Two way binding for TextBox

Question

This question was asked here for thousands times. But really, none of your examples and answers works for me. So let me show you my code.

public class PlayList : INotifyPropertyChanged{ public event PropertyChangedEventHandler PropertyChanged; public void OnPropertyChanged(string name) { var handler = PropertyChanged; if (handler != null) { PropertyChanged(this, new PropertyChangedEventArgs(name)); } } private string _dl; public string DriveLetter { get { return _dl; } set { if (value != _dl) { _dl = value; OnPropertyChanged("DriveLetter"); } } } } public partial class MainWindow : Window { public PlayList playlist = new PlayList(); private void Window_Loaded(object sender, RoutedEventArgs e) { Binding bind = new Binding("DriveLetter"); bind.Source = this.playlist; bind.Mode = BindingMode.TwoWay; bind.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged; textBox1.SetBinding(TextBlock.TextProperty, bind); this.playlist.DriveLetter = "A"; } }

Ofcourse WPF ignores this binding (nothing changes when I type in textbox, and nothing changes when I change playlist.DriveLetter property.

Debugger says, that PropertyChanged handler is not null

{Method = {Void OnPropertyChanged(System.Object, System.ComponentModel.PropertyChangedEventArgs)}}

So, any ideas what I am doing wrong. (I do not belive that WPF is wrong)?

Thanks in advance!

Is there any reason why you are building the binding in code instead of XAML? And have you tried using tools like Snoop for debugging the bindings, or have you tried setting breakpoints in your property to see if any code execution is taking place there? — Samuel Slade
– Samuel Slade, Commented Dec 7, 2011 at 12:49
Yes, there is quite good reason. I want to use playlist object later in code. — mszubart
– mszubart, Commented Dec 7, 2011 at 12:51
You can declare your Playlist object in code while setting it as the DataContext of the TextBox, or simply provide a property for it that the XAML can refer to for it's source. — Samuel Slade
– Samuel Slade, Commented Dec 7, 2011 at 14:54

RRUZ · Accepted Answer · 2011-12-07 13:31:53Z

6

Change

textBox1.SetBinding(TextBlock.TextProperty, bind);

to

textBox1.SetBinding(TextBox.TextProperty, bind);

edited Dec 7, 2011 at 13:31

RRUZ

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answered Dec 7, 2011 at 12:54

Rayden

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Comments

bolia · Accepted Answer · 2011-12-07 13:07:43Z

you don't have to do it this way, even if you want to use your playlist later on. Just use a Property in your Window like:

public PlayList PlayList { get; private set; }

and Bind your TextBox like this:

<TextBox Text="{Binding Path=PlayList.DriveLetter}"/>

you also have to set the DataContext of the Window, I think:

DataContext = this;

or you set the Data Context to your PlayList:

DataContext = PlayList;

so the Binding looks like this:

<TextBox Text="{Binding Path=DriveLetter}"/>

Haris Hasan · Accepted Answer · 2011-12-07 12:54:36Z

2

change

 textBox1.SetBinding(TextBlock.TextProperty, bind);

to

 textBox1.SetBinding(TextBox.TextProperty, bind);

You are binding TextBlock's text property rather than TexBox's text property

answered Dec 7, 2011 at 12:54

Haris Hasan

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1 Comment

mszubart Over a year ago

I am really sorry. Really sorry for my blindness (too fast typing + InteliSense). I'm going to Castorama to buy some rope. 2 Days wasted.

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