禁用Vaadin绑定

Question

我有一个组件（例如TextField）将根据其他选择显示，例如单选按钮，当它被隐藏时，我不希望应用此字段上的绑定，所以

在某些地方：

Binder binder = new Binder<SomeDTO>(SomeDTO.class);
TextField conditionalComponet = TextField("A conditional component: ");
binder.bind(conditionalComponet, "propertyX");

在其他地方：

SomeDTO someDTO = new SomeDTO;
binder.writeBean(someDTO); //Here propertyX shouldn't be filled, i.e. bind should 
                       //not be applied, to propertyX of SomeDTO if the 
                       //conditionalComponet is hidden.

我不想从布局中删除组件，因为将它放在相同的位置将是一个问题。我尝试setVisible(false)，setEnabled(false)和setReadOnly(true)，但没有人阻止应用绑定。有一种简单的方法吗？

我正在使用Vaadin 8.

Answer 1

@Morfic答案不再正确。 Vaadin 8现在支持取消​​绑定字段：

TextField usernameField;

binder.forField(this.usernameField)
    .bind(User::getUsername, User::setUsername);

binder.removeBinding(this.usernameField);

Answer 2

据我所知，没有直接方法可以防止绑定时将值设置为字段。尽管如此，通过使用绑定（HasValue＆lt; FIELDVALUE＆gt;字段，ValueProvider<BEAN,FIELDVALUE> getter，Setter<BEAN,FIELDVALUE> setter）限制（?!） >方法变种。

有关示例，您可以查看以下代码。请注意，它只是显示效果的基本部分，因此它没有所有的功能，例如禁用或重置使用日期字段和复选框：

import com.vaadin.data.Binder;
import com.vaadin.data.ValidationException;
import com.vaadin.ui.*;

import java.io.Serializable;
import java.time.LocalDate;

public class DisableBindingForField extends VerticalLayout {
    private final Person person = new Person("Dark Vaper");
    private final TextField name = new TextField("Name:");
    private final CheckBox isEmployed = new CheckBox("Is employed:");
    private final DateField dateOfEmployment = new DateField("Date of employment:");
    private final Binder<Person> binder = new Binder<>(Person.class);
    private final Button button = new Button("Save");

    public DisableBindingForField() {
        // manually bind the custom field separately (https://vaadin.com/docs/-/part/framework/datamodel/datamodel-forms.html - scroll to the end)
        binder.bind(dateOfEmployment, person -> person.dateOfEmployment, (person, dateOfEmployment) ->
                // if the check-box is checked then populate the pojo with the value, otherwise reset the pojo value to null
                person.setDateOfEmployment((isEmployed.getValue()) ? dateOfEmployment : null)
        );

        // automatically bind the rest of the fields
        binder.bindInstanceFields(this);

        // initial reading of the bean
        binder.readBean(person);

        // add components to the user interface
        addComponents(name, isEmployed, dateOfEmployment, button);

        // simulate a "save button"
        button.addClickListener(event -> {
            try {
                binder.writeBean(person);
                Notification.show(person.toString());
            } catch (ValidationException e) {
                e.printStackTrace();
            }
        });
    }

    // basic pojo for binding
    public class Person implements Serializable {

        private String name;
        private Boolean isEmployed;
        private LocalDate dateOfEmployment;

        public Person(final String name) {
            this.name = name;
        }

        public String getName() {
            return name;
        }

        public void setName(final String name) {
            this.name = name;
        }

        public boolean isEmployed() {
            return isEmployed;
        }

        public void setEmployed(boolean employed) {
            isEmployed = employed;
        }

        public LocalDate getDateOfEmployment() {
            return dateOfEmployment;
        }

        public void setDateOfEmployment(LocalDate dateOfEmployment) {
            this.dateOfEmployment = dateOfEmployment;
        }

        @Override
        public String toString() {
            return "Person{" +
                    "name='" + name + '\'' +
                    ", isEmployed=" + isEmployed +
                    ", dateOfEmployment=" + dateOfEmployment +
                    '}';
        }
    }
}

结果：

P.S。：替代流利制作者风格：

binder.forField(dateOfEmployment)
      .bind(person -> person.dateOfEmployment, (person, dateOfEmployment) ->
          // if the check-box is checked then populate the pojo with the value, otherwise reset the pojo value to null
          person.setDateOfEmployment((isEmployed.getValue()) ? dateOfEmployment : null)
      );