bind the text box of user control through mainwindow text - wpf

Question

I am working on WPF project. I have created a user control name as "CanLogPaneView". this user control contains a Text box called "txt_CanLog".
I have bind this Text box as mentioned below:
<UserControl x:Class="CANCONTROL.CanLogPaneView"
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:CANCONTROL"
xmlns:ViewModels="clr-namespace:CANCONTROL.ViewModels;assembly=CANCONTROL.ViewModels"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<UserControl.Resources>
<DataTemplate x:Key="MainWindowViewModel" DataType="{x:Type ViewModels:MainWindowViewModel}">
</DataTemplate>
</UserControl.Resources>
<DockPanel>
**<TextBox x:Name="txt_CanLog" Text="{Binding Text, Source={StaticResource MainWindowViewModel}}" >**
</TextBox>
</DockPanel>
</UserControl>
So I have bind the text box with mainwindow property Text. My main window have a view model. there I defined the property Text as mentioned below:
public string text = string.Empty;
public string Text
{
get
{
return text;
}
set
{
text = text + value;
}
}
in Main window code: MainWindow.xaml.cs I am adding text like
this.ViewModel.Text = "\n\nAPPLICATION CONFIGURATION\r\n";
What I want is through mainwindow.xaml.cs code I want to print some data in CanLogPaneView.xaml's textBox

Answer 1

Your MainWindowViewModel should be binded to your Usercontrol's DataContext instead.
Also, implement INotifyPropertyChanged in your MainWindowViewModel and RaisePropertyChange at your "Text" setter
Something like the following
<Window x:Class="WpfTestProj.MainWindow"
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"
xmlns:local="clr-namespace:WpfTestProj"
Title="MainWindow" Height="350" Width="525"
d:DataContext="{d:DesignInstance Type=local:MainViewModel, IsDesignTimeCreatable=False}">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="auto" />
</Grid.RowDefinitions>
<TextBox Text="{Binding Text}" />
</Grid>
public class MainViewModel : ViewModelBase
{
private string _text;
public string Text
{
get { return _text; }
set
{
_text = value;
OnPropertyChanged();
}
}
}