Vaadin與SpringBoot

Question

嗨所以我是Vaadin的新手，嘗試創建窗體並綁定到該POJO對象。

...Some declaration 

Binder<User> binder = new Binder<>(User.class); 

@Autowired 
public FormUser(UserRepository userRepository, AuthorityRepository authorityRepository){ 
    this.userRepository = userRepository; 
    this.authorityRepository = authorityRepository; 

    authorities = new ListSelect<>("Authorities", authorityRepository.findAll()); 
    authorities.setItemCaptionGenerator(Authority::getAuthority); 

    //Set items 
    username.setIcon(FontAwesome.USER); 
    password.setIcon(FontAwesome.USER_SECRET); 
    saveButton.addClickListener(e -> { 
     userRepository.save(user); 
    }); 

    setSpacing(true); 
    addComponents(username, password, authorities, saveButton); 
    binder.bindInstanceFields(this); 
} 

當嘗試訪問視圖包含FormUser得到這個錯誤：

java.lang.IllegalStateException: Property type 'java.util.Collection' doesn't match the field type 'java.util.Set< dev.gva.model.Authority >'. Binding should be configured manually using converter.

管理局：

public class Authority{ 
    private Long id; 
    private String authority; 

    getter/setters.. 
} 

用戶：

public class User{ 
    private Long id; 
    private Collection<Authority> authorities; 

    other fields, getters/setters... 
} 

如何寫這個轉換器？由於

Answer 1

而是添加樣板代碼的轉換，你應該使用設置或列表爲User -class內的authorities -attribute。這樣做的一個優點是在authorities中不允許有重複。 設置和之間的區別列表是列表是有序的，可以通過索引訪問。你決定你需要什麼，但是設置可能就夠了。