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How do I access XAML bound class properties in code? (C#, WPF form)

In the example below, I am using XAML to set the DataContext to a class name, not an object name (as far as I can tell). The binding works - the txtEcho textbox shows what is entered in the txtName textbox when the latter loses focus. I want to be able to access the properties of this class in code-behind so I need an object reference. I could create a Person object and set the DataContext to that but the pattern in the books I am consulting does not do that - the class name is used and an object is not explicitly created in the examples in these textbooks.
<Window x:Class="WpfApplication5.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication5"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<local:Person x:Key="personData" />
</Window.Resources>
<Grid>
<Grid.DataContext>
<Binding Source="{StaticResource personData}" />
</Grid.DataContext>
<TextBlock HorizontalAlignment="Left" Margin="27,41,0,0" TextWrapping="Wrap" Text="Name" VerticalAlignment="Top" Height="23"/>
<TextBox x:Name="txtName" Text="{Binding Name}" HorizontalAlignment="Left" Height="23" Margin="78,42,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
<TextBox x:Name="txtEcho" Text="{Binding Name}" HorizontalAlignment="Left" Height="23" Margin="262,42,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
</Grid>
</Window>
The code is
namespace WpfApplication5
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
//txtFreedom.Text = <what exactly?>.Name; // no object reference!
}
}
class Person : INotifyPropertyChanged
{
string name;
public string Name
{
get { return this.name; }
set
{
this.name = value;
OnPropertyChanged("Name");
}
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string propertyName)
{
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}

You could access the Person instance that you create in your XAML like this:
private void Button_Click(object sender, RoutedEventArgs e)
{
Person person = this.Resources["personData"] as Person;
txtFreedom.Text = person.Name;
}

I found a way, with mm8's help. The code is now
namespace WpfApplication5
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public static Person oPerson;
public MainWindow()
{
InitializeComponent();
oPerson = this.Resources["personData"] as Person;
}
private void Button_Click(object sender, RoutedEventArgs e)
{
txtFreedom.Text = oPerson.Name;
}
}
public class Person : INotifyPropertyChanged
{
string name;
public string Name
{
get { return this.name; }
set
{
this.name = value;
OnPropertyChanged("Name");
}
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string propertyName)
{
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
The differences are, Declare a public static variable to hold a Person object.
public static Person oPerson;
In the MainWindow() method set it to the behind-the-scenes Person instance.
oPerson = this.Resources["personData"] as Person;
I had to make the class public to stop a compiler accessibility objection.
public class Person : INotifyPropertyChanged
Now I can reference the properties of the instance.
private void Button_Click(object sender, RoutedEventArgs e)
{
txtFreedom.Text = oPerson.Name;
}

How to call a method in c# class with parameters set in WPF user control textbox

Having a main c# class CtrlMain with method testForm it opens a WPF form (testFormCtrl)that shows a textbox and assigns a variable Xmin with the value introduced on textbox.
I want to execute method wantToExe from opened wpf user control with value introduced on textbox as a parameter
Here is what I have:
public partial class CtrlMain : UserControl
{
int mCounter;
double firstPos;
double[] currentBounds;
//ETC..
//constructor and class methods
//this opens a user control
static void testForm()
{
GenericWindow goWin;
testFormCtrl mytestFormCtrl = new testFormCtrl();
goWin = new GenericWindow(App.Current.MainWindow, mytestFormCtrl);
goWin.Title = "test";
goWin.ShowDialog();
}
//how to call this method with parameter of textbox?
public double wantToExe(double externalX){
double result;
//DO SOME COMPUTING
return result;
}
}
the testFormCtrl xaml is:
<UserControl x:Class="testFormCtrl"
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:telerik="http://schemas.telerik.com/2008/xaml/presentation"
mc:Ignorable="d">
<Grid Height="300">
<Grid>
<GroupBox Header="Location" Height="93" HorizontalAlignment="Left" Margin="4,3,0,0" Name="GBoxGridDefinition" VerticalAlignment="Top" Width="624">
<Grid>
<TextBlock Height="20" HorizontalAlignment="Left" Margin="20,13,0,0" Name="TblockXmin" Text="Xmin:" VerticalAlignment="Top" Width="36" />
<TextBox Name="TextBoxXmin" Height="20" Width="89" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="59,9,0,0" Text="{Binding Path=Xmin, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True,NotifyOnValidationError=True}" >
</TextBox>
<telerik:RadButton Content="Execute X" IsEnabled="True" Height="22" HorizontalAlignment="Left" Margin="484,9,0,0" Name="ButtonExecuteX" VerticalAlignment="Top" Width="102" telerik:StyleManager.Theme="Vista" />
</Grid>
</GroupBox>
</Grid>
</Grid>
</UserControl>
and c# code is
public partial class testFormCtrl : UserControl
{
double gnXmin;
public event PropertyChangedEventHandler PropertyChanged;
public double Xmin
{
get { return gnXmin; }
set
{
gnXmin = value;
OnPropertyChanged("Xmin");
}
}
void OnPropertyChanged(string lcProperty)
{
if (this.PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(lcProperty));
}
}
public testFormCtrl ()
{
InitializeComponent();
}
private void ButtonExecuteX_Click(object sender, RoutedEventArgs e)
{
//how to call CtrlMain.wantToExe(Xmin) ???
}
}
}
How can I call that method from other class, I can not make it static....

Just create a new constructor for your testFormCtrl class that accepts CtrlMain as a parameter:
private CtrlMain _caller;
public testFormCtrl(CtrlMain caller)
: this()
{
_caller = caller;
}
Then you can just invoke its methods:
private void ButtonExecuteX_Click(object sender, RoutedEventArgs e)
{
if(_caller != null) caller.wantToExe(Xmin);
}
Remember to pass the instance of CtrlMain in your testForm method:
static void testForm()
{
GenericWindow goWin;
testFormCtrl mytestFormCtrl = new testFormCtrl(this); //use the new constructor
goWin = new GenericWindow(App.Current.MainWindow, mytestFormCtrl);
goWin.Title = "test";
goWin.ShowDialog();
}

Trying to understand how i can bind a WPF DP in a different class

I am trying WPF to develop a tiny scoreboard.
In this project i have 3 XAML files.
ControlDisplay.xaml : Here is where i set the points for team 1 and team 2 in the scoreboard. Right now i only have 1 textbox for the scoreboard title.
Layout1.xaml : First layout, contains only a title for now.
Layout2.xaml : Second layout, same as above, only contains a title.
My idea is as following. I update one singleton class that has one property Title. Both Layout1 and Layout2's label for the title will bind to this singleton class property Title.
I created the basic structure for it.
ControlDisplay.xaml:
public partial class ControlDisplay : Window
{
private IScoreboardData _scoreboardData;
private Layout1 _layout1;
private Layout2 _layout2;
public ControlDisplay()
{
InitializeComponent();
_scoreboardData = SimpleInjectorContainer.Container.GetInstance<IScoreboardData>();
}
private void ShowLayout1(object sender, RoutedEventArgs e)
{
_scoreboardData.Title = "Test";
_layout1 = new Layout1();
_layout1.Show();
}
private void ShowLayout2(object sender, RoutedEventArgs e)
{
_scoreboardData.Title = "Test";
_layout2 = new Layout2();
_layout2.Show();
}
}
Layout1.xaml.cs (layout2 is a copy of layout1 codewise, just a different class name)
public partial class Layout1 : Window
{
private IScoreboardData _scoreboardData;
public Layout1()
{
_scoreboardData = SimpleInjectorContainer.Container.GetInstance<IScoreboardData>();
InitializeComponent();
}
}
Layout1.xaml
<Window x:Class="SmallScoreboard.Layout1" .... x:Name="LayoutOne">
<StackPanel>
<Label DataContext="{Binding ElementName=LayoutOne}" Content="{Binding _scoreboardData.Title}" />
</StackPanel>
</Window>
ScoreboardData.cs
public ScoreboardData : IScoreboardData
{
public string Title { get; set; }
}
This obviously does not work since i don't register a dependency property anywhere? How can i register a dependency property inside the ScoreboardData class? or is there a better way to solve this?
I want to be able to add more layouts in the future and i hope that i don't have to add the base binding logic to each and everyone of those layout(x).xaml.cs files.
Update
This is my Layout1.xaml file right now:
<Window x:Class="Simple_Scoreboard.Layout1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Layout" Height="500" Width="800"
ScrollViewer.VerticalScrollBarVisibility="Hidden" ScrollViewer.HorizontalScrollBarVisibility="Hidden"
WindowStyle="None"
AllowsTransparency="True"
ResizeMode="CanResizeWithGrip"
x:Name="LayoutOne" MouseLeftButtonDown="DWindow_MouseLeftButtonDown">
<StackPanel>
<Label Content="{Binding Path=Title, Mode=OneTime}" FontSize="30" HorizontalAlignment="Center" HorizontalContentAlignment="Center" VerticalAlignment="Center" VerticalContentAlignment="Center" Margin="0,10,0,0" FontWeight="Bold"></Label>
<Button Content="Button" Click="Button_Click_1"/>
</StackPanel>
</Window>
and the Layout1.xaml.cs
public partial class Layout1 : Window
{
public IScoreboardData _scoreboardData;
public Layout1()
{
InitializeComponent();
_scoreboardData = ScoreboardContainer.Container.GetInstance<IScoreboardData>();
DataContext = _scoreboardData;
}
private void DWindow_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
DragMove();
}
private void Button_Click_1(object sender, RoutedEventArgs e)
{
_scoreboardData.Title = "Click change title";
}
}
and finally the ScoreboardData class:
class ScoreboardData : IScoreboardData, INotifyPropertyChanged
{
private string _title;
public string Title
{
get { return _title; }
set
{
_title = value;
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs("Title"));
}
}
#region INotifyPropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
#endregion
}

I think your problem is in binding to a private field _scoreboardData;
you should make it a public property. But much better solution would be to bind to a window DataContext.
in the window constructor
public Layout1()
{
_scoreboardData = SimpleInjectorContainer.Container.GetInstance<IScoreboardData>();
InitializeComponent();
DataContext = _scoreboardData;
}
In the XAML
<Window x:Class="SmallScoreboard.Layout1" .... x:Name="LayoutOne">
<StackPanel>
<Label Text="{Binding Title}" />
</StackPanel>
</Window>
This way you have your scoreBoardData as Window DataContext and all bindings without explicitly specified source will bind to that object.
UPDATE:
ScoreboardData should implement INotifyPropertyChanged..
public class ScoreboardData :IScoreboardData, System.ComponentModel.INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private string _title;
public string Title
{
get { return _title; }
set
{
_title = value;
if(PropertyChanged!=null)
PropertyChanged(this,new PropertyChangedEventArgs("Title"));
}
}
}

Unable to add a new row to the observablecollection listbox?

In my project I have the following pages:
Mainwindow.xaml
Window1.xaml
User.cs
App.xaml
I declared the Name and Age property in User.cs and on MainWindow.xaml I made a ObservableCollection for a ListBox. MainWindow has a Button Add. When we click on the Add button. Then the Window1.xaml form is displayed. Which has two TextBoxes of name and age and a button (ADD Name). Now I want when we click on the Add Name button then the details in the both text boxes are attached to the ObservableCollection that is defined on the Mainwindow.xaml.cs.
Please suggest me want can I do:
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
}
private void OnInit(object sender, RoutedEventArgs e)
{
string textA=textBox1.Text;
int textB=Convert.ToInt32(textBox2.Text);
this.DataContext = new User(textA, textB);
}
private void button1_Click(object sender, RoutedEventArgs e)
{
User user = (User)(this.DataContext);
new MainWindow().observableCollection.Add(user);
this.Close();
}
}
now I ran this code I am unable to get the values in the user object.

The problem is you are not accessing the MainWindow CbservableCollection, you are creating a new MainWindow.
If this Window1 is a dialog you have a few options
Pass the MainWindow into Window1 as its owner
Use the Window1 as a dialog and fetch the changes when it closes
personally I think the 2nd option is the best, but it depends how you are calling Window1
Example2:
MainWindow Class
public partial class MainWindow : Window
{
private ObservableCollection<User> _myList = new ObservableCollection<User>();
public MainWindow()
{
InitializeComponent();
}
public ObservableCollection<User> MyCollection
{
get { return _myList; }
set { _myList = value; }
}
private void button1_Click_1(object sender, RoutedEventArgs e)
{
var dialog = new Window1();
if (dialog.ShowDialog() == true)
{
MyCollection.Add(dialog.NewUser);
}
}
}
MainWindow xaml
<Window x:Class="WpfApplication8.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="233" Width="405" Name="UI">
<Grid DataContext="{Binding ElementName=UI}" >
<ListBox ItemsSource="{Binding MyCollection}" DisplayMemberPath="TextA" Margin="0,0,0,47" />
<Button Content="Add" Height="23" HorizontalAlignment="Left" Margin="0,0,0,12" Name="button1" VerticalAlignment="Bottom" Width="75" Click="button1_Click_1" />
</Grid>
</Window>
Window1 xaml
<Window x:Class="WpfApplication8.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="119" Width="300" Name="UI">
<StackPanel DataContext="{Binding ElementName=UI}">
<TextBox Text="{Binding NewUser.TextA}" />
<TextBox Text="{Binding NewUser.TextB}" />
<Button Click="button1_Click" HorizontalAlignment="Right" Width="90" Height="30" Content="Add" />
</StackPanel>
</Window>
Window1 code
public partial class Window1 : Window, INotifyPropertyChanged
{
private User _newUser = new User();
public Window1()
{
InitializeComponent();
}
public User NewUser
{
get { return _newUser; }
set { _newUser = value; NotifyPropertyChanged("NewUser"); }
}
private void button1_Click(object sender, RoutedEventArgs e)
{
DialogResult = true;
}
public event PropertyChangedEventHandler PropertyChanged;
public void NotifyPropertyChanged(string property)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(property));
}
}
}
User Class
public class User : INotifyPropertyChanged
{
private string _textA;
private string _textB;
public string TextA
{
get { return _textA; }
set { _textA = value; NotifyPropertyChanged("TextA"); }
}
public string TextB
{
get { return _textB; }
set { _textB = value; NotifyPropertyChanged("TextB"); }
}
public event PropertyChangedEventHandler PropertyChanged;
public void NotifyPropertyChanged(string property)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(property));
}
}
}

Data Binding between two TextBoxes in different windows

I have created a program that changes the name in a TextBox when check or unckeck a Checkbox. I want to replicate this Textbox in a different window. I thought with Data Mining in the xaml would be possible, but the name only appears in one window. Second window window does´t recieve the data. I show you the code of the two windows.
Can you help me? Thankss
Window 1.cs---
namespace WpfApplication1
{
public partial class Window1 : Window
{
Texto prueba = new Texto("Carlos");
public static string s;
public Window1()
{
InitializeComponent( );
// Fill initial person fields
this.textBox1.Text = prueba.Name;
}
private void checkBox1_Checked(object sender, RoutedEventArgs e)
{
prueba.Name="Carlos";
textBox1.DataContext = prueba;
textBox1.Text = prueba.Name;
}
private void checkBox1_UnChecked(object sender, RoutedEventArgs e)
{
prueba.Name = "Luis";
textBox1.DataContext = prueba;
textBox1.Text = prueba.Name;
}
}
public class Texto
{
string name;
public string Name
{
get { return this.name; }
set { this.name = value; }
}
public Texto( ) {}
public Texto(string name)
{
this.name = name;
}
}
}
window1 xaml-------
<Grid>
<CheckBox Content="CheckBox" Height="16" HorizontalAlignment="Left" Margin="62,118,0,0" Name="checkBox1" VerticalAlignment="Top" Checked="checkBox1_Checked" Unchecked="checkBox1_UnChecked" />
<TextBox Height="23" HorizontalAlignment="Left" Margin="44,140,0,0" Name="textBox1" VerticalAlignment="Top" Width="120" />
</Grid>
window2 cs-----
namespace WpfApplication1
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void button1_Click(object sender, RoutedEventArgs e)
{
Window1 nueva = new Window1();
nueva.Show();
}
}
}
window2 xaml--------
<Grid>
<Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="82,121,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" />
<TextBox DataContext="prueba" Text="{Binding Path=Name}" Height="23" HorizontalAlignment="Left" Margin="57,84,0,0" Name="textBox2" VerticalAlignment="Top" Width="120" />
</Grid>

You will have to pass a reference to either the first window or the object that you're updating the text property on to the second window, it's DataContext property will do for that, you can then bind the second windows controls to it.
In this demo application I've created a MainWindow and a second window (Window1), the application starts in Main window like this.
MainWindow.xaml.cs
public partial class MainWindow : Window
{
public string TestString
{
get { return (string)GetValue(TestStringProperty); }
set { SetValue(TestStringProperty, value); }
}
public static readonly DependencyProperty TestStringProperty = DependencyProperty.Register("TestString", typeof(string), typeof(MainWindow), new UIPropertyMetadata(null));
public MainWindow()
{
InitializeComponent();
// setup the test string.
TestString = "this is a test.";
// Create the second window and pass this window as it's data context.
Window1 newWindow = new Window1()
{
DataContext = this
};
newWindow.Show();
}
}
MainWindow.xaml - Take note of the DataContext line in the Window declaration.
<Window x:Class="WpfApplication5.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"
DataContext="{Binding RelativeSource={RelativeSource Self}}"
>
<Grid>
<TextBox Text="{Binding TestString, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Margin="91,84,185,189" />
</Grid>
</Window>
Now for Window1 the code behind is just an empty default window class so I won't post it but the xaml is.
Window1.xaml
<Window x:Class="WpfApplication5.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<Grid>
<TextBlock Text="{Binding TestString, UpdateSourceTrigger=PropertyChanged}"/>
</Grid>
</Window>

Don't set the DataContext explicitly, or only via another Binding. Your
<TextBox DataContext="prueba"
does nothing helpful. DataContext will be inherited as long as it is not overwritten. Don't set it explicitly. It should be enought to set it once on both windows.
Create your data object in your MainWindow
Texto prueba = new Texto("Carlos");
Window1 nueva = new Window1();
nueva.DataContext = prueba;
nueva.Show();
and remove all the other DataContext assignments.

A couple of things wrong here, but I can probably give you a quick solution to fix your problem. First off your DataContext on window 2 isn't working properly, you can set it exclusively in your code right before you show window1...
private void button1_Click(object sender, RoutedEventArgs e)
{
Window1 nueva = new Window1();
this.DataContext = nueva.prueba;
nueva.Show();
}
Next you have to fire INotifyPropertyChanged in your Texto class...
public class Texto : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
string name;
public string Name
{
get { return this.name; }
set
{
this.name = value;
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs("Name"));
}
}
public Texto( ) {}
public Texto(string name)
{
this.name = name;
}
}

If both textboxes share a common datacontext it will "just work" without any code required...