How to bind WPF TextBox to a propperty that is the member of application main window

Question

I have a private field

private static Double myValue;

in the application MainWindow class. And there (in the MainWindow class) I defined a property

public static Double MytValue
{
    get { return myValue; }
}

In the structure of the MainWindow class I have a TextBox. I'm in need of binding it to the MytValue property. In XAML I write:

<TextBox Name="tbxMyValue" Grid.Row="1" Grid.Column="2" TextAlignment="Center"
         Text="{Binding Path=MyValue}" Width="Auto" Margin="10,0,10,15" IsEnabled="True" />

But it has no effect. I see nothing in the TextBox while myValue variable has a value. Why? Please help me.

Is it "MyValue" or "MytValue"? – rossisdead Oct 11 '12 at 20:53 — rossisdead, Oct 11 '12 at 20:53
I bag your pardon - it's MyValue ofcourse. – user1688773 Nov 01 '12 at 09:57 — user1688773, Nov 01 '12 at 09:57

score 5 · Answer 1 · answered Oct 11 '12 at 20:47

5

I like to set the DataContext in the Window section

<Window x:Class="Gabe3a.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:Gabe3a"
        xmlns:scm="clr-namespace:System.ComponentModel;assembly=WindowsBase"
        xmlns:System="clr-namespace:System;assembly=mscorlib"
        DataContext="{Binding RelativeSource={RelativeSource self}}"
        Title="Gabriel Main Ver 3a01" Icon="faviconw.ico" Height="600" Width="800">

answered Oct 11 '12 at 20:47

paparazzo

44,497
23
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nice, i never seen this before. – Ewerton Oct 11 '12 at 20:51
1

@Ewerton but not nice enough for a +1 ? – paparazzo Oct 11 '12 at 21:02

score 4 · Answer 2 · answered Oct 11 '12 at 17:48

You need to set the DataContext behind the Window for that binding to work

There are two layers to an application with WPF: the UI layer and the data layer.

The Data layer for an application starts out as null, and you can set it using the DataContext property.

Whenever you do a basic binding in WPF, you are binding to the DataContext. So Text="{Binding Path=MyValue}" is actually saying "Get the MyValue property from the current DataContext".

You could simply set the DataContext in your code behind:

MyWindow.DataContext = this;

Or you can use a RelativeSource binding to tell WPF to get the MyValue property from somewhere else, such as telling it to get it from the closest Window it finds when navigating up the VisualTree:

Text="{Binding Path=MyValue, RelativeSource={
    RelativeSource AncestorType={x:Type Window}}}"

I actually have an article on my blog about the DataContext that I'd recommend reading if you're new to WPF and the DataContext: What is this "DataContext" you speak of?

Congratulations, nice answer! – Ewerton Oct 11 '12 at 20:52 — Ewerton, Oct 11 '12 at 20:52

score 0 · Answer 3 · answered Oct 11 '12 at 17:45

0

It's not how it works. Binding to static properties; {Binding Source={x:Static local:Application.MyValue}}

Note that your field needs to be property & public. If you want to go with your solution, you need to set DataContext as {RelativeSource Self}.

answered Oct 11 '12 at 17:45

Erti-Chris Eelmaa

25,338
6
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score 0 · Answer 4 · answered Oct 11 '12 at 17:47

0

In file MainWindow.xaml.cs in constructor add this line:

DataContext = this;

after InitializeComponent();

answered Oct 11 '12 at 17:47

kmatyaszek

19,016
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So if MyValue is programmatically dynamically changed the value in text box will be accordingly changed each time? – user1688773 Nov 01 '12 at 10:17

How to bind WPF TextBox to a propperty that is the member of application main window

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