, but you can because of a bug in Groovy. It also makes some implicit assumptions about the implementation type of mesageSource.

Answer 2

I found a workable solution of just loading the properties directly from the proper messages properties bundle based on the current locale.

It looks like I can just load the file with a path relative to the root of the application. This worked for running locally both with the embedded tomcat and as a war ('grails run-app' and 'grails run-war') but I haven't tested deployed to a container to know if the path will be resolved properly.

Here's my test controller:

import grails.converters.*
import org.springframework.context.i18n.LocaleContextHolder as LCH 

class I18nController {

    def index = {
        def locale = LCH.getLocale().toString();
        def langSuffix = ( locale == "en" ) ? "" : "_${locale}" 
        def props = new java.util.Properties()
        props.load( new FileInputStream( "grails-app/i18n/messages${langSuffix}.properties" ) )
        render ( new ConfigSlurper().parse(props) ) as JSON
    }

}

Can be accessed like:

http://localhost:8080/myapp/i18n
http://localhost:8080/myapp/i18n?lang=es
http://localhost:8080/myapp/i18n?lang=en