I have a custom class which a usercontrol has implemented as a dependency property in it's code behind.
public partial class HandControl
{
public HandControl()
{
InitializeComponent();
}
public Seat Seat
{
get
{
return (Seat)GetValue(SeatProperty);
}
set
{
SetValue(SeatProperty, value);
}
}
public static readonly DependencyProperty SeatProperty = DependencyProperty.Register("Seat", typeof(Seat), typeof(HandControl), new PropertyMetadata(null));
}
In my case I've bound the name property in that class to a label inside the usercontrols xaml.
<Label Content="{Binding Seat.Player.Name, RelativeSource={RelativeSource AncestorType={x:Type controls:HandControl}}}"/>
The view model of my window contains the property SeatTl and the xaml is binding to it:
public Seat SeatTr
{
get { return _seatTr; }
private set
{
_seatTr = value;
OnPropertyChanged();
}
}
<customControls:HandControl Grid.Row="1"
Grid.Column="3"
Seat="{Binding SeatTr}" />
However, when I change my class content (the name property) and manually raise OnPropertyChanged in my viewmodel (not the usercontrol), the label is not updated and still has the same content.
private void OnSeatChanged(Player player, SeatPosition seatPosition)
{
//... doing the changes ...\\
OnPropertyChanged("SeatTr");
}
Whats my problem? Anyone got a clue?
I think u should raise OnPropertyChanged for Seat.Player.Name property as It is being chaged.
Related
I have created a custom control CustomTextBox inherited from TextBox class. I have created a dependency property named CustomTextProperty.
I have binded this DP with my Viewmodel property.
While Registering the DP i have given the property change callback but it is only get called one time when my control gets the binded data initially when my xaml loads.
When i try to set my control from view the binded VM property setter does not gets called and also the propertychangecallback not gets fired.
Please help!!
Code snipet below:
My Custom control
class CustomTextBox : TextBox
{
public static readonly DependencyProperty CustomTextProperty = DependencyProperty.Register("CustomText",
typeof(string), typeof(CustomTextBox),
new FrameworkPropertyMetadata("CustomTextBox",
FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
new PropertyChangedCallback(OnCustomPropertyChange)));
public string CustomText
{
get { return (string)GetValue(CustomTextProperty); }
set { SetValue(CustomTextProperty, value); }
}
private static void OnCustomPropertyChange(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
// This is Demo Application.
// Code to be done Later...
}
}
My View Model:
public class ViewModel : INotifyPropertyChanged
{
private string textForTextBox;
public string TextForCustomTextBox
{
get
{
return this.textForTextBox;
}
set
{
this.textForTextBox = value;
this.OnPropertyChange("TextForCustomTextBox");
}
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChange(string name)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(name));
}
}
}
My Xaml Code with Binding:
<custom:CustomTextBox x:Name="CustomTextBox"
CustomText="{Binding TextForCustomTextBox, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
Grid.Row="1" HorizontalAlignment="Center" Width="200" Height="50" />
My Code Behind to set DataContext:
// My View Constructor
public View1()
{
InitializeComponent();
this.DataContext = new ViewModel();
}
You said that you declared a CustomText DependencyProperty and data bound it to your view model TextForCustomTextBox property and that much is correct. However, when you said that you tried to set your property from the view, you were mistaken.
What you were actually doing was setting the CustomTextBox .Text property from the view and that wasn't connected to your CustomTextBox.CustomText property. You can connect them like this, although I'm not quite sure what the point of that would be:
<Views:CustomTextBox x:Name="CustomTextBox" Text="{Binding CustomText, RelativeSource={
RelativeSource Self}, UpdateSourceTrigger=PropertyChanged}" CustomText="{Binding
TextForCustomTextBox, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
Grid.Row="1" HorizontalAlignment="Center" Width="200" Height="50" />
Try setting your DataContext BEFORE the actual initialization so it is available when the form/control objects are created. If it can't find before, is that what may be causing the failed bindings.
I have a Xaml Page With A textbox And a button When the User Clicks the Button The text box value should be passed to its viewModel. How to achieve this?
xaml:
<TextBox Text={Binding TextBoxAContent} />
<Button Command={Binding ButtonCommand} />
view model code should be something like this:
class MainPageViewModel : ViewModelBase
{
private string _textBoxAContent;
public string TextBoxAContent
{
get {return _textBoxAContent;}
set {
_textBoxAContent = value;
RaisePropertyChanged("TextBoxAContent");
}
}
public ICommand ButtonCommand
{
get
{
return new RelayCommand(ProcessTextHandler);
}
}
private void ProcessTextHandler()
{
//add your code here. You can process your textbox`s text using TextBoxAContent property.
}
}
You should also assign your viewmodel to view via DataContext property of the view control. (simply in constructor)
public MainPage()
{
DataContext = new MainPageViewModel();
}
UPD
p.s. RelayCommand & ViewModelBase - classes from MVVM Light
I want to bind a TextBox in the window to a property contained within a class that is a variable of the viewmodel and ensure that INotifyPropertyChanged's PropertyChanged event propagates from the class to the parent.
Let me illustrate with an example:
(Window's DataContext is set to an instance of ViewModel)
public class ViewModel {
private OtherClass classInstance = new OtherClass();
public int Attribute {
get { return classInstance.Attribute; }
}
}
public class OtherClass : INotifyPropertyChanged {
private int _attribute;
public int Attribute {
get { return _attribute; }
set {
_attribute = value;
PropertyChanged("Attribute");
}
}
...
}
The problem in this example is that, when Attribute changes, the bound Textbox does not update the binding since I assume it's listening to the ViewModel's PropertyChanged event and not that of the instance of OtherClass.
Any ideas on how to remedy this situation? I was thinking about chaining OtherClass's INotifyPropertyChanged to that of its parent, but there has to be a better way.
Why not bind directly to the class property instead of using a proxy?
public class ViewModel {
private OtherClass classInstance = new OtherClass();
public OtherClass MyOtherClass {
get { return classInstance; }
}
}
Then in your binding you can simply reference the property via the SubClass
{Binding MyOtherClass.Attribute}
A drop dead simple example, but it works!
The Code Behind:
public partial class MainWindow : Window {
private readonly SomeClass _someClass = new SomeClass();
public MainWindow() {
InitializeComponent();
DataContext = _someClass;
}
}
public class SomeClass: INotifyPropertyChanged {
private readonly SomeSubClass _mySubClass = new SomeSubClass();
public SomeSubClass MySubClass {
get { return _mySubClass; }
}
private String _name;
public String Name {
get { return _name; }
set {
_name = value;
OnPropertyChanged("Name");
}
}
//Property Change Stuff
}
public class SomeSubClass : INotifyPropertyChanged {
private String _name;
public String Name {
get {
return _name;
}
set {
_name = value;
OnPropertyChanged("Name");
}
}
//Property Change Stuff
}
The XAML:
<Window x:Class="JWC.Examples.WPF.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow">
<StackPanel>
<Label Content="Name" VerticalAlignment="Top" />
<TextBox Text="{Binding Name}" />
<Label Content="SubClass.Name" />
<TextBox Text="{Binding MySubClass.Name}" />
<Label Content="Bound to Name" />
<TextBlock Text="{Binding Name}" />
<Label Content="Bound to MySubClass.Name" />
<TextBlock Text="{Binding MySubClass.Name}" />
</StackPanel>
</Window>
You will need to do something like this:
public class ViewModel {
public ViewModel() {
classInstance = new OtherClass();
classInstance.PropertyChanged += HandleAttributeChanged;
}
private void HandleAttributeChanged(object Sender, NotifyPropertyChangedEventArgs args) {
PropertyChanged("Attribute");
}
}
I don't show it here, but you should also implement IDisposable and unsubscribe from the PropertyChanged event on your child, otherwise you will leak memory.
Alternatively you can expose the classInstance as a public property and set your binding to: ViewModel.classInstance. Note this needs to be a property and not the field itself.
I think the parent class should subscribe to the child propertyCahnged event..something like:
public class ViewModel
{
private OtherClass classInstance = new OtherClass();
public ViewModel()
{
classInstance.PropertyChanged += NotifyChildAttributeChanged;
}
public int Attribute
{
get { return classInstance.Attribute; }
}
}
NotifyChildAttributeChanged is basically a method that listens only to the "Attribute" property and fires a PropertyChanged notification of its own..
Of course our parent class must implement INotifyPropertyChanged as well as will all ViewModels (preferably) and your DataContext will detect the change.
To get around this you need to implement INotifyPropertyChanged on your view model as well. Just add the interface and the event and the rest will take care of itself - no need to chain the events / calls together.
Check out this for using reflection to get the property as well.
http://tsells.wordpress.com/2011/02/08/using-reflection-with-wpf-and-the-inotifypropertychanged-interface/
I have an ObservableCollection of "Layouts" and a "SelectedLocation" DependencyProperty on a Window. The SelectedLocation has a property called "Layout", which is an object containing fields like "Name" etc. I'm trying to bind a combobox to the SelectedLayout but it's not working.
The following does not work, I've tried binding to SelectedItem instead to no avail. I believe it may be something to do with the fact that I'm binding to a subProperty of the SelectedLocation DependencyProperty (though this does implement INotifyPropertyChanged.
<ComboBox Grid.Row="2" Grid.Column="0" x:Name="cboLayout" ItemsSource="{Binding Layouts,ElementName=root}" SelectedValue="{Binding SelectedLocation.Layout.LayoutID,ElementName=root}" DisplayMemberPath="{Binding Name}" SelectedValuePath="LayoutID" />
However, the following works (Also bound to the "SelectedLocation" DP:
<TextBox Grid.Row="4" Grid.Column="1" x:Name="txtName" Text="{Binding SelectedLocation.Name,ElementName=root,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" />
What type property Layouts has? I suppose something like this this: IEnumerable<Layout>.
But you bind selected value to Layout.LayoutID. So you got situation, when combo box contains Layout objects, and you try to select it by Int identifier. Of course binding engine can't find any Int there.
I have no idea about details of your code, so one thing I could propose: try to reduce your binding expression: SelectedItem="{Binding SelectedLocation.Layout,ElementName=root}.
If no success, provide more code to help me understand what's going on.
====UPDATE====
As I've said, you are obviously doing something wrong. But I am not paranormalist and couldn't guess the reason of your fail (without your code). If you don't want to share your code, I decided to provide simple example in order to demonstrate that everything works. Have a look at code shown below and tell me what is different in your application.
Class Layout which exposes property LayoutId:
public class Layout
{
public Layout(string id)
{
this.LayoutId = id;
}
public string LayoutId
{
get;
private set;
}
public override string ToString()
{
return string.Format("layout #{0}", this.LayoutId);
}
}
Class SelectionLocation which has nested property Layout:
public class SelectedLocation : INotifyPropertyChanged
{
private Layout _layout;
public Layout Layout
{
get
{
return this._layout;
}
set
{
this._layout = value;
this.OnPropertyChanged("Layout");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string name)
{
var safeEvent = this.PropertyChanged;
if (safeEvent != null)
{
safeEvent(this, new PropertyChangedEventArgs(name));
}
}
}
And Window class with dependency properties (actually, in my example StartupView is UserControl, but it doesn't matter):
public partial class StartupView : UserControl
{
public StartupView()
{
InitializeComponent();
this.Layouts = new Layout[] { new Layout("AAA"), new Layout("BBB"), new Layout("CCC") };
this.SelectedLocation = new SelectedLocation();
this.SelectedLocation.Layout = this.Layouts.ElementAt(1);
}
public IEnumerable<Layout> Layouts
{
get
{
return (IEnumerable<Layout>)this.GetValue(StartupView.LayoutsProperty);
}
set
{
this.SetValue(StartupView.LayoutsProperty, value);
}
}
public static readonly DependencyProperty LayoutsProperty =
DependencyProperty.Register("Layouts",
typeof(IEnumerable<Layout>),
typeof(StartupView),
new FrameworkPropertyMetadata(null));
public SelectedLocation SelectedLocation
{
get
{
return (SelectedLocation)this.GetValue(StartupView.SelectedLocationProperty);
}
set
{
this.SetValue(StartupView.SelectedLocationProperty, value);
}
}
public static readonly DependencyProperty SelectedLocationProperty =
DependencyProperty.Register("SelectedLocation",
typeof(SelectedLocation),
typeof(StartupView),
new FrameworkPropertyMetadata(null));
}
XAML of StartupView:
<UserControl x:Class="Test.StartupView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:self="clr-namespace:HandyCopy"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Name="Root">
<WrapPanel>
<ComboBox ItemsSource="{Binding Path=Layouts,ElementName=Root}"
SelectedItem="{Binding Path=SelectedLocation.Layout, ElementName=Root}"/>
</WrapPanel>
</UserControl>
Tried may approches to displaying a "no data" if there are no items in listbox. Since I'm on wp7 and using silverlight I can't use DataTriggers, so I've created a control to have it behave consistently across the whole app. BUT I if you set the breakpoint for the set method - it's not being called at all!
The control class
public class EmptyListBox : ListBox
{
public new IEnumerable ItemsSource
{
get
{
return base.ItemsSource;
}
set
{
// never here
base.ItemsSource = value;
ItemsSourceChanged();
}
}
protected virtual void ItemsSourceChanged()
{
bool noItems = Items.Count == 0;
if (noItems)
{
if (Parent is System.Windows.Controls.Panel)
{
var p = Parent as Panel;
TextBlock noData = new TextBlock();
noData.Text = "No data";
noData.HorizontalAlignment = HorizontalAlignment;
noData.Width = Width;
noData.Height = Height;
noData.Margin = Margin;
p.Children.Add(noData);
Visibility = System.Windows.Visibility.Collapsed;
}
}
}
}
This is xaml
<my:EmptyListBox ItemsSource="{Binding Path=MyData}" Name="myListBox">
<my:EmptyListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=name}" />
</DataTemplate>
</my:EmptyListBox.ItemTemplate>
</my:EmptyListBox>
Codebehind:
ClientModel ClientInfo { get; set; }
public ClientView()
{
ClientInfo = new ClientModel();
ClientInfo.PropertyChanged += new System.ComponentModel.PropertyChangedEventHandler(DataReady);
DataContext = ClientInfo
}
ClientModel class:
public class ClientModel : INotifyPropertyChanged
{
MyData _myData;
public MyData MyData
{
get
{
return _myData;
}
set
{
_myData = value;
NotifyPropertyChanged("MyData");
}
}
public void GetClient(int id)
{
// fetch the network for data
}
}
LINK TO SOLUTION .ZIP THAT SHOWS THE PROBLEM
http://rapidshare.com/files/455900509/WindowsPhoneDataBoundApplication1.zip
Your new ItemSource should be a DependencyProperty.
Anything that is working with Bindings have to be a DependencyProperty.
Simply make it a DependencyProperty.
I think the solution I'd go for is something like this:
Define a new visual state group ItemsStates and two visual states: NoItems and HasItems.
In the ControlTemplate for your custom listbox, add the visual tree for your "no data" state.
In the NoItems state, set the Visibility of your "no data" elements to Visible and set the Visibility of the default ItemsPresenter to Collapsed.
In the HasItems state, swap the Visibility of these elements.
In an OnApplyTemplate override switch to the Empty state by default: VisualStateManager.GoToState(this, "Empty", true);
In an OnItemsChanged override, check whether the items source is empty and use VisualStateManager to switch between these states accordingly.
That should work :)
Create ItemsSource as a DependencyProperty.
Example:
public IEnumerable ItemsSource
{
get { return (IEnumerable)base.GetValue(ItemsSourceProperty); }
set { base.SetValue(ItemsSourceProperty, value); }
}
public static DependencyProperty ItemsSourceProperty =
DependencyProperty.Register(
"ItemsSource",
typeof(IEnumerable),
typeof(EmptyListBox),
new PropertyMetadata(null));
try to implement the INotifyPropertyChanged interface and use for ItemsSource an ObservableCollection. In the Setter of your Property just call the OnPropertyChanged method.
Maybe this will help.
Try adding Mode=TwoWay to the ItemsSource binding:
<my:EmptyListBox ItemsSource="{Binding Path=MyData, Mode=TwoWay}" Name="myListBox">
<my:EmptyListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=name}" />
</DataTemplate>
</my:EmptyListBox.ItemTemplate>
</my:EmptyListBox>