We Keep Coding

Wicket hacked use of ListView, which alternatives?

Wicket use of models can be cumbersome. For a stateful page to properly render an object, you need to use lots of boiler-plate code, overriding classes to properly get the visibility status, etc... A simple example:
private IModel<FooBar> fooBarModel;
public MyPage() {
Label lbl1 = new Label("field1",
new PropertyModel<>(fooBarModel, "field1")) {
#Override public boolean isVisible() {
return fooBarModel.getObject().someCondition();
} }
add(lbl1);
/// Etc... same for dozen of other fields
}
I'm often using a trick using a ListView to help. Same example:
public MyPage() {
add(new ListView<FooBar>("content",
new SingleListModel<FooBar>(fooBarModel)) {
#Override protected void populateItem(...) {
FooBar fooBar = item.getModelObject();
// Code here gets simpler:
Label lbl1 = new Label("field1", fooBar.getField1());
lbl1.setVisible(fooBar.someCondition());
item.add(lbl1);
// Etc...
}
});
}
With a simple utility class SingleListModel, that transform a IModel<T> to a ListModel<T>, having 1 or 0 elements, depending whether T is null or not:
public class SingleListModel<T>
extends LoadableDetachableModel<List<T>> {
private IModel<T> tModel;
public SingleListModel(IModel<T> tModel) {
this.tModel = tModel;
}
#Override
protected List<T> load() {
List<T> ret = new ArrayList<>(1);
T t = tModel.getObject();
if (t != null)
ret.add(tModel.getObject());
return ret;
}
}
The nice side-effect of this is that the whole "content" element in the markup is hidden if fooBarModel returns null; no special treatment needed.
But all this smells like a hack to me, as I use ListView in a somehow "unnatural" fashion.
Is there a cleaner way to get the same result? A standard wicket framework?

You should use Behavior instead to avoid such duplications.
public class MyBehavior extends Behavior {
private final MyModel model;
public MyBehavior(MyModel model) {this.model = model;}
#Override public void onConfigure(Component c) {
if (model.someCondition()) {
component.setVisible(false);
}
}
}
Usage:
MyBehavior b = new MyBehavior(modelInstance);
component1.add(b);
component2.add(b);
// dozen more

Label lbl1 = new Label("field1",
new PropertyModel<>(fooBarModel, "field1")) {
#Override public boolean isVisible() {
return fooBarModel.getObject().someCondition();
} }
add(lbl1);
with little refactoring it can be converted into
add(new FLabel("id","text")
.setVisibilityFunction(()->model.getObject().isVisible()))
);
the FLabel class:
public class FLabel extends Label implements IComponentWithVisibilityFunction<FLabel> {
private SerializableBooleanSupplier visibilityFunction;
public FLabel(String id) {
super(id);
}
public FLabel(String id, Serializable label) {
super(id, label);
}
public FLabel(String id, IModel<?> model) {
super(id, model);
}
#Override
public FLabel setVisibilityFunction(SerializableBooleanSupplier visibilityFunction) {
this.visibilityFunction = visibilityFunction;
return this;
}
#Override
protected void onConfigure() {
if (visibilityFunction != null) {
setVisible(visibilityFunction.getAsBoolean());
}
}
}
public interface IComponentWithVisibilityFunction<T> {
T setVisibilityFunction(SerializableBooleanSupplier visibilityFunction);
}
Moreover you can put supplier into constructor:
add(new FLabel("id","text", ()->model.getObject().isVisible()));

Thymeleaf - how to add a custom util?

Thymeleaf has a number of useful utilities like #strings.capitalize(...) or #lists.isEmpty(...). I'm trying to add a custom one but have no idea how to register this.
Have made a custom Util class:
public class LabelUtil {
public String[] splitDoubleWord(String str) {
return str.split("[A-Z]", 1);
}
}
Now I'm going to use it like this:
<span th:each="item : ${#labels.splitDoubleWord(name)}" th:text="${item}"></span>
Of course, it won't work because I haven't registered the Util and defined #labels var.
So, the question is how and where to do it?

This answer is for thymeleaf 2.x.
If you use thymeleaf 3.x or later, please see other answers.
public class MyDialect extends AbstractDialect implements IExpressionEnhancingDialect {
public MyDialect() {
super();
}
#Override
public String getPrefix() {
// #see org.thymeleaf.dialect.IDialect#getPrefix
return "xxx";
}
#Override
public boolean isLenient() {
return false;
}
#Override
public Map<String, Object> getAdditionalExpressionObjects(IProcessingContext ctx) {
Map<String, Object> expressions = new HashMap<>();
expressions.put("labels", new LabelUtil());
return expressions;
}
}
and register your dialect.
#Configuration
public class ThymeleafConfig {
#Bean
public MyDialect myDialect() {
return new MyDialect();
}
}
thymeleaf-extras-java8time source code is good reference for creating custom thymeleaf expressions.

The API for registering a custom expression object has changed in Thymeleaf 3, for example:
public class MyDialect extends AbstractDialect implements IExpressionObjectDialect {
MyDialect() {
super("My Dialect");
}
#Override
public IExpressionObjectFactory getExpressionObjectFactory() {
return new IExpressionObjectFactory() {
#Override
public Set<String> getAllExpressionObjectNames() {
return Collections.singleton("myutil");
}
#Override
public Object buildObject(IExpressionContext context,
String expressionObjectName) {
return new MyUtil();
}
#Override
public boolean isCacheable(String expressionObjectName) {
return true;
}
};
}
}

How can I .trim() the display field of a Vaadin combobox?

In Vaadin 7.x, I have a ComboBox setup using a JPAContainer. It's setup like:
mycombo.setItemCaptionPropertyId("name");
Works great. However, the entity that is mapped to that combo uses a CHAR(50) column for the name and this cannot be changed. Everything works fine, but it's annoying to see all of those spaces when I copy/paste, for example, from the combo to some other text input.
Naturally, I .trim() the combo value when I pass it in programmatically but I would like to always trim the display automatically.
Would I do this by creating a custom converter?
Thanks

Due to a lack of time I can't find anything better than the following:
public class MyVaadinUI extends UI {
#WebServlet(value = "/*", asyncSupported = true)
#VaadinServletConfiguration(productionMode = false, ui = MyVaadinUI.class, widgetset = "com.gabrielruiu.vaadin.AppWidgetSet")
public static class Servlet extends VaadinServlet {
}
#Override
protected void init(VaadinRequest request) {
final VerticalLayout layout = new VerticalLayout();
layout.setMargin(true);
setContent(layout);
ComboBox comboBox = new ComboBox("my combobox", Arrays.asList(" Killer croc ", " Joker", "Penguin "));
comboBox.setConverter(new Converter<Object, String>() {
#Override
public String convertToModel(Object value, Class<? extends String> targetType, Locale locale) throws ConversionException {
if (value != null) {
return value.toString();
}
return null;
}
#Override
public Object convertToPresentation(String value, Class<?> targetType, Locale locale) throws ConversionException {
if (value != null) {
return value.trim();
}
return null;
}
#Override
public Class<String> getModelType() {
return String.class;
}
#Override
public Class<Object> getPresentationType() {
return Object.class;
}
});
layout.addComponent(comboBox);
}
}
The problem is that, while testing it, the value in the combobox disappears after I select it. If you can find a solution then that's great but this is what I could scrounge up for the moment.

How to select one of GWT CellTree nodes after first data fetch?

I'm trying to select first root node of the CellTree after asynchronous data fetching from server. Here is my code:
public class MyTreeModel implements TreeViewModel{
private MyServiceAsync myService = GWT.create(MyService.class);
public <T> NodeInfo<?> getNodeInfo(T value) {
Cell<MyTO> cell = new AbstractCell<MyTO>() {
#Override
public void render(Context context, MyTO value, SafeHtmlBuilder sb) {
//rendering node...
}
};
return new DefaultNodeInfo<MyTO>(value instanceof MyTO ?
createBranchDataProvider((MyTO)value) : //fetching child nodes
cerateRootDataProvider(), cell); //fetching root nodes
}
#Override
public boolean isLeaf(Object value) {
if (value instanceof MyTO) {
MyTO to = (MyTO)value;
return to.isLeafNode();
}
return false;
}
private AbstractDataProvider<MyTO> cerateRootDataProvider() {
AsyncDataProvider<MyTO> dataProvider = new AsyncDataProvider<MyTO>() {
#Override
protected void onRangeChanged(HasData<MyTO> display) {
AsyncCallback<List<MyTO>> callback = new AsyncCallback<List<MyTO>>() {
#Override
public void onSuccess(List<MyTO> result) {
updateRowCount(result.size(), true);
updateRowData(0, result);
}
#Override
public void onFailure(Throwable caught) {
Window.alert(caught.toString());
}
};
myService.getRootNodes(callback);
}
};
return dataProvider;
}
private AbstractDataProvider<MyTO> createBranchDataProvider(final MyTO value) {
AsyncDataProvider<MyTO> dataProvider = new AsyncDataProvider<MyTO>() {
#Override
protected void onRangeChanged(HasData<MyTO> display) {
AsyncCallback<List<MyTO>> callback = new AsyncCallback<List<MyTO>>() {
#Override
public void onSuccess(List<MyTO> result) {
updateRowCount(result.size(), true);
updateRowData(0, result);
}
#Override
public void onFailure(Throwable caught) {
Window.alert(caught.toString());
}
};
myService.getChildNodes(value.getId(), callback);
}
};
return dataProvider;
}
For data which stored on client side solution looks pretty simple: we could just call something like
tree.getRootTreeNode().setChildOpen(0, true, true);
but if we want to fetch data asynchronously we will catch IndexOutOfBoundsException in case we try the same immediately after creation tree, because data is not obtained yet. How can I know when onSuccess() event will be fired in cerateRootDataProvider()? Or I could use another solution? Please suggest something.

I see two options for calling
tree.getRootTreeNode().setChildOpen(0, true, true);
in a right moment:
Direct dependency on presenter: add a constructor for your MyTreeModel object. Send corresponding presenter as a parameter. Add and call something like presenter.onDataLoadingComplete() at the end of onSuccess method.
Custom event: create your custom event. Fire it at the end of onSuccess method. Subscribe to it in some place where you can call access `tree``object. Call necessary code.

Binding in JavaFX 2.0

Maybe I missunderstood JavaFX binding or there is a bug in SimpleStringProperty.
When I run this testcode my changed model value didn't get the new value. Test testBindingToModel fails. I thought my model should then be updated with the value of the TextField tf. But only the binding value of prop1Binding gets the value "test".
public class BindingTest {
private TextField tf;
private Model model;
private ModelBinding mb;
#Before
public void prepare() {
tf = new TextField();
model = new Model();
mb = new ModelBinding(model);
Bindings.bindBidirectional(tf.textProperty(), mb.prop1Binding);
}
#Test
public void testBindingToMB() {
tf.setText("test");
assertEquals(tf.getText(), mb.prop1Binding.get());
}
#Test
public void testBindingToModel() {
tf.setText("test");
assertEquals(tf.getText(), mb.prop1Binding.get());
assertEquals(tf.getText(), model.getProp1());
}
private static class ModelBinding {
private final StringProperty prop1Binding;
public ModelBinding(Model model) {
prop1Binding = new SimpleStringProperty(model, "prop1");
}
}
private static class Model {
private String prop1;
public String getProp1() {
return prop1;
}
public void setProp1(String prop1) {
this.prop1 = prop1;
}
}
}
Thanks for your help.
Best regards
Sebastian
EDIT:
With this class I can set the value of the model directly. I will test this class in the next days and comment on this post with my result.
public class MySimpleStringProperty extends SimpleStringProperty {
public MySimpleStringProperty(Object obj, String name) {
super(obj, name);
}
public MySimpleStringProperty(Object obj, String name, String initVal) {
super(obj, name, initVal);
}
#Override
public void set(String arg0) {
super.set(arg0);
if (this.getBean() != null) {
try {
Field f = this.getBean().getClass().getDeclaredField(this.getName());
f.setAccessible(true);
f.set(this.getBean(), arg0);
} catch (NoSuchFieldException e) {
// logging here
} catch (SecurityException e) {
// logging here
} catch (IllegalArgumentException e) {
// logging here
} catch (IllegalAccessException e) {
// logging here
}
}
}
}

This constructor doesn't attach SimpleStringProperty to a bean object unfortunately. It just says to SimpleStringProperty which bean property belongs to.
E.g., if you want to have a property in your class you should do it next way:
public static class Model {
private StringProperty prop1 =
new SimpleStringProperty(this, "prop1", "default_value");
public String getProp1() {
return prop1.get();
}
public void setProp1(String value) {
prop1.set(value);
}
public StringProperty prop1Property() {
return prop1;
}
}
Note, that there is no way to bind to your original Model class as it provides no events about setting new prop1 value. If you want to have observable model, you should use fx properties from the beginning.

Just figured out that there is provided the class JavaBeanStringProperty, which just fullfill my request.
Using this code I can directly bind the value of my bean to a StringProperty (included setting and getting of my value to / from my Bean).
binding = JavaBeanStringPropertyBuilder.create().beanClass(Model.class).bean(model).name("prop1").build();
The only problem I found is that when you change the value of the model after setting the binding, there is no update e.g. in the TextField.