The issue is with the use of default JSON converter. Here are your options:
1. Default - all fields, shallow associations
a. render blah as JSON
2. Global deep converter - change all JSON converters to use deep association traversal
a. grails.converters.json.default.deep = true
3. Named config marshaller using provided or custom converters
a. JSON.createNamedConfig('deep'){
it.registerObjectMarshaller( new DeepDomainClassMarshaller(...) )
}
b. JSON.use('deep'){
render blah as JSON
}
4. Custom Class specific closure marshaller
a. JSON.registerObjectMarshaller(MyClass){ return map of properties}
b. render myClassInstance as JSON
5. Custom controller based closure to generate a map of properties
a. convert(object){
return map of properties
}
b. render convert(blah) as JSON
You are currently using Option 1, which is default.
The simplest you can do is use Option 2 to set global deep converter, but be aware this effects ALL domain classes in your app. Which means that if you have a large tree of associations culminating in a top level object and you try to convert a list of those top level objects the deep converter will execute all of the queries to fetch all of the associated objects and their associated objects in turn. – You could load an entire database in one shot 🙂 Be careful.