How to wrap the entity data and pass to the spring

Question

I am trying to wrap the entity data with some other information such as requestor info. Right now, I have the following code,

public class EntityController {

    @Autowired
    private EntityValidator entityValidator;

    ...

    @InitBinder("entity")
    protected void initBinder(WebDataBinder binder) {
        binder.addValidators(entityValidator);
    }

}

and my validitor is like

public class EntityValidator implements Validator {

    @Override
    public boolean supports(Class<?> clz) {
        return Entity.class.equals(clz);
    }

    @Override
    public void validate(Object obj, Errors errors) {
        ...
    }

}

For the Object parameter passed into the validate method is the Entity class object now. As I said, I want a customized object with this entity class object wrapped in. Is that possible? If yes, how to do that? Please help. Many thanks.

Answer 1

If I understand correctly, you want the Entity instance to be a member of another class (a customized object with this entity class object wrapped in). How about something like this:

public interface EntityHolder {
  Entity getEntity();
}

Which you can implement (the customized object) in a number of ways:

public class RequestorInfo implements EntityHolder {
  private final long requestorId;
  public Entity getEntity() { ... }
}

public class CustomObject2 implements EntityHolder {
  public Entity getEntity() { ... }
}

And then use the validator like this:

public class EntityValidator implements Validator {

  @Override
  public boolean supports(Class<?> clz) {
    return EntityHolder.class.isAssignableFrom(clz);
  }

  @Override
  public void validate(Object obj, Errors errors) {
    EntityHolder holder = (EntityHolder) obj;
    // validate the entity obtained by holder.getEntity()  
  }

}

Notice the equals was changed to isAssignableFrom in the supports method. This enables you to pass in a subclass of EntityHolder.