Im getting crazy about this issue. I implemented a ListView which you can add/remove TextField dinamically, but only the last TextField is removed.
An example:
// Object type which is used in the list
public class ExampleObject implements Serializable{
private String keyword;
public String getKeyword() {
return this.keyword;
}
public void setKeyword(String s) {
keyword = s;
}
}
//ListView
List<ExampleObject> keywordList = new ArrayList<ExampleObject>();
keywordList.add(new ExampleObject());
ListView keywordView = new ListView("keywordView", keywordList) {
#Override
protected void populateItem(final ListItem item) {
ExampleObject model = (ExampleObject) item.getModelObject();
item.add(new TextField("subKeyword", new PropertyModel(model, "keyword")));
// keyword remove link
AjaxSubmitLink removeKeyword = new AjaxSubmitLink("removeKeyword", myForm)
{
#Override
protected void onSubmit(AjaxRequestTarget target, Form<?> form) {
ExampleObject selected = (ExampleObject) item.getModelObject();
// I also tried deleting by index. println shows the
// selected object is the element I want to remove, so why always
// remove last object of the list?
keywordList.remove(selected);
if (target != null) {
target.addComponent(myForm);
}
}
};
item.add(removeKeyword);
// keyword add link
AjaxSubmitLink addKeyword = new AjaxSubmitLink("addKeyword", metadataForm)
{
#Override
protected void onSubmit(AjaxRequestTarget target, Form<?> form) {
keywordList.add(new ExampleObject());
if (target != null) {
target.addComponent(myForm);
}
}
};
item.add(addKeyword);
}
keywordView.setReuseItems(true);
metadataForm.add(keywordView);
Any help would be very appreciate, because I thing this issue is really a very stupid mistake but I cant get it!
Thanks
It might be as simple as getting rid of the line
keywordView.setReuseItems(true);
The reuseItems flag is an efficiency so that the page does not rebuild the ListView items unnecessarily, but it can lead to confusion such as what you're seeing.
ListView really wasn't made for use with forms though, and you'll probably be better off with another tactic entirely.
This blog entry on building a list editor form component might be useful. It will need some changes if you're not on Wicket 1.4, but similar stuff is definitely possible in Wicket 1.3, and the comments have some hints.
Read the javadoc of ListView#setReuseItems():
"But if you modify the listView model object, than you must manually call listView.removeAll() in order to rebuild the ListItems."
You can not use a ListView this way. Either use the members of ListView provided:
removeLink(java.lang.String id, ListItem<T> item)
and
newItem(int index)
but, I never used those. If I have to display a List and be able to add remove Items dynamically, I prefer the RefreshingView.
If you do use FormComponents inside a RefreshingView, make sure you set a Reusestartegy (setItemReuseStrategy())
Bert
Related
I'm new to Xamarin and C#, so apologies in advance for any mistakes I make.
In my app, I have a list of plants. When a plant is selected, I have a detail view of info about the plant. In the detail view, I have a button that adds or removes the plant from a shopping list.
To implement this, I have a class named MyPlant, with a field called InCart, and a method ToggleInCart that the button calls.
(note that I didn't paste in some code to simplify this question as much as possible)
public class MyPlant : INotifyPropertyChanged
{
string name;
bool inCart;
...
public bool InCart
{
set
{
if (inCart != value)
{
inCart = value;
OnPropertyChanged("InCart");
}
}
get { return inCart; }
}
public ICommand ToggleCartStatus
{
get
{
if (_toggleCartStatus == null)
{
_toggleCartStatus = new Command(() => InCart = !InCart);
}
return _toggleCartStatus;
}
I have another class called PlantList, which has a method PlantsInCart that uses LINQ to return an ObservableCollection of MyPlant where InCart is true.
public class PlantList : INotifyPropertyChanged
{
public ObservableCollection PlantsInCart
{
private set { }
get
{
ObservableCollection list = new ObservableCollection(myPlants.Where(i => i.InCart));
return list;
}
}
In my XAML, I have a ListView bound to PlantsInCart.
Everything works as I want EXCEPT when I remove the selected plant, the list doesn't update to show the plant is missing even though the data underneath it is correctly updated. If I refresh the list by going to a different page and coming back, then the list shows the right plants.
I suspect this doesn't work because the change in the InCart field isn't bubbling up high enough to that the ListView hears that it is supposed to update.
Can anybody advise me on the proper way to implement this kind of feature? In other words, how should you implement a scenario where you have a list that should update when a property of an item in the list changes?
I have a form with many input-fields and need to handle a change to any of those input-fields; so I add a AjaxEventBehavior to the form, like:
Form<MyX> myForm = new Form<>("X", getModel());
myForm.add(new AjaxEventBehavior("onchange") {
#Override
protected void onEvent(AjaxRequestTarget target) {
handleFormChange(...);
}
});
The method handleFormChange gets called everytime I change some content in the input-fields of the form. But the model is not getting updated with the new value of the changed input-field of the form.
How can I get thoose model-updates? I tried AjaxFormComponentUpdatingBehavior. It updates the model, but I cannot use it for forms, just for FormComponents.
Does anybody has an ideas how to handle that? TIA!
With AjaxFormSubmitBehavior you can submit the whole form on each change.
First for on change use the dedicated OnChangeAjaxBehavior.
Then you can use the Iterator of the form to get all children and add then add the OnChangeAjaxBehavior to all FormComponents which will call your handleFormChange() on every change like this:
for (Iterator it = form.iterator(); it.hasNext();) {
Object o = it.next();
if (o instanceof FormComponent) {
((FormComponent) o).add(new OnChangeAjaxBehavior() {
#Override
protected void onUpdate(AjaxRequestTarget target) {
handleFormChange(...);
}
});
}
}
I am using Prism 2, trying to add four navigation buttons (First Record, Last Record, Previous Record, Next Record) in shell to be used by modules. I also want these buttons to be disable if active View/ViewModel does not provide these functions.
I tried using events but didn't know how to achieve my second goal regarding disabling buttons. It seems I need to check current active View/ViewModel to see if they subscribed the click event during View switch. But I think publisher should be unaware of subscriber...
Somehow I tried my own way. I create an IDocNavigation interface which has four method corresponding to my four buttons. At runtime I check modules' ViewModel if they implemented that interface or not, and change the ICommand on fly. Below is my code. I include one LastRecordCommand only:
public ShellViewModel(Views.Shell shell)
{
this.Shell = shell;
shell.DataContext = this;
shell.MainDocking.ActivePaneChanged += (s, e) =>
{
if (e.NewPane.Content is UserControl &&
((UserControl)e.NewPane.Content).DataContext is IDocumentNavigate)
{
IDocumentNavigate vm = ((UserControl)e.NewPane.Content).DataContext as IDocumentNavigate;
LastRecordCommand = new RelayCommand(x => vm.GotoLastRecord(), x => true);
}
else
{
LastRecordCommand = new RelayCommand(x => { }, x => false);
}
};
//...
I feel these are quite ugly. Creating an empty RelayCommand is also stupid. How can I improve ? or how can I achieve disabling command if event is more suitable in my case ?
You can make use of CompositeCommand in prism.
Define a globally available CompositeCommand
public static readonly CompositeCommand FirstRecord= new CompositeCommand(true);
Then in your your module view models
class Module1
{
public DelegateCommand Module1Firstrecord{ get; set; }
Module1()
{
Module1Firstrecord = new DelegateCommand(this.FirstRecord, CanExecute);
}
private void FirstRecord()
{
//do whatever you want
}
private bool CanExecute()
{
return true;
}
private void Module1_IsActiveChanged(object sender, EventArgs e)
{
//Find if your window is acive
// if it is active Module1Firstrecord.IsActive = true
//else false.
}
}
With IActiveAware you can handle the active window scenario easily. According to whether your active module have a handler for the command on not the buttons will enable/disable.
I'm just switching a project across to mvvmlight and trying to do things "the right way"
I've got a simple app with a listbox
When an item is selected in the listbox, then I've hooked up a RelayCommand
This RelayCommand causes a call on an INavigationService (http://geekswithblogs.net/lbugnion/archive/2011/01/06/navigation-in-a-wp7-application-with-mvvm-light.aspx) which navigates to a url like "/DetailPage.xaml?DetailId=12"
The DetailPage.xaml is then loaded and ... this is where I'm a bit unsure...
how should the DetailPage get hooked up to a DetailView with DetailId of 12?
should I do this in Xaml somehow using a property on the ViewLocator?
should I do this in the NavigatedTo method?
Please feel free to point me to a full sample - sure this has been done a (hundred) thousand times before, but all the blogs and tutorials seem to be skipping this last trivial detail (focussing instead on the messaging and on the ioc on on the navigationservice)
Thanks!
The only place you can retrieve the URL parameter is in the view. So since your view is likely depending on it, you should fetch it in the OnNavigatedTo method.
Then, you should pass it along to your viewmodel, either using messaging (to expensive if you ask me), or by referring to your datacontext (which is the viewmodel I presume), and execeuting a method on that.
private AddTilePageViewModel ViewModel
{
get
{
return DataContext as AddTilePageViewModel;
}
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
var postalCode = NavigationContext.TryGetKey("PostalCode");
var country = NavigationContext.TryGetStringKey("Country");
if (postalCode.HasValue && string.IsNullOrEmpty(country) == false)
{
ViewModel.LoadCity(postalCode.Value, country);
}
base.OnNavigatedTo(e);
}
I'm using some special extensions for the NavigationContext to make it easier.
namespace System.Windows.Navigation
{
public static class NavigationExtensions
{
public static int? TryGetKey(this NavigationContext source, string key)
{
if (source.QueryString.ContainsKey(key))
{
string value = source.QueryString[key];
int result = 0;
if (int.TryParse(value, out result))
{
return result;
}
}
return null;
}
public static string TryGetStringKey(this NavigationContext source, string key)
{
if (source.QueryString.ContainsKey(key))
{
return source.QueryString[key];
}
return null;
}
}
}
Create a new WindowsPhoneDataBound application, it has an example of how to handle navigation between views. Basically you handle the navigation part in your view, then set the view's DataContext accord to the query string. I think it plays nicely with the MVVM pattern since your ViewModels don't have to know anything about navigation (which IMO should be handled at the UI level).
I have a simple user control in Windows Phone 7 and I want to get access to the querystring collection from the user controls Constructor. I have tried many ways and cannot seem to get acess to the containing XAML's querystring collection.
Essentially I am navigating to the page and the my user control is going to access the querystring value to write the value back to the interface.
Am I missing adding an assembly or reference or something?
I am not sure you should be trying to get at the information from the page's constructor, as it won't necessairly get called every time you land on this page. A better approach is to override the OnNavigatedTo method inherited from PhoneApplicationPage. Looking a little more carefully at your question, you may be trying to do this within a control embedded in the page, in which case you need to get at the Page in order to obtain the navigation information.
Regardless, the NavigationContext property from the page has a QueryString parameter that you can use to access the information you're after.
The following example assumes I have a parameter named "Message" in the query string when navigating to this page:
public partial class MyPage : PhoneApplicationPage
{
// Constructor
public MyPage()
{
InitializeComponent();
}
protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
base.OnNavigatedTo(e);
String navigationMessage;
if (NavigationContext.QueryString.TryGetValue("Message", out navigationMessage))
{
this.textBlock1.Text = navigationMessage;
}
}
}
Sorry about that - I started to get there, and thanks for the clarification. Your best bet then is to walk up the visual tree from your control to find the Page, then you can have at the NavigationContext. In my sample below, I have a button on a custom control within the page, whose click event finds the nav context and looks for a certain navigation parameter - I couldn't tell from the question or your follow-up what would drive the control to "want" to find the content of the query string.
(Note about getting info from the ctor follows the code below)
public partial class WindowsPhoneControl1 : UserControl
{
public WindowsPhoneControl1()
{
InitializeComponent();
}
private void button1_Click(object sender, RoutedEventArgs e)
{
GetTheQueryString();
}
private void GetTheQueryString()
{
var result = "No Joy";
var page = FindRootPage(this);
if (page != null)
{
if (page.NavigationContext.QueryString.ContainsKey("Param"))
{
result = page.NavigationContext.QueryString["Param"];
}
}
queryStringText.Text = result;
}
private static PhoneApplicationPage FindRootPage(FrameworkElement item)
{
if (item != null && !(item is PhoneApplicationPage))
{
item = FindRootPage(item.Parent as FrameworkElement);
}
return item as PhoneApplicationPage;
}
}
Note that this won't work from the ctor because of how Xaml works...the Xml tag drives the ctor to be called, then properties are set as indicated, then it is added as a child/item/etc in its container. If you do need to get at the context ASAP using this "walk up the tree" technique, handle the Control's Loaded event, by which time the control does have a parent and a tree that can be walked...
public WindowsPhoneControl1()
{
InitializeComponent();
Loaded += WindowsPhoneControl1_Loaded;
}
private void WindowsPhoneControl1_Loaded(Object sender, RoutedEventArgs e)
{
GetTheQueryString();
}
I would add a property to the UserControl subclass that would be set by the page in its OnNavigatedTo() method.