Converting normal property to dependency property - wpf

Question

I have a control that I am using for my new application. This control has a regular property as such.
Public Property Value() As String
Get
If AutoCompleteTextBox.SearchText Is Nothing Then
Return String.Empty
Else
Return AutoCompleteTextBox.SearchText.ToString.Trim
End If
End Get
Set(value As String)
AutoCompleteTextBox.SearchText = value
End Set
End Property
Edit:
So, after multiple tries, I am finally at this stage.
Public Shared ValueProperty As DependencyProperty = DependencyProperty.Register("Value", GetType(String), GetType(AutoCompleteBox))
Public Property Value() As String
Get
Return Me.GetValue(ValueProperty).ToString
End Get
Set(value As String)
Me.SetValue(ValueProperty, value)
End Set
End Property
Public Event PropertyChanged As PropertyChangedEventHandler _
Implements INotifyPropertyChanged.PropertyChanged
This is the dependency property. This property is still not binding. No errors are shown in output window for binding.
Text="{Binding RelativeSource={RelativeSource Self}, Path=Value, Mode=TwoWay}"
This is my binding method. I have no idea what else I can do. At least if there was an error, I could have figured out something. Without any error, I am just a headless chicken here.

Answer 1

Please refer to the following url for all the dependency fundamentals
http://www.wpftutorial.net/dependencyproperties.html
Basically, you can get a property changed event of dependency property by providing a FrameworkPropertyMetadata.
new FrameworkPropertyMetadata( [Default Value],
OnCurrentTimePropertyChanged);
And you can get back the target control (DependencyObject) at the event handler and implement your logic over there
private static void OnCurrentTimePropertyChanged(DependencyObject source,
DependencyPropertyChangedEventArgs e)
{
AutoCompleteTextBox control = source as AutoCompleteTextBox;
string time = (string)e.NewValue;
// Put some update logic here...
}

Answer 2

Declaring a dependency property in a control is a good thing.
You could make some binding in the xaml (sorry I don't have your XAML - I imagine).
Something like :
<TextBox x:Name="AutoCompleteTextBox"
Text="{Binding RelativeSource={RelativeSource=Self},Path=Value}"/>
Regards

Answer 3

TextBox has a property called Text. When you access Text property it will give you text entered in TextBox. Same is your case. Now why you want to convert it into a DP ? A DP would be useful if you want o bind this DP to some other control.
Extend this control itself. Make a new control and introduce this new DP.
While a DP is used where you want to bind this property to some control. This property then gets updated from control or control gets updated from this DP depending upon binding mode set.
How to do binding :
<TextBox x:Name="UserInput" />
<uc:MyAutoCompleteTextBox ValueDP="{Binding Text, ElementName=UserInput, Mode=OneWay}" />
MyAutoCompleteTextBox is new control which extends(inherits) from your old AutoComplete control.
If you want to apply some filtering logic or anything else, you can apply it in your DP itself like this :
Get
someVariable = TryCast(Me.GetValue(ValueProperty), String)
' apply somg logic to someVariable
' use your old Value property from here
Return someVariable
End Get
There are many WPF Binding tutorials on net.
I recommend :
http://blog.scottlogic.com/2012/04/05/everything-you-wanted-to-know-about-databinding-in-wpf-silverlight-and-wp7-part-one.html

Answer 4

Just change your code with following code and you should be good
your code
Public Shared ReadOnly ValueProperty As DependencyProperty = DependencyProperty.Register("Value", GetType(String), GetType(AutoCompleteBox))
Public Property Value() As String
Get
Return TryCast(Me.GetValue(ValueProperty), String)
End Get
Set(value As String)
Me.SetValue(ValueProperty, value)
End Set
End Property
New code
Public Shared ReadOnly ValueProperty As DependencyProperty = DependencyProperty.Register("Value", GetType(String), GetType(AutoCompleteBox))
Public Property Value() As String
Get
If AutoCompleteTextBox.SearchText Is Nothing Then
Return String.Empty
Else
Return AutoCompleteTextBox.SearchText.ToString.Trim
End If
End Get
Set(value As String)
AutoCompleteTextBox.SearchText = value
End Set
End Property
This DP will do what your Older property was doing. But just think about your requirement there can be a better way of writing the things.
Thanks