当新记录添加到数据库时，更新vaadin网格

Question

我想将元素添加到数据库中的表中，并用新数据更新网格(可能我应该直接在UI上将记录添加到表中，但不管怎样(。

我的grid组件看起来像这个

@SpringComponent
public class PlayersGrid extends Grid<Player> {
@PostConstruct
public void afterInit() {
addColumn(Player::getId).setHeader("ID");
addColumn(Player::getName).setHeader("Name");
addColumn(Player::getCharacterClass).setHeader("Class");
addColumn(Player::getLevel).setHeader("Level");
}
public class GridContentObserver implements ContentObserver {
@Override
public void refreshContent() {
PlayersGrid.this.getDataProvider().refreshAll();
}
}
}

我通过看起来像这个的表单添加players

@SpringComponent
public class CharacterCreationForm extends FormLayout {
private static final Logger LOGGER = LoggerFactory.getLogger(CharacterCreationForm.class);
private List<ContentObserver> boundObservers = new ArrayList<>();
private TextField name;
private TextField characterClass;
private TextField level;
@Autowired
private PlayerRepository repository;
@PostConstruct
public void create() {
name = new TextField();
characterClass = new TextField();
level = new TextField();
addFormItem(name, "Name");
addFormItem(characterClass, "Class");
addFormItem(level, "Level");
Binder<Player> binder = new Binder<>(Player.class);
binder
.forField(level)
.withConverter(new StringToIntegerConverter(0, ""))
.bind(Player::getLevel, Player::setLevel);
binder.bindInstanceFields(this);
Button button = new Button("Save");
button.addClickListener(buttonClickEvent -> {
try {
Player newPlayer = new Player();
binder.writeBean(newPlayer);
LOGGER.info("Attempt to write object: {}", newPlayer);
repository.save(newPlayer);
// notify observers
boundObservers.forEach(ContentObserver::refreshContent);
} catch (ValidationException e) {
e.printStackTrace();
}
});
add(button);
}
public void addObserver(ContentObserver observer) {
boundObservers.add(observer);
}
}

我在应用程序中的主视图看起来像这个

public MainView(PlayerRepository repository, PlayersGrid grid, CharacterCreationForm form) {
form.addObserver(grid.new GridContentObserver());
form.setWidth("30%");
// find the way to set items in the component
grid.setItems(repository.findAll());
HorizontalLayout horizontalLayout = new HorizontalLayout();
horizontalLayout.add(form);
VerticalLayout verticalLayout = new VerticalLayout();
verticalLayout.add(grid, form);
verticalLayout.setHeight("100%");
add(verticalLayout);
setClassName("main-layout");
}

在启动时，我将所有存储的播放器都放在了网格中。但当我使用表单保存新记录时，它会在数据库中添加新记录，但不会更新网格。

怎么了？

Answer 1

尝试以下更改，我认为这些更改将使代码更加清晰，并解决ContentObserver 的问题

(没有运行代码，所以我不确定编译问题！(

更改1:PlayersGrid实现了ContentObserver，而不是内部类

@SpringComponent
public class PlayersGrid extends Grid<Player> implements ContentObserver {
@PostConstruct
public void afterInit() {
addColumn(Player::getId).setHeader("ID");
addColumn(Player::getName).setHeader("Name");
addColumn(Player::getCharacterClass).setHeader("Class");
addColumn(Player::getLevel).setHeader("Level");
}
@Override
public void refreshContent() {
this.getDataProvider().refreshAll();
}
}

更改2:boundObservers.forEach

@SpringComponent
public class CharacterCreationForm extends FormLayout {
private static final Logger LOGGER = 
LoggerFactory.getLogger(CharacterCreationForm.class);
private List<ContentObserver> boundObservers = new ArrayList<>();
private TextField name;
private TextField characterClass;
private TextField level;
@Autowired
private PlayerRepository repository;
@PostConstruct
public void create() {
name = new TextField();
characterClass = new TextField();
level = new TextField();
addFormItem(name, "Name");
addFormItem(characterClass, "Class");
addFormItem(level, "Level");
Binder<Player> binder = new Binder<>(Player.class);
binder
.forField(level)
.withConverter(new StringToIntegerConverter(0, ""))
.bind(Player::getLevel, Player::setLevel);
binder.bindInstanceFields(this);
Button button = new Button("Save");
button.addClickListener(buttonClickEvent -> {
try {
Player newPlayer = new Player();
binder.writeBean(newPlayer);
LOGGER.info("Attempt to write object: {}", newPlayer);
repository.save(newPlayer);
// notify observers
// updated
boundObservers.forEach( observer -> observer.refreshContent() );
} catch (ValidationException e) {
e.printStackTrace();
}
});
add(button);
}
public void addObserver(ContentObserver observer) {
boundObservers.add(observer);
}
}

更改3：网格现在也是ContentObserver，因此更易于管理和理解。

public MainView(PlayerRepository repository, PlayersGrid grid, CharacterCreationForm form) {
// updated
form.addObserver(grid);
form.setWidth("30%");
// find the way to set items in the component
grid.setItems(repository.findAll());
HorizontalLayout horizontalLayout = new HorizontalLayout();
horizontalLayout.add(form);
VerticalLayout verticalLayout = new VerticalLayout();
verticalLayout.add(grid, form);
verticalLayout.setHeight("100%");
add(verticalLayout);
setClassName("main-layout");
}