I'm following this question on how to access your DataContext class from code-behind. Implemeting it the way it says doiesn't work for me (apparently I'm doing something wrong).
What I'm trying to do:
I have a button that is trying to read a Text property from a class that is binded to TextBox:
private void myButton_Click(object sender, RoutedEventArgs e)
{
var dataContext = myWindow.DataContext as myClass;
System.Windows.MessageBox.Show(dataContext.Text);
}
For some reason dataContext is always null.
XAML:
<Window x:Class="TestApp.MainWindow"
x:Name="myWindow"
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:TestApp"
mc:Ignorable="d"
Title="MainWindow" Height="200" Width="300">
<Window.Resources>
<local:myClass x:Key="myDataSource"/>
</Window.Resources>
<Window.DataContext>
<Binding Source="myDataSource"/>
</Window.DataContext>
<Grid Margin="0,0,0,2">
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<TextBox HorizontalAlignment="Stretch" Margin="5,5,5,5" TextWrapping="Wrap" Text="{Binding Path=Text, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Stretch" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" />
<Button x:Name="myButton" Content="Button" HorizontalAlignment="Stretch" Margin="5,5,5,5" Grid.Row="1" VerticalAlignment="Stretch" Click="myButton_Click"/>
</Grid>
</Window>
Code-behind:
namespace TestApp
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
//var dataContext = myWindow.DataContext as myClass;
}
private void myButton_Click(object sender, RoutedEventArgs e)
{
var dataContext = myWindow.DataContext as myClass;
System.Windows.MessageBox.Show(dataContext.Text);
}
}
public class myClass : INotifyPropertyChanged
{
private string text;
public string Text
{
get { return text; }
set {
text = value;
OnPropertyChanged("Text");
}
}
public event PropertyChangedEventHandler? PropertyChanged;
// Create the OnPropertyChanged method to raise the event
// The calling member's name will be used as the parameter.
protected void OnPropertyChanged([CallerMemberName] string name = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}
}
}
The full code is also in this question (that was closed since it was "answered" in the question linked above, but the solution still doesn't work for me). What am I doing wrong?
The expression
<Window.DataContext>
<Binding Source="myDataSource"/>
</Window.DataContext>
binds the DataContext to the string "myDataSource". It should instead be
<Window.DataContext>
<Binding Source="{StaticResource myDataSource}"/>
</Window.DataContext>
You do however not have to declare the DataContext object as resource at all. Just write
<Window.DataContext>
<local:myClass/>
</Window.DataContext>
Also be aware that your conclusion that the "DataContext is always null" is incorrect. It is the result of the expression DataContext as myClass which was null, because DataContext did not contain an object of type myClass. In general, when you use the as operator, you should always check the result for null before accessing it. Or use the is operator like
if (DataContext is myClass dataContext)
{
MessageBox.Show(dataContext.Text);
}
You may also notice that using the myWindow field was redundant, since the code behind methods belong to the MainWindow class.
Related
I am trying to make an app using using MVVMLight that has a sidebar with buttons, each button shows a new usercontrol hosted in a ContentControl. When the user clicks the buttons in the sidebar (Show View1 / Show View2) it shows the views correctly.
My problems arise when the user has already shown a View (it could be View1 or View2 ), say View1 and click (Show View1) ** again ** View1 controls remain with the same values and I would like to show the same view with all controls as if it had restarted. (I know that I could reset all controls within the user control (View1) but my application requires having a new instance of the view every time the button is clicked).
Somehow, in the same scenario when the user is in View 1, switch to view 2 and return to view 1, a new instance is created and shown as I would like. I would like to get the same result without the need to switch to view 2 and return.
Here is a minimal reproducible example of the issue:
ViewModelLocator.cs
using CommonServiceLocator;
using GalaSoft.MvvmLight.Ioc;
namespace SidebarApp.ViewModel
{
public class ViewModelLocator
{
/// <summary>
/// Initializes a new instance of the ViewModelLocator class.
/// </summary>
public ViewModelLocator()
{
ServiceLocator.SetLocatorProvider(() => SimpleIoc.Default);
// Register viewmodels
SimpleIoc.Default.Register<MainViewModel>();
SimpleIoc.Default.Register<View1ViewModel>();
SimpleIoc.Default.Register<View2ViewModel>();
}
public MainViewModel Main { get { return ServiceLocator.Current.GetInstance<MainViewModel>(); } }
public View1ViewModel View1Vm { get { return ServiceLocator.Current.GetInstance<View1ViewModel>(); } }
public View2ViewModel View2Vm { get { return ServiceLocator.Current.GetInstance<View2ViewModel>(); } }
public static void Cleanup()
{
// TODO Clear the ViewModels
}
}
}
MainViewModel.cs
using GalaSoft.MvvmLight;
using GalaSoft.MvvmLight.Command;
using System.Windows.Input;
namespace SidebarApp.ViewModel
{
public class MainViewModel : ViewModelBase
{
// Commands
public ICommand ShowView1Command { get; private set; }
public ICommand ShowView2Command { get; private set; }
/// <summary>
/// Property that will cointain the current viewmodel to show
/// ViewModelBase inplements ObservableObject class which imlements INotifyPropertyChanged
/// </summary>
public ViewModelBase CurrentViewModel { get; set; }
/// <summary>
/// Initializes a new instance of the MainViewModel class.
/// </summary>
public MainViewModel()
{
this.ShowView1Command = new RelayCommand(ShowView1);
this.ShowView2Command = new RelayCommand(ShowView2);
}
private void ShowView1()
{
// I tried this but it doesn't work
//CurrentViewModel = null or View2ViewModel;
CurrentViewModel = new View1ViewModel();
}
private void ShowView2()
{
CurrentViewModel = new View2ViewModel();
}
}
}
MainWindow.xaml
<Window x:Class="SidebarApp.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:SidebarApp"
mc:Ignorable="d"
DataContext="{Binding Main, Source={StaticResource Locator}}"
Title="MainWindow" Height="348.965" Width="560.683">
<Window.Resources>
<DataTemplate DataType="{x:Type local:View1ViewModel}">
<local:View1View />
</DataTemplate>
<DataTemplate DataType="{x:Type local:View2ViewModel}">
<local:View2View />
</DataTemplate>
</Window.Resources>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="0.3*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<StackPanel>
<Button Command="{Binding ShowView1Command}">Show View1</Button>
<Button Command="{Binding ShowView2Command}">Show View2</Button>
</StackPanel>
<ContentControl Grid.Column="1" Content="{Binding Path=CurrentViewModel}"></ContentControl>
</Grid>
</Window>
View1View.xaml
<UserControl x:Class="SidebarApp.View1View"
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:SidebarApp"
mc:Ignorable="d"
DataContext="{Binding View1Vm, Source={StaticResource Locator}}"
d:DesignHeight="450" d:DesignWidth="800">
<Grid Background="LightPink">
<StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
<TextBlock HorizontalAlignment="Center" Text="Welcome to View 1" FontSize="20"/>
<TextBox HorizontalAlignment="Stretch" Text="Original text value"/>
<CheckBox Content="Some boolean value"/>
</StackPanel>
</Grid>
</UserControl>
View1ViewModel.cs
using GalaSoft.MvvmLight;
namespace SidebarApp
{
public class View1ViewModel : ViewModelBase
{
public View1ViewModel()
{
}
}
}
View2View.xaml
<UserControl x:Class="SidebarApp.View2View"
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:SidebarApp"
mc:Ignorable="d"
DataContext="{Binding View2Vm, Source={StaticResource Locator}}"
d:DesignHeight="450" d:DesignWidth="800">
<Grid Background="LightCyan">
<StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
<TextBlock HorizontalAlignment="Center" Text="Welcome to View 2" FontSize="20"/>
<TextBox HorizontalAlignment="Stretch" Text="Some text in view2"/>
<Button Content="Button"/>
</StackPanel>
</Grid>
</UserControl>
View2ViewModel.cs
using GalaSoft.MvvmLight;
namespace SidebarApp
{
public class View2ViewModel : ViewModelBase
{
public View2ViewModel()
{
}
}
}
App.xaml
<Application x:Class="SidebarApp.App" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:SidebarApp" StartupUri="MainWindow.xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" d1p1:Ignorable="d" xmlns:d1p1="http://schemas.openxmlformats.org/markup-compatibility/2006">
<Application.Resources>
<ResourceDictionary>
<vm:ViewModelLocator x:Key="Locator" d:IsDataSource="True" xmlns:vm="clr-namespace:SidebarApp.ViewModel" />
</ResourceDictionary>
</Application.Resources>
</Application>
For example I enter to the view1 and change the value of the textbox ("Original text value") to another value and I click again in Show View1 the text and everything in the usercontrol stays the same but when I switch to view2 and go back to view1 a new usercontrol is shown with his original values.
This might feel like something of a workaround, but it works. Hopefully it will prove useful. (Obviously make same changes to View2View view/view model).
ViewModelLocator.cs
public View1ViewModel View1Vm { get { return new View1ViewModel(); } }
MainViewViewModel.cs
private void ShowView1()
{
CurrentViewModel = new ViewModelLocator().View1Vm;
}
View1View.xaml
<UserControl x:Class="SidebarApp.View1View"
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:SidebarApp"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800">
<Grid Background="LightPink">
<StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
<TextBlock HorizontalAlignment="Center" Text="Welcome to View 1" FontSize="20"/>
<TextBox HorizontalAlignment="Stretch" Text="{Binding Path=View1Text, Mode=TwoWay}"/>
<CheckBox Content="Some boolean value" IsChecked="{Binding Path=CheckBoxChecked, Mode=TwoWay}"/>
</StackPanel>
</Grid>
</UserControl>
View1ViewModel.cs
public class View1ViewModel : ViewModelBase
{
private string _view1Text;
private bool _checkBoxedChecked;
public string View1Text
{
get
{
return _view1Text;
}
set
{
_view1Text = value;
RaisePropertyChanged("View1Text");
}
}
public bool CheckBoxChecked
{
get
{
return _checkBoxedChecked;
}
set
{
_checkBoxedChecked = value;
RaisePropertyChanged("CheckBoxChecked");
}
}
public View1ViewModel()
{
View1Text = "Original text value";
}
}
I have a window called RolledPaper.xaml with a textblock called SequenceValue.
SequenceValue is defined in another window called CounterSettings.xaml by typing in a textbox called SequenceRequested. I would like to have SequenceValue be always in sinch with SequenceRequested.
I tryed and failed using the same datacontext for both windows.
here it is the code for RolledPaper.xaml:
<Window x:Class="Numbering3.View.RolledPaper"
WindowStyle="None"
ResizeMode="NoResize"
BorderBrush="LightGray"
BorderThickness="5"
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:Numbering3.View"
xmlns:vm="clr-namespace:Numbering3.ViewModel"
xmlns:cv="clr-namespace:Numbering3.Helper"
xmlns:vo="clr-namespace:Numbering3.ViewModel"
xmlns:sys="clr-namespace:System;assembly=mscorlib"
mc:Ignorable="d"
Title="RolledPaper" Height="750" Width="1218"
Background="{DynamicResource WindowBrush}"
DataContextChanged="Rolledpaper_DataContextChanged">
<Window.DataContext>
<vm:ViewModelRolledPaper/>
</Window.DataContext>
<TextBlock x:Name="SequenceValue" Grid.Column="3" HorizontalAlignment="Left" Height="19" Margin="72,310,0,0" TextWrapping="Wrap"
Background="White" VerticalAlignment="Top" Width="98" Text="{Binding _SequenceValueToShow.SequenceValuetoShow, Mode=TwoWay, FallbackValue=NNN, TargetNullValue=NNN, UpdateSourceTrigger=PropertyChanged}"/>
</Grid>
code behind:
public partial class RolledPaper : Window
{
public RolledPaper()
{
WindowStartupLocation = System.Windows.WindowStartupLocation.CenterScreen;
SaveKeeper.fromMain = false;
InitializeComponent();
this.MouseLeftButtonDown += delegate { this.DragMove(); };
DataContextChanged += new DependencyPropertyChangedEventHandler(Rolledpaper_DataContextChanged);
}
the CounterSetting window:
<Window x:Class="Numbering3.View.CounterSettings"
...
...
<Window.DataContext>
<ViewModelCounterSettings/>
</Window.DataContext>
<Grid Margin="0,-19,-0.4,0">
<TextBox x:Name="SequenceRequested" PreviewTextInput="SequenceValidationTextBox" MaxLength="10" HorizontalAlignment="Left" Height="23" Margin="154,324,0,0" TextWrapping="Wrap"
Text="{Binding Path=_SequenceValueToShow.SequenceValueToKeep, FallbackValue='NNN', TargetNullValue ='NNN', Mode=TwoWay, UpdateSourceTrigger=PropertyChanged }" VerticalAlignment="Top" Width="120" TextChanged="SequenceRequested_TextChanged" />
</Grid>
its code behind:
public partial class CounterSettings : Window
{
public CounterSettings()
{
InitializeComponent();
this.MouseLeftButtonDown += delegate { this.DragMove(); };
DataContextChanged += new DependencyPropertyChangedEventHandler(CounterSettings_DataContextChanged);
}
And the SequeneValue class:
public class SequenceValue : INotifyPropertyChanged
{
public string SequenceValueToKeep
{
get
{
return _sequenceValueToKeep=_sequenceProcessor.GetSequence();
}
set
{
if (_sequenceValueToKeep != value)
{
__sequenceValueToKeep = value;
RaisePropertyChanged("SequenceValueToKeep");
}
}
}
private void RaisePropertyChanged(string prop)
{
if (PropertyChanged != null)
{ PropertyChanged(this, new PropertyChangedEventArgs(prop)); }
}
public event PropertyChangedEventHandler PropertyChanged;
}
}
I need to put a value in the textbox of countersetting =>string Sequencevalue.SequenceValueToKeep is updated => textblock in RolledPaper window shows Sequencevalue.SequenceValueToKeep .
Thank you.
Solutio 1:
You can use one Static ViewModel to get the to to know each other.
in App.xaml
<Application.Resources>
...
<MainViewModel x:Key="mainViewModel" />
</Application.Resources>
and then in CounterSetting.xaml
<Window otherProperties=...
DataContext="{Binding ViewModelCounterSettings, Source={StaticResource mainViewModel}}"/>
and in RolledPaper.xaml
<Window otherProperties=...
DataContext="{Binding ViewModelRolledPaper, Source={StaticResource mainViewModel}}"/>
The MainViewModel does inits your two ViewModel and makes them accessible as properties and also gives the the same instance of SequenceValue
Solution 2:
Create an object of SequenceValue as an static resource, like
<Application.Resources>
...
<SequenceValue x:Key="sequenceValue"/>
</Application.Resources>
and set it as the DataContext of your TextBox and TextBlock
<TextBox DataContext="{StaticResource sequenceValue}"
Text="{Binding SequenceValueToKeep, FallbackValue='NNN', TargetNullValue='NNN', Mode=TwoWay, UpdateSourceTrigger=PropertyChanged }"
... />
<TextBlock DataContext="{StaticResource sequenceValue}"
Text="{Binding SequenceValuetoShow, FallbackValue=NNN, TargetNullValue=NNN, UpdateSourceTrigger=PropertyChanged}"
to keep my MainWindow.xaml.cs clean I tried to outsource everything to a ViewModel class and then bind my view to properties of my ViewModel property
However using this extra layer doesn't seem to work. My List- and Textbox just stay empty. Any way to get this method working?
MainWindow class:
public partial class MainWindow : Window, INotifyPropertyChanged
{
public ViewModel ViewModel { get; set; }
public MainWindow()
{
InitializeComponent();
ViewModel = new ViewModel();
}
}
ViewModel class:
public class ViewModel : INotifyPropertyChanged
{
private string m_oneLineOnly;
private ObservableCollection<string> m_sampleLines;
public ObservableCollection<string> SampleLines
{
get => m_sampleLines;
set
{
m_sampleLines = value;
RaisePropertyChanged(nameof(SampleLines));
}
}
public string OneLineOnly
{
get => m_oneLineOnly;
set
{
m_oneLineOnly = value;
RaisePropertyChanged(nameof(OneLineOnly));
}
}
public ViewModel()
{
SampleLines = new ObservableCollection<string>(new List<string>()
{
"Gedanken",
"Zeit",
"Sand"
});
OneLineOnly = "Hello World";
}
public event PropertyChangedEventHandler PropertyChanged = delegate { };
private void RaisePropertyChanged(string propertyName)
{
var handlers = PropertyChanged;
handlers(this, new PropertyChangedEventArgs(propertyName));
}
}
MainWindow XAML
<Window x:Class="DataContext_Test_Project.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:DataContext_Test_Project"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800"
x:Name="Window">
<Grid>
<ListBox
HorizontalAlignment="Left"
Height="100"
Margin="334,132,0,0"
VerticalAlignment="Top"
Width="100"
ItemsSource="{Binding ElementName=Window, Path=ViewModel.SampleLines}"/>
<TextBox
HorizontalAlignment="Left"
Height="23"
Margin="184,166,0,0"
TextWrapping="Wrap"
VerticalAlignment="Top"
Width="120"
DataContext="{Binding ElementName=Window, Path=ViewModel}"
Text="{Binding Path=OneLineOnly}"/>
</Grid>
You can also define the DataContext in code behind:
public partial class MainWindow : Window
{
public ViewModel ViewModel { get; set; }
public MainWindow()
{
InitializeComponent();
ViewModel = new ViewModel();
DataContext = ViewModel;
}
}
And clean your XAML:
<Grid>
<ListBox
HorizontalAlignment="Left"
Height="100"
Margin="334,132,0,0"
VerticalAlignment="Top"
Width="100"
ItemsSource="{Binding SampleLines}"/>
<TextBox
HorizontalAlignment="Left"
Height="23"
Margin="184,166,0,0"
TextWrapping="Wrap"
VerticalAlignment="Top"
Width="120"
Text="{Binding OneLineOnly}"/>
</Grid>
In order to make Bindings like
ItemsSource="{Binding ElementName=Window, Path=ViewModel.SampleLines}"
DataContext="{Binding ElementName=Window, Path=ViewModel}"
work, you have two options. Either make the ViewModel property fire a property change notification, or simply initialize it before the XAML is parsed, i.e. before InitializeComponent() is called:
Like this:
public partial class MainWindow : Window
{
public ViewModel ViewModel { get; }
public MainWindow()
{
ViewModel = new ViewModel();
InitializeComponent();
}
}
Or simpler:
public partial class MainWindow : Window
{
public ViewModel ViewModel { get; } = new ViewModel();
public MainWindow()
{
InitializeComponent();
}
}
Remove the following line from xaml.cs file : ViewModel = new ViewModel();
Use the following code for Xaml file:
<Window x:Class="DataContext_Test_Project.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:DataContext_Test_Project"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800"
x:Name="Window" DataContext="{DynamicResource ViewModel}">
<Window.Resources>
<local:ViewModel x:Key="ViewModel"/>
</Window.Resources>
<Grid>
<ListBox
HorizontalAlignment="Left"
Height="100"
Margin="334,132,0,0"
VerticalAlignment="Top"
Width="100"
ItemsSource="{Binding Path=SampleLines}"/>
<TextBox
HorizontalAlignment="Left"
Height="23"
Margin="184,166,0,0"
TextWrapping="Wrap"
VerticalAlignment="Top"
Width="120"
Text="{Binding Path=OneLineOnly}"/>
</Grid>
</Window>
I am relatively new to MVVM in WPF and have been trying to solve an issue for several days now. I am using the dragablz tab control and binding the ItemsSource which is an ObservableList of objects. The content of the Tab Item is a UserControl, however; its datacontext is null. I've created a simple setup to demonstrate the issue I'm having:
Model/ViewModel Classes:
public class Item
{
public string Header { get; set; }
public ItemContent Body { get; set; }
}
public class ItemContent
{
public string Name { get; set; }
public string Description { get; set; }
}
class MainWindowViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged([CallerMemberName]string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public ObservableCollection<Item> Items { get; set; }
}
Main Window XAML
<Window x:Class="WpfTestApplication.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:WpfTestApplication"
xmlns:views="clr-namespace:WpfTestApplication.ViewModels"
xmlns:dragablz="clr-namespace:Dragablz;assembly=Dragablz"
xmlns:dockablz="clr-namespace:Dragablz.Dockablz;assembly=Dragablz"
mc:Ignorable="d"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<views:MainWindowViewModel />
</Window.DataContext>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition />
</Grid.RowDefinitions>
<Button Name="btnAdd" Content="Add" Click="btnAdd_Click" />
<dockablz:Layout Grid.Row="1">
<dragablz:TabablzControl HeaderMemberPath="Header" ItemsSource="{Binding Items}" SelectedIndex="1">
<dragablz:TabablzControl.ContentTemplate>
<DataTemplate DataType="{x:Type views:Item}">
<local:TabItemControl />
</DataTemplate>
</dragablz:TabablzControl.ContentTemplate>
</dragablz:TabablzControl>
</dockablz:Layout>
</Grid>
</Window>
Tab Item XAML
<UserControl x:Class="WpfTestApplication.TabItemControl"
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:WpfTestApplication"
xmlns:views="clr-namespace:WpfTestApplication.ViewModels"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<UserControl.DataContext>
<views:ItemContent />
</UserControl.DataContext>
<Grid>
<TextBox Text="{Binding Body}" />
</Grid>
</UserControl>
And the btnAdd_Click event
Note that I don't use this in my actual code but it was a fast and dirty way to add tab items dynamically without adding a command.
private void btnAdd_Click(object sender, RoutedEventArgs e)
{
((ViewModels.MainWindowViewModel)DataContext).Items.Add(new ViewModels.Item() { Header = "New One", Body = new ViewModels.ItemContent() { Name = "This One" } });
}
Will answered my question in the comment to the original question. I used his answer to another post: https://stackoverflow.com/a/44729258/1228 to do the following.
I removed this from my UserControl:
<UserControl.DataContext>
<views:ItemContent />
</UserControl.DataContext>
I then added a dependency property called Body to my UserControl code behind:
public static readonly DependencyProperty BodyProperty =
DependencyProperty.Register("Body",
typeof(ViewModels.ItemContent),
typeof(TabItemControl),
new PropertyMetadata(null));
public ViewModels.ItemContent Body
{
get
{
return (ViewModels.ItemContent)GetValue(BodyProperty);
}
set
{
SetValue(BodyProperty, value);
}
}
public string BodyText {
get
{
return Body?.Name;
}
set
{
if (Body != null)
{
Body.Name = value;
}
}
}
I updated my MainWindow's Tab control ContentTemplate as such:
<dragablz:TabablzControl.ContentTemplate>
<DataTemplate DataType="{x:Type views:ItemContent}">
<local:TabItemControl Body="{Binding Body}" />
</DataTemplate>
</dragablz:TabablzControl.ContentTemplate>
And changed my UserControl to use the BodyText property for the value of the TextBox:
<Grid x:Name="LayoutRoot">
<TextBox Text="{Binding BodyText}" />
</Grid>
This is out of curiousity question. I know you should not structure any real WPF applications this way.
Working within and using only the MainWindow Class how do you bind an XAML element to a CLR property?
Here is my XAML.
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<TextBlock DockPanel.Dock ="Top" Height="50" Width="50"
Background ="AliceBlue" FontSize ="16" />
</Grid>
</Window>
And Code
namespace WpfApplication1
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window, INotifyPropertyChanged
{
string _myString = "hello world";
public string MyString
{
get { return _myString; }
}
public MainWindow()
{
InitializeComponent();
}
public event PropertyChangedEventHandler PropertyChanged;
void OnPropertyChanged(string propName)
{
if (this.PropertyChanged != null)
this.PropertyChanged(
this, new PropertyChangedEventArgs(propName));
}
}
}
So I want to display the string in the textblock. I think its a simple binding but I can't find the right syntax. Thanks
You must set your window data context to itself.
<Window.DataContext>
<Binding RelativeSource="{RelativeSource Self}"/>
</Window.DataContext>
then you cant bind to your property MyString
<TextBlock DockPanel.Dock ="Top" Height="50" Width="50"
Background ="AliceBlue" FontSize ="16" />
In this case you can simply do:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525"
x:Name="MainWindow">
<Grid>
<TextBlock DockPanel.Dock ="Top" Height="50" Width="50"
Background ="AliceBlue" FontSize ="16"
Text="{Binding MyString, ElementName=MainWindow}" />
</Grid>
</Window>