Grails - Field error disappears from parent class - validation

Question

I have the following problem:
I have a domain class called customer, with a field discount embedded.
class Customer {
...
String username
Discount discount
static constraints = { ... }
}
class Discount {
Integer item1
Integer item2
static constraints = { item1 min:1, max:100, nullable:true }
}
I have a controller, where a customer's data can be modified. The code goes something like this:
def edit() {
Customer c = Customer.findByUsername(params.userName)
if(request.method != 'GET'){
bindData(c, params)
if(c.validate()) {
//save the result
}
}
println c.dump()//1
model:[customer:c]
}
Then in the edit.gsp I put the following code:
${customer.dump()}//2
${customer.discount.dump()}
Now my problem is, if I have a validation error, for example the user enters 123 for item1, I get the appropriate errors object which says that Customer bean has 1 field error on field discount.item1 when I call println c.dump()//1
In the edit.gsp on the other hand, the customer bean doesn't have any field errors but customer.discount has the mentioned error. This is a big inconvenience, because I want to render errors next to the fields like so:
<g:renderErrors bean="${customer}" field="discount.item1"/>
But the customer bean doesn't have any errors, just the discount bean (therefore I don't get any errors rendered).
Has this problem occured to any of you ?

Answer 1

It seems that #Validatable classes use functionality of spring framework's AbstractBindingResult, which doesn't support this usage (as far as I can tell).
However I was able to create a workaround, which could be used as a taglib to achieve the same effect:
Given two validateable classes
#Validateable
class TestA {
TestB b
static constraints = {
b validator: {
it.validate()
}
}
}
#Validateable
class TestB {
int c
static constraints = {
c min: 100
}
}
One can simply resolve the bean and the attribute and delegate the rendering to the existing taglib.
import test.*
import org.codehaus.groovy.grails.plugins.web.taglib.*
ValidationTagLib validationTagLib = ctx.getBean(ValidationTagLib)
renderErrorsWithNestedFields = { attrs, body ->
def modifiedAttrs = attrs
String[] path = attrs?.field?.split('\\.')
if(path?.size() > 1) {
Object resolvedBean
resolvedBean = attrs.bean
path[0..-2].each {
//Some error handling would not hurt, but this is just a proof of concept
resolvedBean = resolvedBean[it]
}
modifiedAttrs = new HashMap(attrs)
modifiedAttrs.bean = resolvedBean
modifiedAttrs.field = path.last()
}
validationTagLib.renderErrors (modifiedAttrs, null)
}
TestA a = new TestA(b:new TestB(c:3))
a.validate()
renderErrorsWithNestedFields([bean:a, field:'b.c'], null)
And this should render an error for violating the min constraint on c.