how to register a custom json marshaller in grails

Question

I am trying to register a custom json marshaller like this

 JSON.createNamedConfig("dynamic",{ 
            def m = new CustomJSONSerializer()
            JSON.registerObjectMarshaller(Idf, 1, { instance, converter -> m.marshalObject(instance, converter) }) 
            })

and then using it like this

    JSON.use("dynamic"){
            render inventionList as JSON
            }

but I am not sure if my custom serializer is being used because when I am debugging control never goes to marshalObject function of my custom serializer

My custom serializer is as follows

import grails.converters.deep.JSON
import java.beans.PropertyDescriptor
import java.lang.reflect.Field
import java.lang.reflect.Method
import org.codehaus.groovy.grails.web.converters.exceptions.ConverterException
import org.codehaus.groovy.grails.web.converters.marshaller.json.GroovyBeanMarshaller
import org.codehaus.groovy.grails.web.json.JSONWriter

class CustomJSONSerializer extends GroovyBeanMarshaller{
    public boolean supports(Object object) {
        return object instanceof GroovyObject;
    }

    public void marshalObject(Object o, JSON json) throws ConverterException {
        JSONWriter writer = json.getWriter();
        println 'properties '+BeanUtils.getPropertyDescriptors(o.getClass())
        for(PropertyDescriptor property:BeanUtils.getProperyDescriptors(o.getClass())){
                println 'property '+property.getName()
            }
        try {
            writer.object();
            for (PropertyDescriptor property : BeanUtils.getPropertyDescriptors(o.getClass())) {
                String name = property.getName();
                Method readMethod = property.getReadMethod();
                if (readMethod != null && !(name.equals("metaClass")) && readMethod.getName()!='getSpringSecurityService') {
                    Object value = readMethod.invoke(o, (Object[]) null);
                    writer.key(name);
                    json.convertAnother(value);
                }
            }
            for (Field field : o.getClass().getDeclaredFields()) {
                int modifiers = field.getModifiers();
                if (Modifier.isPublic(modifiers) && !(Modifier.isStatic(modifiers) || Modifier.isTransient(modifiers))) {
                    writer.key(field.getName());
                    json.convertAnother(field.get(o));
                }
            }
            writer.endObject();
        }
        catch (ConverterException ce) {
            throw ce;
        }
        catch (Exception e) {
            throw new ConverterException("Error converting Bean with class " + o.getClass().getName(), e);
        }
    }


}

Is it possible to debug the serializer? If not then how can I exclude a property from serialization? There's some property which throws exception during serialization.

Solution 1

this is what i do for custom JSON marshaling in the Bootstrap init closure:

def init = {servletContext ->
    grailsApplication.domainClasses.each {domainClass ->
        domainClass.metaClass.part = {m ->
            def map = [:]
            if (m.'include') {
                m.'include'.each {
                    map[it] = delegate."${it}"
                }
            } else if (m.'except') {
                m.'except'.addAll excludedProps
                def props = domainClass.persistentProperties.findAll {
                    !(it.name in m.'except')
                }
                props.each {
                    map['id'] = delegate.id
                    map[it.name] = delegate."${it.name}"
                }
            }
            return map
        }



    }
    JSON.registerObjectMarshaller(Date) {
        return it?.format("dd.MM.yyyy")
    }
    JSON.registerObjectMarshaller(User) {
        def returnArray = [:]
        returnArray['username'] = it.username
        returnArray['userRealName'] = it.userRealName 
        returnArray['email'] = it.email
        return returnArray
    }
    JSON.registerObjectMarshaller(Role) {
        def returnArray = [:]
        returnArray['authority'] = it.authority
        return returnArray
    }
     JSON.registerObjectMarshaller(Person) {
        return it.part(except: ['fieldX', 'fieldY'])
    }}

you see that i have custom marshallers for the Date, Use, Person, and Role Class

Solution 2

I found this post while trying to find out a proper way for the marshaller registering. The biggest difference compared to Nils' answer is that this solution leaves BootStrap.groovy intact, which is nice.

http://compiledammit.com/2012/08/16/custom-json-marshalling-in-grails-done-right/

Comments

[cdeszaq]

The article you linked to is a much better, cleaner approach. To help deal with link rot, please consider quoting the most relevant bits of the article here in your answer.

[adeady]

site appears to be down these days.