Grails command object data binding

Question

Grails has very good support for binding request parameters to a domain object and it\'s associations. This largely relies on detecting request parameters that end with

Answer 1

Do you actually need to have sub-commands for attributeTypes and productType properties? Any reason you're not using PropertyEditorSupport binding? E.g.:

public class ProductTypeEditor extends PropertyEditorSupport
{
    ProductAdminService productAdminService // inject somewhow
    void setAsText(String s)
    {
        if (s) value = productAdminService.productTypes.find { it.id == s.toLong() }
    }

    public String getAsText()
    {
        value?.id        
    }
}

(and something similar for attributeType object), and register these in a editor registrar:

import java.beans.PropertyEditorSupport
public class CustomEditorRegistrar implements PropertyEditorRegistrar {
    public void registerCustomEditors(PropertyEditorRegistry reg) {
        reg.registerCustomEditor(ProductType, new ProductTypeEditor())
        reg.registerCustomEditor(AttributeType, new AttributeTypeEditor())
    }
}

And register in your resources.groovy:

beans =
{
    customEditorRegistrar(CustomEditorRegistrar)
}

then in your Cmd you just have:

class ProductCommand {
    String name
    List attributeTypes = []
    ProductType productType
}

If you do need actual sub-command associations then I've done something similar to what @Andre Steingress has suggested, in combination with PropertyEditorSupport binding:

// parent cmd
import org.apache.commons.collections.ListUtils
import org.apache.commons.collections.FactoryUtils
public class DefineItemConstraintsCmd implements Serializable
{
    List allItemConstraints = ListUtils.lazyList([], FactoryUtils.instantiateFactory(ItemConstraintsCmd))
    //...
}    
// sub cmd
@Validateable
class ItemConstraintsCmd implements Serializable
{
    Item item // this has an ItemEditor for binding
    //...
}

Hopefully I've not misunderstood what you're trying to achieve :)