I'm using ViewModel-first aprroach. In MainWindow.xaml I've set ContentControl where I display my UserControls (Views), by a click on a MenuItem. When I click to display UserControl first time, everything works fine.
But when I click same MenuItem to open It once again, my UserControl displays again but doesn't get loaded anymore, resulting in not having refreshed bindings. Setting my ContentControl's Content to null doesn't resolve issue.
My whole setup is like this:
1.) App.xaml resource
<!--DataContext for MainWindow.xaml-->
<ViewModels:MainWindowViewModel x:Key="Main_VM"/>
<!--DataTemplate for UserControl-->
<DataTemplate DataType="{x:Type ViewModels:MyViewModel}">
<Views:MyView />
</DataTemplate>
2.) MainWindow.xaml, where my ContenControl is located
<Window x:Class="My.Views.MainWindowView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
DataContext="{StaticResource Main_VM}">
<Grid>
<!--Menu which opens view on command-->
<Menu VerticalAlignment="Top" IsMainMenu="True" >
<MenuItem Header="My View" Command="{Binding Show_View}" CommandParameter="1"/>
</Menu>
<ContentControl Content="{Binding Display_View}" />
<!--And all other controls, like Menu for opening views on click...-->
</Grid>
</Window>
3.) ViewModel for Mainwindow.xaml (inherited from BaseViewModel)
public class MainWindowViewModel : BaseViewModel
{
public MainWindowViewModel()
{
//Command for displaying Views
Show_View = new Relay_Command(Open_view, null);
}
public ICommand Show_View { get; set; }
private BaseViewModel _display_view;
public BaseViewModel Display_View
{
get { return _display_view; }
set { _display_view = value; OnPropertyChanged(); }
}
private void Open_view(object parameter)
{
Display_View = null; //This doesn't help at all!!!
switch (parameter)
{
case "1":
Display_View= new MyViewModel();
break;
}
}
}
4.) And my UserControl.xaml
<UserControl x:Class="MyProject.Views.MyView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:ei="clr-namespace:Microsoft.Expression.Interactivity.Core;assembly=Microsoft.Expression.Interactions"
mc:Ignorable="d"
d:DesignHeight="450"
d:DesignWidth="800">
<!--Event-->
<i:Interaction.Triggers>
<i:EventTrigger EventName="Loaded">
<!--Calling a method on Load (firing only first tme !!)-->
<ei:CallMethodAction MethodName="MethodForRetrievingData" TargetObject="{Binding}" />
</i:EventTrigger>
</i:Interaction.Triggers>
<Grid>
<!--Controls in UserControl for binding etc...-->
</Grid>
</UserControl>
I've tried debugging, but as told, Loaded event of UserControl happens only once. I'm out of ideas on this one, looks like my design has a flaw.
What could be a problem here, maybe I'm missing something like NotifyProperty on UserControl itself?
You need to actually unload the view for it to be loaded again. Setting the source property of the ContentControl's Content property to null just before setting it to another MyViewModel won't unload the view. The DataTemplate is "cached".
Why don't you call the MethodForRetrievingData from the view model itself instead of relying on the view raising a Loaded event? You may for example initialize it asynchronously.
Instead of displaying a MyViewModel object content using template, try display a MyView content instead.
So you would have
private MyView _display_view;
public MyView Display_View
{
get { return _display_view; }
set { _display_view = value; OnPropertyChanged(); }
}
private void Open_view(object parameter)
{
Display_View = null; //This doesn't help at all!!!
switch (parameter)
{
case "1":
Display_View= new MyView(); // Or assign a view model here: {DataContext=new MyViewModel()}
break;
}
}
Related
I get this error:- System.NullReferenceException: 'Object reference not set to an instance of an object.'
objectPlacement was null.
private void Button_Click(object sender, RoutedEventArgs e)
{
ObjectPlacement w = new ObjectPlacement() {Topmost = };// ObjectPlacement is new WPF window
objectPlacement.WindowStyle = WindowStyle.None;
settingpanel.Children.Add(objectPlacement);//settingpanel stack is panel name
w.Show();
}
It would be much more usual to define a usercontrol or datatemplate for whatever you're trying to show in your window. A window is a kind of content control. One way to think of a window ( or contentcontrol ) is something that shows you some UI. All the UI in a window is that content.
When you add window to a project it is templated out with a grid in it.
This is the content and everything you want to see in that window goes in it.
You could replace that grid with something else instead.
If you made that a contentpresenter then you can bind or set what that'll show to some encapsulated re-usable UI.
Usually the best way to encapsulate re-usable UI is as a usercontrol.
A datatemplate can reference a usercontrol.
It is not usually your entire UI for a window you want to switch out. But you can and that is occasionally useful - say if you want a generic way to show dialogs.
The usual way to write wpf is mvvm so most devs will want some mvvm way of switching out UI.
I'll show you some code might make the description clearer.
There are some corners cut in what follows, so this is illustrative. Don't just run with this for your next lead developer interview at a stock traders.
But, basically you click a button for Login you "navigate" to a LoginUC view. Click a button for User and you "navigate" to UserUC.
My mainwindow.
<Window.Resources>
<DataTemplate DataType="{x:Type local:LoginViewModel}">
<local:LoginUC/>
</DataTemplate>
<DataTemplate DataType="{x:Type local:UserViewModel}">
<local:UserUC/>
</DataTemplate>
</Window.Resources>
<Window.DataContext>
<local:MainWindowViewModel/>
</Window.DataContext>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="100"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<ItemsControl ItemsSource="{Binding NavigationViewModelTypes}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button Content="{Binding Name}"
Command="{Binding DataContext.NavigateCommand, RelativeSource={RelativeSource AncestorType={x:Type Window}}}"
CommandParameter="{Binding VMType}"
/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
<ContentPresenter Grid.Column="1"
Content="{Binding CurrentViewModel}"
/>
</Grid>
</Window>
Notice the datatemplates which associate the type of a viewmodel with a usercontrol.
https://learn.microsoft.com/en-us/dotnet/desktop/wpf/data/data-templating-overview?view=netframeworkdesktop-4.8
What will happen is you present your data in a viewmodel to the UI via that contentpresenter and binding. That viewodel is then templated out into UI with your viewmodel as it's datacontext. The datacontext of a UserUC view will therefore be an instance of UserViewModel. Change CurrentViewModel to an instance of LoginViewModel and you get a LoginUC in your mainwindow instead.
The main viewmodel.
public class MainWindowViewModel : INotifyPropertyChanged
{
public string MainWinVMString { get; set; } = "Hello from MainWindoViewModel";
public ObservableCollection<TypeAndDisplay> NavigationViewModelTypes { get; set; } = new ObservableCollection<TypeAndDisplay>
(
new List<TypeAndDisplay>
{
new TypeAndDisplay{ Name="Log In", VMType= typeof(LoginViewModel) },
new TypeAndDisplay{ Name="User", VMType= typeof(UserViewModel) }
}
);
private object currentViewModel;
public object CurrentViewModel
{
get { return currentViewModel; }
set { currentViewModel = value; RaisePropertyChanged(); }
}
private RelayCommand<Type> navigateCommand;
public RelayCommand<Type> NavigateCommand
{
get
{
return navigateCommand
?? (navigateCommand = new RelayCommand<Type>(
vmType =>
{
CurrentViewModel = null;
CurrentViewModel = Activator.CreateInstance(vmType);
}));
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged([CallerMemberName] String propertyName = "")
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
Type and display relates the type for a viewmodel with text displayed in the UI.
public class TypeAndDisplay
{
public string Name { get; set; }
public Type VMType { get; set; }
}
This is "just" quick and dirty code to illustrate a principle which is usually called viewmodel first navigation. Google it, you should find a number of articles explaining it further.
For completeness:
<UserControl x:Class="wpf_Navigation_ViewModelFirst.LoginUC"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:wpf_Navigation_ViewModelFirst"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<StackPanel Background="Yellow">
<TextBlock Text="This is the Login User Control"/>
<TextBox>
<TextBox.InputBindings>
<KeyBinding Key="Return" Command="{Binding LoginCommand}"/>
</TextBox.InputBindings>
</TextBox>
</StackPanel>
</UserControl>
public class LoginViewModel
{
private RelayCommand loginCommand;
public RelayCommand LoginCommand
{
get
{
return loginCommand
?? (loginCommand = new RelayCommand(
() =>
{
string s = "";
}));
}
}
}
<UserControl x:Class="wpf_Navigation_ViewModelFirst.UserUC"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:wpf_Navigation_ViewModelFirst"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid Background="pink">
<TextBlock Text="This is the User module Control"
VerticalAlignment="Top"
/>
<TextBlock Text="{Binding Path=DataContext.MainWinVMString, RelativeSource={RelativeSource AncestorType={x:Type Window}}}"
VerticalAlignment="Bottom"
/>
</Grid>
</UserControl>
public class UserViewModel
{
}
I put this together some years ago, I would now recommend the community mvvm toolkit with it's code generation, base classes, messenger etc.
In a user control I have context menu for data grid like shown below
<DataGrid.ContextMenu>
<ContextMenu Focusable="False">
<menuItems:ExportMenuItemView DataContext="{Binding ExportMenuItemVM}"/>
</ContextMenu>
</DataGrid.ContextMenu>
in the view model class I have the view property
public ExportMenuItemViewModel ExportMenuItemVM {get;set;}
ExportMenuItemView is a user control which contains a menu item
<UserControl x:Class="MenuControl.View.ExportMenuItemView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="20" d:DesignWidth="200">
<MenuItem Header="Export" Focusable="False" Command="{Binding Export}"/>
</UserControl>
Below is the view model class for the Export View
namespace MenuControl.ViewModel
{
[AddINotifyPropertyChangedInterface]
public class ExportMenuItemViewModel : ViewModelBase
{
public ExportBlockMenuItemViewModel(IExport exporter)
{
Export = new RelayCommand(() => exporter.Export());
}
public RelayCommand Export { get; set; }
}
}
RelayCommand Export is not getting executed when I click the menu item "Export". I am using MVVLLight
I think you are missing something related to the DataContext Binding in your xaml like :
<UserControl x:Class="MenuControl.View.ExportMenuItemView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="20" d:DesignWidth="200"
DataContext="{Binding Main, Source={StaticResource Locator}}">
<MenuItem Header="Export" Focusable="False" Command="{Binding Export}"/>
</UserControl>
ViewModels in ViewModelLocator MVVM Light
Found solution
I need to create a separate function. If I call the operation as a lambda function as shown below, it is not working
Export = new RelayCommand(() => exporter.Export());
I need to create a function "foo" and give that in the relay command like shown below. I do know the reason but when I change the code as below, it started working
Export = new RelayCommand(foo);
private void foo()
{
exporter.Export()
}
I am trying to using mvvm pattern with wpf to create an interface for a project previously did in win form.
In this project i have an object that contains some List<> that i have to show in real time on my interface with a combobox, the problem is that combobox don't change his values. I'm using the dll of mvvm fundation for implement NotifyPropertyChanged. I think to make some mistake but i don'y know where is it.
I've tried to do a simple code with only one list in viewmodel and without a model but the result doesn't change.
<Window x:Class="ProvaComboBox.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:ProvaComboBox"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Grid>
<Grid.DataContext>
<local:ViewModel />
</Grid.DataContext>
<Button Content="Generate" Command="{Binding Generate}"/>
<Button Content="Clear" Command="{Binding Clear}"/>
<ComboBox ItemsSource="{Binding Path=Word, Mode=OneWay}" />
</Grid>
</Window>
//view Model
class ViewModel:ObservableObject
{
private List<string> _word;
public List<string> Word
{
get { return _word; }
}
public ViewModel()
{
_word = new List<string>();
}
public ICommand Generate
{ get { return new RelayCommand(GenerateExecute); } }
void GenerateExecute()
{
_prova.Add("pippo");
_prova.Add("pluto");
RaisePropertyChanged("Word");
}
public ICommand Clear
{ get { return new RelayCommand(ClearExecute); } }
void ClearExecute()
{
_prova.Clear();
RaisePropertyChanged("Word");
}
}
//View:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
}
I think that the problem it's RaisePropertyChanged, but it work correctly with normal variables.
I've tryed also using ObservableCollection and it work, but i can't use it with real project.
(p.s. Its my first question in stack overflow, sorry if i did some mistake!)
use ObservableCollection like that
public ObservableCollection<string> Word
{
get => _word;
set
{
_word= value;
RaisePropertyChanged("Word");
}
}
and change the binding mode in your combobox xaml code from OneWay to TwoWay or just remove it to be something like
<ComboBox ItemsSource="{Binding Path=Word}" />
I am newbie in XAML Databinding and I am stuck in this situation. I am using Mahapps MetroWindow.
Suppose that I have a UserControl named usrctrl_Camera_Control. I have a simple button there. The C# code is given below.
namespace TA141501005
{
public partial class usrctrl_Camera_Control : UserControl
{
public usrctrl_Camera_Control()
{
this.DataContext = this;
InitializeComponent();
}
}
The XAML is given below
<UserControl
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:Custom="http://metro.mahapps.com/winfx/xaml/controls" xmlns:local="clr-namespace:TA141501005" x:Class="TA141501005.usrctrl_Camera_Control"
mc:Ignorable="d"
d:DesignHeight="768" d:DesignWidth="1366" Background="#FF2B2B2B" Height="738" Width="1336">
<UserControl.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="/Resources/Icons.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</UserControl.Resources>
<Grid>
<Button x:Name="btn_Test" Content="Button" Grid.Column="1" HorizontalAlignment="Left" Margin="472,59,0,0" VerticalAlignment="Top" Width="75" Grid.RowSpan="2" IsEnabled="{Binding Path=IsNyetEnabled, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}}" />
</Grid>
The C# code for MainWindow is given below.
namespace TA141501005
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : MetroWindow
{
usrctrl_Camera_Control usrctrl_camera_control;
public bool IsNyetEnabled { get; set; }
public MainWindow()
{
IsNyetEnabled = false;
this.DataContext = this;
InitializeComponent();
usrctrl_camera_control = new usrctrl_Camera_Control();
}
}
}
and the XAML code for MainWindow is given below.
<Controls:MetroWindow x:Class="TA141501005.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:Controls="clr-namespace:MahApps.Metro.Controls;assembly=MahApps.Metro"
Title="Macromium System Control V1.0ES - TA141501005 [Engineering Sample]" Height="768" Width="1366" Background="#FF2B2B2B" ScrollViewer.VerticalScrollBarVisibility="Disabled" ResizeMode="NoResize" WindowStyle="ThreeDBorderWindow" WindowStartupLocation="CenterScreen" IsMinButtonEnabled="False" IsWindowDraggable="False" ShowMaxRestoreButton="False" ShowMinButton="False" ShowSystemMenuOnRightClick="False" IconOverlayBehavior="Flyouts">
<Window.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="/Resources/Icons.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Window.Resources>
<Grid>
<Button x:Name="btn_test" Content="Button" HorizontalAlignment="Left" Margin="589,590,0,0" VerticalAlignment="Top" Width="75" IsEnabled="{Binding IsNyetEnabled}"/>
</Grid>
I want to binding the property IsEnabled in btn_test in usrctrl_Camera_Control and btn_test in MainWindow into IsNyetEnabled in MainWindow. I set the IsNyetEnabled into false before I do InitializeComponent() in MainWindow.
The binding between btn_test.IsEnabled in MainWindow into IsNyetEnabled in MainWindow is done flawlessly. The btn_test in MainWindow is no longer enabled. (I know, I need to implement INotifyPropertyChanged to notify the subsriber if there is any change but for now, just leave it as is for simplicity).
But, the binding between btn_test.IsEnabled in usrctrl_Camera_Control into IsNyetEnabled in MainWindow is failed. I have used Visual Studio "Create Data Binding" wizard but it always return error when compiling.
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='TA141501005.MainWindow', AncestorLevel='1''. BindingExpression:Path=IsNyetEnabled; DataItem=null; target element is 'Button' (Name='btn_Test'); target property is 'IsEnabled' (type 'Boolean')
Do you have any suggestion? I have tried for whole day without a luck.
Is there any way to access parent datacontext without removing this.Datacontext = this?
Looking forward for your suggestion and explanation.
Thank you very much.
Edit.
I display my UserControl via Flyout.
Window parentWindow = Window.GetWindow(this);
object obj = parentWindow.FindName("mainFlyout");
Flyout flyout = (Flyout) obj;
flyout.Content = new SomeFlyOutUserControl();
flyout.IsOpen = !flyout.IsOpen;
Create the IsNyetEnabled property as a dependency property on the MainForm. This is the mechanism that will propagate changes in WPF
Example:
public static readonly DependencyProperty IsNyetEnabledProperty =
DependencyProperty.Register("IsNyetEnabled", typeof(bool),
typeof(MainWindow),new FrameworkPropertyMetadata(false));
public bool IsNyetEnabled
{
get { return (bool)GetValue(MainWindow.IsNyetEnabled); }
set { SetValue(MainWindow.IsNyetEnabled, value); }
}
To that you can bind your Button in the MainWindow directly.
For the UserControl though we have to add a shim, because the UserControl won't be able to find the ancestor when you create it.
Create on your UserControl like Moez posted another DependencyProperty:
public static readonly DependencyProperty IsButtonEnabledProperty =
DependencyProperty.Register("IsButtonEnabled", typeof(bool),
typeof(usrctrl_Camera_Control),new FrameworkPropertyMetadata(false));
public bool IsButtonEnabled
{
get { return (bool)GetValue(usrctrl_Camera_Control.IsButtonEnabledProperty); }
set { SetValue(usrctrl_Camera_Control.IsButtonEnabledProperty, value); }
}
Bind your UserControl button IsEnabled property to that.
Now as a last step we will have to connect the two Dependency Properties when you create your UserControl.
<local:usrctrl_Camera_Control x:Name="yourControl" ...Whatever else... IsButtonEnabled="{Binding Path=IsNyetEnabled, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}} />
This should work now.
I suggest you use DependencyProperty :
public static readonly DependencyProperty IsButtonEnabledProperty = DependencyProperty.Register(
"IsButtonEnabled", typeof(bool), typeof(UserControl1), new PropertyMetadata(default(bool)));
public bool IsButtonEnabled
{
get { return (bool)GetValue(IsButtonEnabledProperty); }
set { SetValue(IsButtonEnabledProperty, value); }
}
// Here Rename your UserControl To Test
<Grid>
<Button x:Name="btn_Test" Content="Button" Grid.Column="1" HorizontalAlignment="Left" Margin="472,59,0,0" VerticalAlignment="Top" Width="75" Grid.RowSpan="2" IsEnabled="{Binding Path=IsButtonEnabled, ElementName=Test}"}" />
</Grid>
As #Frank J suggested, I modify his last step.
I create the usercontrol during runtime, not from the XAML. Therefore it would be look like this for the last step.
usrctrl_camera_control = new usrctrl_Camera_Control();
Binding b = new Binding("IsNyetEnabled");
b.Source = this;
b.Mode = BindingMode.OneWay;
usrctrl_camera_control.SetBinding(usrctrl_Camera_Control.IsButtonEnabledProperty, b);
Thanks all.. I hope it would be useful for those who have the same problem with me.
I'm still pretty new to WPF and I decided to change the application I am developing to start following the MVVM pattern as best as I could. I am running into a problem when I try to have a list box dictate the view model of a content control. I've been stuck on this for a while and searching the internet is not producing answers for me.
For some reason a new instance of the view model the list box contains is being generated as the data context of the content control. When I was debugging I made sure that the list box contains the view models it should, and that the item I select on the list box is indeed the item that the list box is selecting, however the content control changing based on the selection. There is a view model populating the content control, however it is not in the collection the list box populates from. And I can somehow delete the view model in the content control via my remove button. But when I make a selection change on the list box, or add a new item to the collection it populates the content control with a new view model that once again is not in the collection. I have no clue why it is doing this, or what in my code would suggest this behavior.
I made a simple application to try and figure out what I'm doing wrong. It replicates my problem perfectly. I'm pretty sure the buttons don't adhere to MVVVM (supposed to run a command contained in the view model to adhere to MVVM from what I've been reading) but that is not my main concern right now as the problem exists without the buttons.
MainWindow.xml
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication1" x:Class="WpfApplication1.MainWindow"
Title="MainWindow" Height="440" Width="436">
<Window.DataContext>
<local:mwvm/>
</Window.DataContext>
<Window.Resources>
<DataTemplate DataType="{x:Type local:ucvm}">
<local:uc/>
</DataTemplate>
</Window.Resources>
<Grid>
<Button Content="a" HorizontalAlignment="Left" Margin="323,351,0,0" VerticalAlignment="Top" Width="95" Click="Button_Click"/>
<Button Content="r" HorizontalAlignment="Left" Margin="323,378,0,0" VerticalAlignment="Top" Width="95" Click="Button_Click_1"/>
<ContentControl Margin="10,10,110,10" Content="{Binding SelectedItem, ElementName=lb_UCs}"/>
<ListBox x:Name="lb_UCs" HorizontalAlignment="Left" Height="336" Margin="323,10,0,0" VerticalAlignment="Top" Width="95" ItemsSource="{Binding UCs}" DisplayMemberPath="CoolText"/>
</Grid>
</Window>
MainWindow.xaml.cs
public partial class PanelPartsView : UserControl
{
private PanelPartsViewModel _DC;
public PanelPartsView()
{
InitializeComponent();
_DC = DataContext as PanelPartsViewModel;
}
private void btn_Remove_Click(object sender, RoutedEventArgs e)
{
_DC.Panels.Remove(lb_Panels.SelectedItem as PartsViewModel);
}
private void btn_Add_Click(object sender, RoutedEventArgs e)
{
var pvm = new PartsViewModel();
_DC.Panels.Add(pvm);
lb_Panels.SelectedItem = pvm;
System.Console.WriteLine("lb_Panels.selecteditem = {0}", ((PartsViewModel)lb_Panels.SelectedItem).PanelName);
System.Console.WriteLine("cc_PanelParts.content = {0}", ((PartsViewModel)cc_PanelParts.Content).PanelName);
}
}
mwvm
class mwvm
{
private ObservableCollection<ucvm> _UCs = new ObservableCollection<ucvm>();
public ObservableCollection<ucvm> UCs
{
get { return _UCs; }
}
public mwvm()
{
//this is for for testing, the real application would be purely dynamic
_UCs.Add(new ucvm());
_UCs.Add(new ucvm());
_UCs.Add(new ucvm());
}
}
uc.xaml
<UserControl
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:WpfApplication1" x:Class="WpfApplication1.uc"
mc:Ignorable="d" d:DesignWidth="300" Height="90">
<Grid>
<Grid.DataContext>
<local:ucvm/>
</Grid.DataContext>
<Button Content="{Binding CoolText}" Margin="10,10,10,0" Height="44" VerticalAlignment="Top"/>
<TextBox Height="23" Margin="10,59,10,0" TextWrapping="Wrap" Text="{Binding CoolText}" VerticalAlignment="Top"/>
</Grid>
</UserControl>
uc.xaml.cs
public partial class uc : UserControl
{
public uc()
{
InitializeComponent();
}
}
ucvm.cs
class ucvm : INotifyPropertyChanged
{
private static int i = 1;
private string _CoolText = "<" + i++ + ">" + System.DateTime.Now.ToLongTimeString();
public string CoolText
{
get { return _CoolText; }
set
{
_CoolText = value;
NPC("CoolText");
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void NPC(string s)
{
if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(s));
}
}
I have also tried binding the content control like so...
<ContentControl Content="{Binding SelectedUCVMl, Mode=OneWay}"/>
<ListBox x:Name="lb_UCs" ItemsSource="{Binding UCs}" SelectedItem="{Binding SelectedUCVM}" DisplayMemberPath="CoolText"/>
...and so...
<ContentControl Content="{Binding UCs/}"/>
<ListBox x:Name="lb_UCs" ItemsSource="{Binding UCs}" IsSynchronizedWithCurrentItem="True" DisplayMemberPath="CoolText"/>
but to no avail.
Any help would be greatly appreciated.
It looks like you just have to remove this part from uc.xaml:
<Grid.DataContext>
<local:ucvm/>
</Grid.DataContext>
This syntax creates a new instance of the view model, each time an instance of uc.xaml is created, which of course isn't what you want. You want the data context of uc.xaml instances to inherit the instance currently selected in the list box.