Question

我有一个类似

的对象

public class Table {
    private String id;
    private String name;
    private List<Field> fieldsList;
}

public class Field {
    private List<Column> columnList;
}

public class Column{
    String id;
}

所以，这里我的工作流程是一个由多个Field组成的Table，一个Field将有多个Column。因此，在webUI上，我需要显示一个名称和字段下拉列表作为行。当用户选择一个字段时，我需要动态获取所选字段并渲染属于所选字段的列。这里，如何从Web UI获取所选字段。我尝试使用AjaxFormComponentUpdatingBehavior（“onchange”）。但我得到了那个下拉列表的所有领域。

我的DropDown选择如下：

IChoiceRenderer choiceRenderer = new ChoiceRenderer("Name", "id");
DropDownChoice dropDownChoice = new DropDownChoice("ddc");
dropDownChoice.setChoiceRenderer(choiceRenderer);
dropDownChoice.setChoices(table.getFieldsList());
dropDownChoice.setModel(new CompoundPropertyModel(new Field()));

dropDownChoice.add(new AjaxFormComponentUpdatingBehavior("onchange") {

@Override
protected void onUpdate(AjaxRequestTarget target) {
   //Following is returning all the List of Fields.
   Object defaultModelObject = getModelObject();
 }
});

如何处理此类情况。请帮忙......

Answer 1

请参阅下面的完整示例。主要部分是ViewModel（VM）和ViewModelLoader（VML）。 VM是您要在UI中显示的内容。 VML使用来自数据库的数据填充VM。使用PropertyModel我绑定下拉项和选定的值。要更新doropdown，我正在更新VM并将组件添加到AjaxRequestTarget。

  public class PlayingWithDropDownPage extends WebPage {

        public PlayingWithDropDownPage() {
            final ViewModelLoader viewModelLoader = new ViewModelLoader();
            final ViewModel viewModel = viewModelLoader.load();

            IChoiceRenderer choiceRenderer = new ChoiceRenderer("name", "id");
            final DropDownChoice dropDownChoice = new DropDownChoice("dropDown");
            dropDownChoice.setChoiceRenderer(choiceRenderer);
            dropDownChoice.setChoices(viewModel.getItemsModel());
            dropDownChoice.setModel(viewModel.getSelectedModel());

            dropDownChoice.add(new AjaxFormComponentUpdatingBehavior("onchange") {
                @Override
                protected void onUpdate(AjaxRequestTarget target) {
                    viewModelLoader.load(viewModel);

                    target.add(dropDownChoice);
                }
            });
            add(dropDownChoice);
        }

        public static class ViewModel implements Serializable {
            private WhatToShow whatToShow;
            private List<Item> items = new ArrayList<>();
            private Item selected;

            public IModel<List<Item>> getItemsModel() {
                return new PropertyModel<>(this, "items");
            }

            public IModel<Item> getSelectedModel() {
                return new PropertyModel<>(this, "selected");
            }
        }

        public static class ViewModelLoader extends LoadableDetachableModel<ViewModel> {

            @Override
            protected ViewModel load() {
                return load(new ViewModel());
            }

            protected ViewModel load(ViewModel vm) {
                vm.items.clear();

                if (vm.whatToShow == WhatToShow.City) {
                    vm.whatToShow = WhatToShow.Person;
                    vm.items.add(new Person("1", "John", "Smith"));
                    vm.items.add(new Person("2", "Robert", "Evans"));
                    vm.items.add(new Person("3", "Jeff", "Jones"));
                } else {
                    vm.whatToShow = WhatToShow.City;
                    vm.items.add(new City("1", "London"));
                    vm.items.add(new City("2", "Moscow"));
                    vm.items.add(new City("3", "Kiev"));
                }

                return vm;
            }
        }

        public static interface Item {
            public String getId();

            public String getName();
        }

        private enum WhatToShow {
            Person,
            City
        }

        public static class City implements Item {

            public String id;
            public String name;

            public City(String id, String name) {
                this.id = id;
                this.name = name;
            }

            @Override
            public String getId() {
                return id;
            }

            @Override
            public String getName() {
                return name;
            }
        }

        public static class Person implements Item {
            public String id;
            public String fname;
            public String lname;

            public Person(String id, String fname, String lname) {
                this.id = id;
                this.fname = fname;
                this.lname = lname;
            }

            @Override
            public String getId() {
                return id;
            }

            @Override
            public String getName() {
                return String.format("%s %s", fname, lname);
            }
        }
    }

Apache Wicket：从UI上的表中获取选定的下拉值

1 个答案: