java - Wicket AutoCompleteTextField 模型转换

Question

看起来自动完成文本字段的模型对象是一个字符串，即使它应该是一个员工，导致无法从字符串转换为员工的异常。为什么？如何解决？

        final DefaultCssAutocompleteTextField<Employee> field = new DefaultCssAutocompleteTextField<Employee>("field", new Model<Employee>(model.getObject().getMatch().getSupervisor())) {
            @Override
            protected Iterator<Employee> getChoices(String input) {
                if (Strings.isEmpty(input)){
                    List<Employee> emptyList = Collections.emptyList();
                    return emptyList.iterator();
                }
                return supervisorDao.getAutoCompleteCapableSupervisors(input, 6).iterator();
            }
        };

        form.add(field);

        field.add(new AjaxFormSubmitBehavior(form, "onchange") {
            @Override
            protected void onSubmit(AjaxRequestTarget target) {

                //this generates an exception: cant cast from string to employee. why? and how can it be fixed?
                Employee e = supervisorService.findOne(field.getModelObject().getId());

                //do some stuff with the employee and some components

            }

            @Override
            protected void onError(AjaxRequestTarget target) {
                //do nothing
            }
        });

Answer 1

AutoCompleteTextfield 的 javadoc 说:

To convert input back into a non-String type you will have to provide a custom IConverter, either by overriding #getConverter(Class) or by setting a suitable IConverter on the application's ConverterLocator.