Grails / Groovy向现有Java类添加属性，而在尝试使用JSON转换器进行序列化时丢失它们？

Question

i am wondering what i am missing in adding dynamic properties to a java class and trying to render that class using the JSON converter. I have a pure java pojo and i am adding a dynamic property to it using:

// adding property
ResetRequest.metaClass.targetIp = "192.168.0.1"
// creating object
ResetRequest obj = new ResetRequest()
// printing the properties
println obj.properties

When printing the properties the object has a additional property called 'targetIp' so all seems ok, but when i try to render the object as JSON the added property is not in the JSON string.

Any suggestion what i am missing.

Answer 1

I think the JSON conversion in grails does not pick up dynamically added properties.

Maybe you should register your own object marshaller for the class in question?

In Bootstrap:

    def init = {servletContext ->
        JSON.registerObjectMarshaller(ResetRequest) {req->
            [
                targetIp:req.targetIp
                //etc 
            ]
    }

UPDATE This link shows how you can inherit from the default Marshaller and add your own logic to marshall specific fields:

http://grails4you.com/2012/04/restful-api-for-grails-domains/

Answer 2

You should register custom property in Bootstrap like

def init = { servletContext ->
  ResetRequest.metaClass.targetIp = {req ->
    return "192.168.0.1";   
  } 
}