I have a larger application that I'm working with but the GWT History documentation has a simple example that demonstrates the problem. The example is copied for convenience:
public class HistoryTest implements EntryPoint, ValueChangeHandler
{
private Label lbl = new Label();
public void onModuleLoad()
{
Hyperlink link0 = new Hyperlink("link to foo", "foo");
Hyperlink link1 = new Hyperlink("link to bar", "bar");
Hyperlink link2 = new Hyperlink("link to baz", "baz");
String initToken = History.getToken();
if (initToken.length() == 0)
{
History.newItem("baz");
}
// Add widgets to the root panel.
VerticalPanel panel = new VerticalPanel();
panel.add(lbl);
panel.add(link0);
panel.add(link1);
panel.add(link2);
RootPanel.get().add(panel);
History.addValueChangeHandler(this); // Add history listener
History.fireCurrentHistoryState();
}
#Override
public void onValueChange(ValueChangeEvent event)
{
lbl.setText("The current history token is: " + event.getValue());
}
}
The problem is that if you refresh the application, the history stack gets blown away. How do you preserve the history so that if the user refreshes the page, the back button is still useful?
I have just tested it with Firefox and Chrome for my application and page refresh does not clear the history. Which browser do you use? Do you have the
<iframe src="javascript:''" id='__gwt_historyFrame' style='position:absolute;width:0;height:0;border:0'></iframe>
in your HTML?
GWT has catered for this problem by providing the History object. By making a call to it's static method History.newItem("your token"), you will be able to pass a token into your query string.
However you need to be aware that any time there is a history change in a gwt application, the onValueChange(ValueChangeEvent event){} event is fired, and in the method you can call the appropriate pages. Below is a list of steps which i use to solve this problem.
Add a click listener to the object that needs too call a new page. In handling the event add a token to the history.(History.newItem("new_token").
Implement the ValueChangeHandler in the class that implements your EntryPoint.
Add onValueChangeHandler(this) listener to the class that implements the EntryPoint. Ensure that the line is add in the onModuleLoad() method (it is important it is added in this method) of the class that implements the EntryPoint(pretty obvious ha!)
Finally implement onValueChange(ValueChangeEvent event){ //call a new page } method.
That's it
Related
My problem is with how to stop firing unrelated event of event bus. as I got this solution for Dialog box.
but it does not work in case of where one instance already initialize and try to create new instance of same class.
Just example: A below scroll panel has handler initialized. it used for document preview.
class TestScroll extends ScrollPanel
{
public TestScroll(){
}
implemented onload()
{
// eventBus.addHandler code here.
//here some preview related code
}
unload() method
{
//eventBus remove handler code
}
}
This preview has some data which contains some links that open different preview but with same class and different data structure,
Now The problem is like onUnload ( which contains code of remove handler) event does not load , because other panel opened. that does not mean previous panel unload.
So in that case, twice event handler registered. when one event fired then other event also fired.
Due to that, Preview 1 data shows properly, but after that Preview2 opened and when I close it, I find Preview1=Preview2.
so how can I handle such situation?
As per no of instance created each event fired. but I have to check some unique document id with if condition in event itself.
is there any other ways to stop unrelated event firing?
Edit:
public class Gwteventbus implements EntryPoint {
int i=0;
#Override
public void onModuleLoad() {
TestApp panel=new TestApp();
Button button=new Button("Test Event");
button.addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
TestApp panel=new TestApp();
int j=i;
new AppUtils().EVENT_BUS.fireEventFromSource(new AuthenticationEvent(),""+(j));
i++;
}
});
panel.add(button);
RootPanel.get().add(panel);
}
}
public class AppUtils {
public static EventBus EVENT_BUS = GWT.create(SimpleEventBus.class);
}
public class TestApp extends VerticalPanel{
String testString="";
public TestApp( ) {
AppUtils.EVENT_BUS.addHandler(AuthenticationEvent.TYPE, new AuthenticationEventHandler() {
#Override
public void onAuthenticationChanged(AuthenticationEvent authenticationEvent) {
System.out.println("helloworld"+authenticationEvent.getSource());
}
});
}
}
These are wild guesses as it's difficult to really answer it without code and a clear description.
I'm guessing you have one eventbus for all the panels. So when you register a handler it is registered with that one eventbus. In case you fire an event from one of the panels to the eventbus all panels will receive the event.
To fix this you can either create a new eventbus per panel or check who fired the event with event.getSource().
If this doesn't make sense you probably are reusing a variable or use a static variable which actually should be a new instance or none static variable.
You can use the GwtEventService-Library to fire specific events over a unique domain and every receiver that is registered at this domain receives that events then. You can handle as many different events/domains as you want.
In order to remove a handler attached to the EventBus, you must first store a reference to the HandlerRegistration returned by the addHandler method:
HandlerRegistration hr = eventBus.addHandler(new ClickHandler(){...});
Then you can remove the handler with the removeHandler method:
hr.removeHandler();
A final note worth mentioning is that when using singleton views, like is typical with MVP and GWT Activities and Places, it is best practice to make use of a ResettableEventBus. The eventBus passed to an activity's start() is just such a bus. When the ActivityManager stops the activity, it automatically removes all handlers attached to the ResettableEventBus.
I would strongly recommend reading the GWT Project's documentation on:
Activities and Places
Large scale application development and MVP
I have couple of drop downdowns and a download link button. Based on the user selection, i get the file to be downloaded. if the user did not make a selection I show an error on the feedback panel. if the user then makes a selection and clicks on download link it works fine, but the previous feedback message is still visible. How do I clear it.
onclick of the download link, i tried the following, but no use
FeedbackMessages me = Session.get().getFeedbackMessages();
me.clear();
Probably it is
Session.get().cleanupFeedbackMessages()
even it has been changed in Wicket 6.x
I've found this post and I think it is time to share the way for Wicket 6.x and for Wicket 7.x, because Session.get().cleanupFeedbackMessages() was deprecated already.
To do it for Wicket 6.x you have to implement additional filter for the feedback panel. Where to do it, it is your decision to decide.
Create a new FeedbackPanel implementation by extending from the existing FeedBackPanel class
private class MessagesFeedbackPanel extends FeedbackPanel{
private MessageFilter filter = new MessageFilter();
public MessagesFeedbackPanel(String id){
super(id);
setFilter(filter);
}
#Override
protected void onBeforeRender(){
super.onBeforeRender();
// clear old messages
filter.clearMessages();
}
}
Provide a new Filter implementation, by implementing the existing IFeedbackMessageFilter interface
public class MessageFilter implements IFeedbackMessageFilter{
List<FeedbackMessage> messages = new ArrayList<FeedbackMessage>();
public void clearMessages(){
messages.clear();
}
#Override
public boolean accept(FeedbackMessage currentMessage){
for(FeedbackMessage message: messages){
if(message.getMessage().toString().equals(currentMessage.getMessage().toString()))
return false;
}
messages.add(currentMessage);
return true;
}
}
Following code works for me in Wicket 6:
public class MyComponent extends Panel {
...
FeedbackMessages feedback = getFeedbackMessages();
feedback.clear();
I'm trying to do the following:
I want to add a specific handler for some links, denoted by a class.
$("a.link_list").live("click", new ListLinkHandler());
I need .live() instead of .bind() because new such links will be generated. (I know jQuery's .live() is deprecated in favor of .on(), but gwt-query doesn't have a .on() yet.)
I defined the handler like this (just as the gwtquery example does):
public class ListLinkHandler extends Function {
#Override
public boolean f(Event e) { [...] }
}
However, the handler method is never called when I click the links.
I can see the event listener in Chrome Dev Tools: http://screencloud.net/v/bV5V. I think it's on the body because it's a .live().
I tried using .bind() and it worked fine. The body event listener changed in a a.link_list and the handler does what it's supposed to do, but (as documented, I didn't test) not for newly created links.
I filed a bug for the .live() method, but maybe I'm doing something wrong.
Also, I have no idea how to do it without gwtquery, GWT doesn't seem to have a method for selecting elements by class, neither to continually add the listener to new elements.
It seems you are doing something wrong, but I need more code to be sure. Could you send the complete onModuleLoad code which demonstrates this wrong behavior?
I have written a quick example using live, and it works either when adding new gwt widgets or dom elements with gquery, in both Chrome and FF
public void onModuleLoad() {
$("a.link_list").live("click", new ListLinkHandler());
// Add a new link via gquery
$("<a class='link_list' href=javascript:alert('href') onClick=alert('onClick')>Click </a>").appendTo(document);
// Add a new link via gwt widgets
Anchor a = new Anchor("click");
a.setStyleName("link_list");
a.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
Window.alert("clickHandler");
}
});
RootPanel.get().add(a);
}
public class ListLinkHandler extends Function {
#Override
public boolean f(Event e) {
Window.alert("live");
return true;
}
}
I'm using GWT 2.4 with JUnit 4.8.1. When writing my class that extends GWTTestCase, I want to simulate clicking on a button on the page. Currently, in my onModuleLoad method, this button is only a local field ...
public void onModuleLoad() {
final Button submitButton = Button.wrap(Document.get().getElementById(SUBMIT_BUTTON_ID));
...
// Add a handler to send the name to the server
GetHtmlHandler handler = new GetHtmlHandler();
submitButton.addClickHandler(handler);
How do I simulate clicking on this button from the GWTTestCase? Do I have to expose this button as a public member accessor is there a more elegant way to access it? Here is what I have in my test case so far ...
public class GetHtmlTest extends GWTTestCase {
// Entry point class of the GWT application being tested.
private Productplus_gwt productPlusModule;
#Override
public String getModuleName() {
return "com.myco.clearing.productplus.Productplus_gwt";
}
#Before
public void prepareTests() {
productPlusModule = new Productplus_gwt();
productPlusModule.onModuleLoad();
} // setUp
#Test
public void testSuccessEvent() {
// TODO: Simulate clicking on button
} // testSuccessEvent
}
Thanks, - Dave
It can be as easy as buttonElement.click() (or ButtonElement.as(buttonWidget.getElement()).click(), or ButtonElement.as(Document.get().getElementById(SUBMIT_BUTTON_ID)).click())
But remember that a GWTTestCase doesn't run in your own HTML host page, but an empty one, so you'll first have to insert your button within the page before simulating your module's load.
gwt-test-utils seems to be the perfect framework to answer your need. Instead of inheriting from GWTTestCase, extend the gwt-test-utils GwtTest class and implement your click test with the Browser class, like shown in the getting starting guide :
#Test
public void checkClickOnSendMoreThan4chars() {
// Arrange
Browser.fillText(app.nameField, "World");
// Act
Browser.click(app.sendButton);
// Assert
assertTrue(app.dialogBox.isShowing());
assertEquals("", app.errorLabel.getText());
assertEquals("Hello, World!", app.serverResponseLabel.getHTML());
assertEquals("Remote Procedure Call", app.dialogBox.getText());
}
If you want to keep your button private, you'd be able to retrieve it by introspection. But my advice is to make you view's widgets package protected and to write your unit test in the same package so it could access them. It's more convinent and refactoring-friendly.
gwt-test-utils provide introspection convinence. For example, to retrieve the "dialogBox" field which could have been private, you could have do this :
DialogBox dialogBox = GwtReflectionUtils.getPrivateFieldValue(app, "dialogBox");
But note that using GwtReflectionUtils is not mandatory. gwt-test-utils allows you to use ANY java classes in GWT client side tests, without restriction :)
You can do it like this:
YourComposite view = new YourComposite();
RootPanel.get().add(view);
view.getSubmitButton.getElement().<ButtonElement>cast().click();
Hello I am working on a GWT sample history management application.
Here is my onModuleLoad Code.
public void onModuleLoad() {
ContentPanel panel = ContentPanel.getInstance();
if(History.getToken()!=null && History.getToken().length()==0)
{
History.newItem("first_page");
}
History.addValueChangeHandler(new HistoryHandler());
RootPanel.get().add(panel);
History.fireCurrentHistoryState();
}
In this I fired History.fireCurrentHistoryState(); to fire current state of history.
Now In my firstPanel class ther is button named Second Panel on which history token second_page is fired.
public FirstPanel() {
VerticalPanel panel = new VerticalPanel();
Button button2 = new Button("Second Panel");
button2.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
History.newItem("second_page");
}
});
panel.add(button2);
initWidget(panel);
}
But here no need to fire History.fireCurrentHistoryState() ; again.
simply histtory.newItem works fine.
Now I want to know that what the need of History.fireCurrentHistoryState() at module load time only?
Also why it is not required second time in the application.?
History.fireCurrentHistoryState() invokes your history handlers without actually inserting new history item in browser history stack, while History.newItem(token) does insert new history token into history stack.
Note: if your current token is the same as new token (i.e. same page is reloaded), then browsers do not insert this into history stack. In this case (current token == new token) History.fireCurrentHistoryState() has the same effect as History.newItem(currentToken).