Windows Phone 8中的UserControl绑定MVVM

Question

I have this a simple usercontrol with a textbox

XAML:

<UserControl x:Name="myTextBox" x:Class="Views.UserControls.myTextBox"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
FontFamily="{StaticResource PhoneFontFamilyNormal}"
FontSize="{StaticResource PhoneFontSizeNormal}"
Foreground="{StaticResource PhoneForegroundBrush}" d:DesignWidth="480" Height="92">

<StackPanel>
    <StackPanel Margin="25,0,0,0" Orientation="Horizontal">
        <TextBlock TextWrapping="Wrap" Text="Title" FontSize="16" HorizontalAlignment="Left"/>
    </StackPanel>
    <TextBox x:Name="textbox" TextWrapping="Wrap" Text="{Binding Text, Mode=TwoWay}" VerticalAlignment="Top"/>
</StackPanel>

Code behind:

public partial class LabeledTextBox : UserControl
{
    public LabeledTextBox()
    {
        InitializeComponent();
        DataContext = this;
    }

    public static readonly DependencyProperty TextProperty = DependencyProperty.Register("Text", typeof(String), typeof(LabeledTextBox), new PropertyMetadata(default(String)));


    public String Text
    {
        get { return (String)GetValue(TextProperty); }
        set { SetValue(TextProperty, value); }
    }
}

}

And a page :

<phone:PhoneApplicationPage
[...]
>

<phone:PhoneApplicationPage.DataContext>
    <viewmodel:myViewModel/>
</phone:PhoneApplicationPage.DataContext>

<StackPannel>
    <TextBlock Text="{Binding Text, ElementName=myusertextbox}"/>

    <usercontrols:myTextBox x:Name="myusertextbox" Text="{Binding myText, Mode=TwoWay}"/>
</StackPannel>

In my viewmodel :

private String mytext;
public String myText
{
   get { return myText; }
   set { NotifyPropertyChanged(ref myText, value); }
}

the textblock as the good value and I can get the text to do something like that : myusertextbox.Text

But I would like to set automatically myText with the value of the textbox in my usercontrol.

I try all day but it still not working...

What am I missing? Thanks in advance.

EDIT:

public abstract class ANotifyPropertyChanged : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    public void NotifyPropertyChanged(string nomPropriete)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(nomPropriete));
    }

    public bool NotifyPropertyChanged<T>(ref T variable, T valeur, [CallerMemberName] string nomPropriete = null)
    {
        if (object.Equals(variable, valeur))
            return false;

        variable = valeur;
        NotifyPropertyChanged(nomPropriete);
        return true;
    }
}

Answer 1

private String mytext;
public String myText
{
   get { return myText; }
   set { NotifyPropertyChanged(ref myText, value); }
}

What kind of framework do you use for implementing INotifyPropertyChanged interface? You are not even setting the value to your private field here. This looks quite strange to me. It doesn't seem like it's following the get - set - notify route.

It is suppose to be something like:

private String mytext;
public String myText
{
   get { return myText; }
   set 
 { 
   mytext = value;
   NotifyPropertyChanged("myText"); 
 }
}