CODEWITHSUNDEEP
c#wpfdata-binding
D-Mac
D-Mac

Reputation: 92

Why isn't my WPF binding working?

This seems so easy. I've been doing some much more completed data binding, and now I can't get this simple test to work. What am I doing wrong?

Disclaimer: It is late on Friday after a long week.

Here is my XAML file:

<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="MainWindowControl"
        xmlns:diag="clr-namespace:System.Diagnostics;assembly=WindowsBase">
    <Grid>
        <TextBlock DataContext="{Binding ElementName=MainWindowControl, Path=Test, diag:PresentationTraceSources.TraceLevel=High}" />
    </Grid>
</Window>

And the code-behind:

using System.Windows;

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private string _test = "testing 1..2..3";
        public string Test { get { return _test; } set { _test = value; } }

        public MainWindow()
        {
            InitializeComponent();
        }
    }
}

And finally the debug output that shows it is working fine. But it doesn't!

System.Windows.Data Warning: 56 : Created BindingExpression (hash=24898218) for Binding (hash=15584387)
System.Windows.Data Warning: 58 :   Path: 'Test'
System.Windows.Data Warning: 60 : BindingExpression (hash=24898218): Default mode resolved to OneWay
System.Windows.Data Warning: 61 : BindingExpression (hash=24898218): Default update trigger resolved to PropertyChanged
System.Windows.Data Warning: 62 : BindingExpression (hash=24898218): Attach to System.Windows.Controls.TextBlock.DataContext (hash=61116530)
System.Windows.Data Warning: 67 : BindingExpression (hash=24898218): Resolving source 
System.Windows.Data Warning: 70 : BindingExpression (hash=24898218): Found data context element: <null> (OK)
System.Windows.Data Warning: 74 :     Lookup name MainWindowControl:  queried TextBlock (hash=61116530)
System.Windows.Data Warning: 78 : BindingExpression (hash=24898218): Activate with root item MainWindow (hash=22749765)
System.Windows.Data Warning: 108 : BindingExpression (hash=24898218):   At level 0 - for MainWindow.Test found accessor RuntimePropertyInfo(Test)
System.Windows.Data Warning: 104 : BindingExpression (hash=24898218): Replace item at level 0 with MainWindow (hash=22749765), using accessor RuntimePropertyInfo(Test)
System.Windows.Data Warning: 101 : BindingExpression (hash=24898218): GetValue at level 0 from MainWindow (hash=22749765) using RuntimePropertyInfo(Test): 'testing 1..2..3'
System.Windows.Data Warning: 80 : BindingExpression (hash=24898218): TransferValue - got raw value 'testing 1..2..3'
System.Windows.Data Warning: 89 : BindingExpression (hash=24898218): TransferValue - using final value 'testing 1..2..3'

Upvotes: 1

Views: 658

Answers (2)

icalderond
icalderond

Reputation: 19

You should set the datacontext into codebehind.

using System.Windows;
namespace WpfApplication1
 {
    /// <summary>    
    /// Interaction logic for MainWindow.xaml    
    /// </summary>

    public partial class MainWindow : Window
    {
        private string _test = "testing 1..2..3";    
        public string Test { get { return _test; } set { _test = value; } }

        public MainWindow()
        {
            InitializeComponent();
            this.Loaded+=(s,a)=>
             {
                this.DataContext=Test;
             };
        }
    }
}

Upvotes: 0

nvoigt
nvoigt

Reputation: 77364

You bound your string property to the DataContext of your TextBlock. It's working as it should. I can only guess, but did you mean to bind to the Text property of TextBlock so you can see the text appear? 

<TextBlock Text="{Binding ElementName=MainWindowControl, Path=Test" />

Upvotes: 3

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