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，当它隐藏时我不希望应用此字段上的绑定，所以

在某个地方：

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该组件，因为将它放在同一位置会出现问题。我尝试 setVisible(false)、setEnabled(false) 和 setReadOnly(true)，但 none 阻止应用绑定。有简单的方法吗？

我正在使用 Vaadin 8。

Answer 1

据我所知，没有直接 方法可以防止值在绑定后被活页夹设置为字段。尽管如此，您可以通过使用 bind(HasValue field, ValueProvider<BEAN,FIELDVALUE> getter, Setter<BEAN,FIELDVALUE> setter)[=31= 轻松解决此 limitation(?!) ] 方法变体。

您可以查看下面的代码作为示例。请注意，它只有显示效果的基本部分，因此它没有所有花哨的功能，例如使用复选框禁用或重置就业日期字段：

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fluent-builder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)
      );

Answer 2

@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);