Example ExposedGSON

ExposedGSON-withVersion.groovy

package com.reachlocal.product.gson

import com.google.gson.GsonBuilder
import grails.plugin.gson.converters.GSON
import org.codehaus.groovy.grails.commons.ApplicationHolder

class ExposedGSON extends GSON {

  @Lazy
	private GsonBuilder gsonBuilder = {
		def applicationContext = ApplicationHolder.application.mainContext
		applicationContext.getBean('gsonBuilder', GsonBuilder)
	}()

	private String version = null

	private target

	ExposedGSON(def version = null) {
		this.version = version
	}

	@Override
	void setTarget(target){
		super.setTarget(target)
		this.target = target
	}

	@Override
	void render(Writer out) {
		try {
			def builder = gsonBuilder
			if (version && version.isDouble()) {
				builder = builder.setVersion(version as double)
			}
			builder.excludeFieldsWithoutExposeAnnotation().create().toJson(target, out)
		} finally {
			out.flush()
			out.close()
		}
	}
}

ExposedGSON.groovy

package com.example.gson
 
import com.google.gson.GsonBuilder
import grails.plugin.gson.converters.GSON
import org.codehaus.groovy.grails.commons.ApplicationHolder
 
class ExposedGSON extends GSON {
 
  @Lazy
	private GsonBuilder gsonBuilder = {
		def applicationContext = ApplicationHolder.application.mainContext
		applicationContext.getBean('gsonBuilder', GsonBuilder)
	}()
 
 
	private target
 
	ExposedGSON() {}
 
	ExposedGSON(target) {
		setTarget(target)
	}
 
	@Override
	void setTarget(target){
		super.setTarget(target)
		this.target = target
	}
 
	@Override
	void render(Writer out) {
		try {
			gsonBuilder.excludeFieldsWithoutExposeAnnotation().create().toJson(target, out)
		} finally {
			out.flush()
			out.close()
		}
	}
}

I was thinking that rather than needing to change the syntax you use to convert to JSON you could just register a variant of the GrailsDomainSerializer class in the application context. Since that can be done on a class-by-class basis it would allow for using the @Expose style with some classes and the regular style with others.