CODEWITHSUNDEEP
c#wpfdata-bindingstatic
Richard
Richard

Reputation: 11

Textbox not updating when static object method to update property is called

First, let me state I am new to C# altogether. At the moment I am working on a program, and have been trying to get something that I thought would be rather simple to do. This is apparently not the case. I'll show here a very small example of what I have been trying to do. This is functionally identical, but without all the extra things that I have in the real project. We have 3 files here.

MainWindow.xaml

<Window.Resources>
    <CollectionViewSource x:Key="data1ViewSource" d:DesignSource="{d:DesignInstance {x:Type local:Data1}, CreateList=True}"/>
</Window.Resources>
<Grid>
    <Button x:Name="TestButton" Content="Button" HorizontalAlignment="Left" Margin="78,25,0,0" VerticalAlignment="Top" Width="75" Click="TestButton_Click"/>
    <TextBox x:Name="testStringTextBox" HorizontalAlignment="Left" Height="24" Margin="78,86,0,309" Grid.Row="0" Text="{Binding TestString}" VerticalAlignment="Center" Width="120"/>
    <TextBlock x:Name="testStringTextBlock" HorizontalAlignment="Left" Margin="78,143,0,0" TextWrapping="Wrap" Text="{Binding TestString}" VerticalAlignment="Top" Height="181" Width="245"/>
</Grid>

MainWindow.xaml.cs

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void TestButton_Click(object sender, RoutedEventArgs e)
    {
        Class1.TheButton();
    }

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        System.Windows.Data.CollectionViewSource data1ViewSource = ((System.Windows.Data.CollectionViewSource)(this.FindResource("data1ViewSource")));
        // Load data by setting the CollectionViewSource.Source property:
        // data1ViewSource.Source = [generic data source]
    }
}

Class1.cs

public static class Class1
{
    private static int Inc = 1;
    public static Data1 testData = new Data1("Starting test\n");

    public static void TheButton()
    {
        testData.TestString += "Test number " + Inc.ToString() + ".\n";
        Inc++;
    }
}

public class Data1 : INotifyPropertyChanged
{
    public Data1(string input)
    {
        TestString = input;
    }

    private string _testString;
    public event PropertyChangedEventHandler PropertyChanged;
    public string TestString
    {
        get { return _testString; }
        set { _testString = value; OnPropertyChanged("TestString"); }
    }

    protected void OnPropertyChanged(string name)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(name));
        }
    }
}

The program compiles as is, without error, and when I set a breakpoint, I can view the object Class1.testData, and I can see the proper value in Class1.testData.TestString and _testString.

I have spent several days searching for some sort of simple example of what I'm trying to do here, and I have yet been able to find any solution to get it actually working. I've come to the conclusion that I must be doing something wrong or just plain missing something, but I also cannot find anything to give me insight on what that is.

Upvotes: 0

Views: 51

Answers (1)

Magnetron
Magnetron

Reputation: 8573

Change the xaml to use x:Static and provide the Path:

<Canvas>
    <Button x:Name="TestButton" Content="Button" HorizontalAlignment="Left" Margin="78,25,0,0" VerticalAlignment="Top" Width="75" Click="TestButton_Click"/>
    <TextBox x:Name="testStringTextBox" 
             HorizontalAlignment="Left" 
             Height="24" 
             Margin="78,86,0,309"
             Text="{Binding Source={x:Static local:Class1.testData}, Path=TestString}" 
             VerticalAlignment="Center" 
             Width="120"/>
    <TextBlock x:Name="testStringTextBlock" 
               HorizontalAlignment="Left" 
               Margin="78,143,0,0" 
               TextWrapping="Wrap" 
               Text="{Binding Source={x:Static local:Class1.testData}, Path=TestString}" 
               VerticalAlignment="Top" 
               Height="181" 
               Width="245"/>
</Canvas>

Also note the if you enter a value in the textbox, the value will only be updated in your variable when the textbox loses focus.

Upvotes: 2

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