code: func (h *hasOneAssociation) AfterInterface() interface{} {
  	m := h.ownedModel
  	if fieldIsNil(m) {
  		return nil
  	}
  	if m.Kind() == reflect.Ptr {
  		return m.Interface()
  	}
  	if IsZeroOfUnderlyingType(m.Interface()) {
  		return nil
  	}
  
  	return m.Addr().Interface()
  }
docs: // AfterInterface gets the value of the model to create after
  // creating the parent model. It returns nil if its value is
  // not set.