Apache Wicket：在表单验证器中注入依赖项（使用Guice） [英] Apache Wicket: Injecting dependencies in form validators (using Guice)

问题描述

（这基本上是对 。）

我需要使用我的表单验证器之一访问数据库服务层（以确保注册新用户时电子邮件尚未被接收） ）。

I need to access the DB service layer in one of my form validators (to make sure the email is not already taken when registering a new user).

我尝试了以下操作（为简便起见，省略了一些输入字段）：

I tried the following (some input-fields omitted for brevity):

public class RegistrationPage extends WebPage {

    @Inject
    private UserService userService;

    public RegistrationPage() {

        add(new FeedbackPanel("feedback"));

        TextField<String> email = new TextField<String>("email", Model.of(""));

        ...

        email.add(new IValidator<String>() {

            @Override
            public void validate(IValidatable<String> validatable) {

                String email = validatable.getValue();

                if (userService.findUserByEmail(email) != null) {

                    // report error...

                }
            }
        });

        Form<?> form = new Form<Void>("registrationForm") { ... };

        form.add(email);
        add(form);
    }
}

不幸的是，这可能会导致

This can unfortunately result in a

java.lang.IllegalStateException: EntityManager is closed

我怀疑这个问题是由于我使用的是开放会话视图，并且多个表单提交跨越了多个请求。 userService 为第一个请求注入，并（非法）在后续请求中重用。 （如果验证失败，并且用户尝试再次提交表单，则会提交多个表单。）

I suspect that the problem is due to the fact that I'm using open-session-in-view and that multiple form-submissions span over several requests. The userService is injected for the first request and (illegally) reused in subsequent requests. (Multiple form-submissions happen if the validation fails and the user attempts to submit the form again.)

解决此问题的最佳方法是什么？与我解决上一个问题的方法相同，类似的问题？在这种情况下，无疑会变得更加混乱。

What is the best way to solve this? The same way as I solved the previous, similar problem? It will undoubtedly get messier in this case.

推荐答案

您需要和检票口使用不同的生命周期。

There is a bit different lifecycle that you want and that wicket uses.

首先考虑一下，了解Wicket组件的实例化和注入：

First think first, understand Wicket component instantion and injection:

1. 实例组件


2. 调用注入器-
   IComponentInstantionListener.onInstantiation（组件组件）


3. 注入带注释的字段


4. 使用组件（呈现等）


5. 下一个请求-将相同的组件与注入的字段一起使用

1. Instance the component
2. Invoke injector - IComponentInstantionListener.onInstantiation(Component component)
3. Inject annotated field
4. Use component (render, etc.)
5. Next request(s) - use the same component with injected fields

该怎么办？
使用注入到字段中的代理类。调用代理类时，它将使用当前的bean。

What to do? Use a proxy class that is injected into field(s). When the proxy class is invoked it ever uses the current bean.

请参见 http://ci.apache.org/projects/wicket/apidocs/6.0.x/org/apache/wicket/spring/injection/annot/SpringComponentInjector.html

请参见
AnnotProxyFieldValueFactory，位于 http://ci.apache.org/projects/wicket/apidocs/6.0.x/org/apache/wicket/spring /injection/annot/AnnotProxyFieldValueFactory.html

即使您必须编写自己的实现或使用Wicket Contrib或Wicket Stuff。

Even you have to write your own implementation or look to Wicket Contrib or Wicket Stuff.

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