Grails data binding with command object

Question

Could anyone explain to me how and which particular classes in grails does the data binding with command objects?

I am seeing some weird behavior in case of JSON post requests. For example, I have nested command objects that are registered with custom property editor. My custom property editor is being used only if I have collection of inner commands ie I am seeing setValue(Object obj) getting called in this case. For example,

class TestCommand
{
  List<InnerCommand> innerCommands = ListUtils.lazyList([], FactoryUtils.instantiateFactory(InnerCommand))
}

But when I have a simple nested command, my property editor does not get called which I dont want. For example,

class TestCommand
{
  InnerCommand cmd = new InnerCommand
}

In this case neither the setValue(Object obj) nor setAsString(String text) of my custom editor is getting called.

I am using post request with JSON input.Please let me know if anyone understands this behavior.

Answer 1

There are two way to implement command object in Grails

1) create command object inside controller 2) create command object inside src/groovy directory

both way must define annotations before class start "@grails.validation.Validateable"

1) type 1 LoginController.groovy

class LoginController{

       def login(){
            LoginCommand loginCommand=new LoginCommand()
            bindData(loginCommand, params)
           if(loginCommand.validate()){
             render 'login success'
           }else{
             render 'invalid user name or password'
           }
       }
    }

@grails.validation.Validateable
class LoginCommand {

        String emailId
        String password

        static constraints = {
        emailId blank:false,nullable:false,email:true
        password blank:false,nullable:false
    }

}

2) type 2 LoginCommand.groovy

@grails.validation.Validateable
class LoginCommand {

    String emailId
    String password

    static constraints = {
        emailId blank:false,nullable:false,email:true
        password blank:false,nullable:false
    }

}

Note: you need to pass 'emailId' and 'password' value from your .gsp page.