Vaadin绑定对象

Question

我正在尝试将文本字段绑定到对象。我做了一些研究，找到了这个答案。

public class Person {

 String name;
 String surname;
 Address address;

 // assume getters and setters
}

public class Address {

 String street;

 // assume getter and setters
}

然后，您可以像这样绑定街道地址：

Binder<Person> binder = new Binder<>();

TextField streetAddressField = new TextField();

// bind using lambda expressions

binder.bind(streetAddressField,
person -> person.getAddress().getStreet(),
(person, street) -> person.getAddress().setStreet(street));

我将Street实例化为什么值（在最后一行代码中）？

以上是我找到的例子。我的代码如下——我有一个联系类:

@Entity
public class Contact {

    @Id
    @GeneratedValue
    private Long id;

    private String firstName;

    private String lastName;

    private String phoneNumber;


    @ManyToOne (cascade = {CascadeType.ALL})
    @JoinColumn(name="phoneType_typeId")
    private PhoneType phoneType;

    public Contact(){

    }

    public Contact(String firstName, String lastName, String phoneNumber, PhoneType type) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.phoneNumber = phoneNumber;
        this.phoneType = type;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getPhoneNumber() {
        return phoneNumber;
    }

    public void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }

    public PhoneType getPhoneType() {
        return phoneType;
    }

    public void setPhoneType(PhoneType phoneType) {
        this.phoneType = phoneType;
    }

    @Override
    public String toString() {
        return String.format("Contact[firstName='%s', lastName='%s', phoneNumber='%s', phoneType = '%s']",
                firstName, lastName, phoneNumber, phoneType);
    }
}

然后我有一个phoneType类:

@Entity
@Table(name="phoneType")
public class PhoneType {


    @Id
    @GeneratedValue
    @Column(name = "typeId")
    private Long id;

    private String type;

    public PhoneType(String type){
        this.type = type;
    }

    public PhoneType(){}

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    @Override
    public String toString() {
        return type;
    }
}

然后在联系人编辑器中，我试图将phoneType绑定到文本字段：

@SpringComponent
@UIScope
public class ContactEditor extends VerticalLayout {

    private final ContactRepository repository;

    private Contact contact;

    TextField firstName = new TextField("First name");
    TextField lastName = new TextField("Last name");
    TextField phoneNumber = new TextField("Phone number");
    TextField phoneType = new TextField( "Phone type");

    Button save = new Button("Save", VaadinIcons.CHECK);
    Button cancel = new Button("Cancel");
    Button delete = new Button("Delete", VaadinIcons.TRASH);
    CssLayout actions = new CssLayout(save, cancel, delete);

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


    @Autowired
    public ContactEditor(ContactRepository repository, Contact contact) {
        this.repository = repository;
        this.contact = contact;
        String type = contact.getPhoneType().getType();

        addComponents(firstName, lastName, phoneNumber, phoneType, actions);

        // bind using naming convention
        **binder.bind(phoneType, contact.getPhoneType().getType(), contact.getPhoneType().setType(type));**
        binder.bindInstanceFields(this);

        // Configure and style components
        setSpacing(true);
        actions.setStyleName(ValoTheme.LAYOUT_COMPONENT_GROUP);
        save.setStyleName(ValoTheme.BUTTON_PRIMARY);
        save.setClickShortcut(ShortcutAction.KeyCode.ENTER);

        // wire action buttons to save, delete and reset
        save.addClickListener(e -> repository.save(contact));
        delete.addClickListener(e -> repository.delete(contact));
        cancel.addClickListener(e -> editContact(contact));
        setVisible(false);
    }

    public interface ChangeHandler {

        void onChange();
    }

    public final void editContact(Contact c) {
        if (c == null) {
            setVisible(false);
            return;
        }
        final boolean persisted = c.getId() != null;
        if (persisted) {
            // Find fresh entity for editing
            contact = repository.findById(c.getId()).get();
        }
        else {
            contact = c;
        }
        cancel.setVisible(persisted);

        // Bind customer properties to similarly named fields
        // Could also use annotation or "manual binding" or programmatically
        // moving values from fields to entities before saving
        binder.setBean(contact);

        setVisible(true);

        // A hack to ensure the whole form is visible
        save.focus();
        // Select all text in firstName field automatically
        firstName.selectAll();
    }

    public void setChangeHandler(ChangeHandler h) {
        // ChangeHandler is notified when either save or delete
        // is clicked
        save.addClickListener(e -> h.onChange());
        delete.addClickListener(e -> h.onChange());
    }


}

在联系人编辑器中，包含在**中的行（即 binder.bind（电话类型，联系人.getPhoneType（）.getType（），联系人.getPhoneType（）.setType（类型）））中包含的行给我一个错误 - “不存在类型变量 FIELDVALUE 的实例，因此字符串符合值提供者。

Answer 1

我不知道这是不是你的要求，但我认为你缺少的是你没有把活页夹绑在任何豆子上。

您已经创建了绑定器，并告诉了textfield绑定了哪个属性，但是现在您需要告诉绑定器哪个是他的bean。

像这样：

Person yourPerson = new Person(); //or get person from database somehow
yourPerson.setAddress(new Address());
yourPerson.getAddress().setStreet("Road cool code, 404");
binder.setBean(yourPerson);

这应该会奏效……如果不行，请更好地解释你需要什么。；）

Answer 2

这条线

binder.bind(phoneType, contact.getPhoneType().getType(), contact.getPhoneType().setType(type));

无法编译，因为方法参数与任何bind方法都不匹配，并且第三个参数中存在非法的Java表达式。根据你的问题，你只是忘记了使用lambdas。尝试：

binder.bind(phoneType, c -> c.getPhoneType().getType(), (c, t) -> c.getPhoneType().setType(t));

看看方法签名：

public <FIELDVALUE> Binder.Binding<BEAN,FIELDVALUE> bind(HasValue<FIELDVALUE> field,
                                                     ValueProvider<BEAN,FIELDVALUE> getter,
                                                     Setter<BEAN,FIELDVALUE> setter)

它期望ValueProvider和Setter作为第二和第三个参数。这些接口只有一个方法要实现，因此您可以使用lambda将它们传递给bind。