Custom Binding Required for SpringMVC Form Field

Question

I ran into the following SpringMVC issue: there is a domain object which uses a certain Address sub-object, but the getters/setters have to be tweaked to use a different Address object via conversion. This is an architectural requirement.

public class DomainObj {
    protected DomainObj.Address address;

    public anotherpackage.new.Address getAddress()
    {
       return convertFrom(address);
    }

    public void setAddress (anotherpackage.new.Address value)
    {
        this.address = convertTo(value);
    }

}

// Internal Address object, old, #1
public static class Address {
     protected String street1;
     protected String street2;
     // etc., getters/setters
}

Now, in the JSP, I bind an Input Text Field to the new Address object (the result of conversions) that's what we have to deal with. In this new 2nd Address object (anotherpackage.new.Address), there is a field e.g. "addressLine1", which is different from the old object's "Street1":

<form:input path="topObject.address.addressLine1" />

My problem is that the setter, setAddress(), never gets called in this case for binding (verified in the Debugger). Any solutions to this?

This is not a business requirement, unless your business users are also programmers and they 'require' you to do this specific thing (which doesn't sound likely). Business requirements come in the form of 'as a {business person} i want {to achieve a business related goal} so that {benefits}', and they should not really talk about computers and systems. You may mean that this is an architectural requirement, which is a totally different thing. — Software Engineer, Oct 30 '15 at 18:01
Just to provide an update on this, we managed to get a workaround using JAXB's @XmlJavaTypeAdapter(Address.class). This provided the adapter ont he JAXB domain object side. thanks again — gene b., Oct 30 '15 at 20:03

score 2 · Accepted Answer · edited May 23 '17 at 12:14

Your options are:

a) do not bind directly to the business object b) configure a binder to do the conversion to your domain object

Discussion:

Usually in enterprise class software we don't want to bind directly to the business objects -- which are usually entities (in the context of jpa). This is because session handling is a bee-otch. Usually we code against DTOs, and when one is received from the front-end we read the appropriate object from the repository (ORM) layer, update it, and save it back again (I've only described updates because they're the hardest, but a similar model works for everything).

However, spring mvc binders offer a way of binding anything to anything. They're a bit complicated and it'll take too long to explain here, but the docs are in the spring documentation and you want to be looing at converters and a conversion service. There are SO Q/A's on this topic, for example...

Added it as the last sentence in the answer – Software Engineer Oct 30 '15 at 18:11 — Software Engineer, Oct 30 '15 at 18:11

Custom Binding Required for SpringMVC Form Field

1 Answers1