Validate nested domain class instance in command object - validation

Question

I try to validate a nested domain class instance on a command object.
Having the following command object
package demo
import grails.databinding.BindingFormat
class SaveEventCommand {
#BindingFormat('yyyy-MM-dd')
Date date
Refreshment refreshment
static constraints = {
date validator: { date -> date > new Date() + 3}
refreshment nullable: true
}
}
And having the following domain class with its own constraints
package demo
class Refreshment {
String food
String drink
Integer quantity
static constraints = {
food inList: ['food1', 'food2', 'food3']
drink nullable: true, inList: ['drink1', 'drink2', 'drink3']
quantity: min: 1
}
}
I need when refreshment is not nullable the command object validates the date property and check the corresponding restrictions in refreshment instance
For now try with this code in the controller:
def save(SaveEventCommand command) {
if (command.hasErrors() || !command.refreshment.validate()) {
respond ([errors: command.errors], view: 'create')
return
}
// Store logic goes here
}
Here through !command.refreshment.validate() I try to validate the refresh instance but I get the result that there are no errors, even when passing data that is not correct.
Thank you any guide and thank you for your time

Answer 1

I typically just include some code that will use a custom validator to kick off validation for any property that is composed of another command object. For example:
thePropertyInQuestion(nullable: true, validator: {val, obj, err ->
if (val == null) return
if (!val.validate()) {
val.errors.allErrors.each { e ->
err.rejectValue(
"thePropertyInQuestion.${e.arguments[0]}",
"${e.objectName}.${e.arguments[0]}.${e.code}",
e.arguments,
"${e.objectName}.${e.arguments[0]}.${e.code}"
)
}
}
})
This way it's pretty clear that I want validation to occur. Plus it moves all the errors up into the root errors collection which makes things super easy for me.

Answer 2

Two things I could think of:
Implement grails.validation.Validateable on your command object
What happens when you provide an invalid date? Can you see errors while validating?