Databinding WPF

Question

Hi All!

I wanted to create a control with a TextBox and to bind TextBox.Text property with my own Dependency Property TextProp. (Some kind of experiment) However, the binding does not work! What I am doing wrong?

XAML:

    <UserControl x:Class="WpfApplication1.UserControl1"
                 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:WpfApplication1">
            <TextBox Text="{Binding TextProp}" x:Name="textb"/>
    </UserControl>

C#:

public partial class UserControl1 : UserControl
    {
        public UserControl1()
        {
            InitializeComponent();
            TextProp = "fwef";
        }

        public string TextProp
        {
            get { return ( string )GetValue(TextPropProperty); }
            set { SetValue(TextPropProperty, value); }
        }

        public static readonly DependencyProperty TextPropProperty =
            DependencyProperty.Register("TextProp",typeof( string ),typeof(UserControl1));
    }

Answer 1

It looks like you forgot to set DataContext, from where Binding could get actual property...

Try one of the following:

C#

public UserControl1()
{
   InitializeComponent();
   TextProp = "fwef";
   DataContext = this;
}

Or

<UserControl x:Class="WpfApplication1.UserControl1"
             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:WpfApplication1"
             DataContext="{Binding RelativeSource={RelativeSource Self}}">
            <TextBox Text="{Binding TextProp}" x:Name="textb"/>
    </UserControl>

Or 2

<UserControl x:Class="WpfApplication1.UserControl1"
             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:WpfApplication1">
        <TextBox DataContext="{Binding RelativeSource={RelativeSource FindAncestory, AncestorType={x:Type local:UserControl}}} Text="{Binding TextProp}" x:Name="textb"/>
</UserControl>

I wrote this from head, hope I didn't make any typo here.

Hope it helps,

Cheers.