Question

I am writing a Windows 8 Store App (Metro / Modern?) and I am creating a control to re-use the formatting on multiple forms. I have created some WPF apps in the past and I attempted to create a Dependency Property the same way that I did in WPF. When I put the control on a form to use it though, I can’t get any value returned.

My personControl.cs WPF class:
public partial class PersonControl : UserControl
{

    public PersonControl()
    {
        InitializeComponent();

    }

    public static readonly DependencyProperty PersonProperty = 
        DependencyProperty.Register("thisPerson", typeof(Person), typeof(PersonControl));

    public Person thisPerson
    {
        get
        {
            return (Person)GetValue(PersonProperty);
        }
        set
        {
            SetValue(PersonProperty, value);
        }
    }

}

for the windows 8 app it requires PropertyMetadata to be added — I’m assuming that this is where I am going wrong, but I haven’t been able to track down what to do instead:

public partial class PersonControl : UserControl
{

    public PersonControl()
    {
        InitializeComponent();

    }

    public static readonly DependencyProperty PersonProperty = 
        DependencyProperty.Register("thisPerson", typeof(Person), typeof(PersonControl), new PropertyMetadata(new Person()));

    public Person thisPerson
    {
        get
        {
            return (Person)GetValue(PersonProperty);
        }
        set
        {
            SetValue(PersonProperty, value);
        }
    }

}

---

nothing has changed in the usage or binding of the control in the XAML that I know of. I am still using sample data so I create a List(Person) and then make a listbox and bind the listbox to the List(Person).

---

here is the binding code:

On the usercontrol xaml:

<Grid x:Name=”PersonGrid”>
…….
<TextBox x:Name="txtFirstName" Text="{Binding Path=thisPerson.FirstName, ElementName=This}"></TextBox>

On the mainpage Xaml:

<StackPanel x:Name="layoutRoot">        
   <ListBox x:Name="myListbox">
       <ListBox.ItemTemplate>
           <DataTemplate>
                <local:PersonControl x:Name="myControl" thisPerson="{Binding Path=.}" Margin="5"></local:PersonControl>               
           </DataTemplate>
       </ListBox.ItemTemplate>
   </ListBox>

Main page code behind:

List<Person> People = new List<Person>();
… populate data … 
myListbox.ItemsSource = People;

---

As an additional note — when I take the contents of the UserControlXaml and put the UI elements directly into the XAML on the main page, it works fine — it is when I use the UserControl that it fails.

Answer 1

It appears that the line in XAML on the usercontrol:

<TextBox x:Name="txtFirstName" Text="{Binding Path=thisPerson.FirstName, ElementName=This}">

doesn’t work the same in Windows 8 — when I took out the reference to the ElementName and the DependencyProperty (and just let .Net figure that out on it’s own I guess?) it worked fine.

so:

 <TextBox x:Name="txtFirstName" Text="{Binding Path=FirstName}"></TextBox>

works fine and the Binding is functional now.