someone someone - 2 months ago 9
C# Question

Is it possible to access the DataContext of the current page of the frame? How?

In wpf, is it possible to access the DataContext of the current page of the frame? If YES, how?

If NO, what should I use as replacement for frame so that I can access its DataContext?

If something is not clear, please tell me.

Update: For Clarification

I have a

Frame
in
MainWindow.xaml
. I want to access the
DataContext
of the current page displayed in the
Frame
. Let's just say I want to display a
string
property named title of the
ViewModel
of the current page. (Let's assume that each page'
ViewModel
has title property)

Update: Here is my MainWindow.xaml

<Window x:Class="Libertalia.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
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"
.
.
.
DataContext="{Binding Main, Source={StaticResource Locator}}"
>
<ScrollViewer VerticalScrollBarVisibility="Auto">
<Grid>
<Frame Panel.ZIndex="1" x:Name="MainFrame" JournalOwnership="OwnsJournal" NavigationUIVisibility="Hidden" Source="View/BlankPage.xaml" />
</Grid>
</ScrollViewer>
</Window>


Code of the page (just one of it, just a sample):

<Page x:Class="Libertalia.View.LoginView"
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:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
xmlns:behaviors="clr-namespace:Libertalia.Behavior"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
.
.
.
DataContext="{Binding Page1, Source={StaticResource Locator}}"
<DockPanel Margin="200" >

</DockPanel>
</Page>


UPDATE: Model, View and ViewModel Relationship


  • MainWindow.xaml
    (View) is binded to
    MainViewModel.cs
    (ViewModel). In short,
    MainWindow.xaml's
    DataContext
    is
    MainViewModel.cs

  • MainWindow.xaml
    (View) has
    Frame

  • Frame
    has
    Page
    (View).
    Frame
    has many Pages, displayed one at a time.

  • Page
    has its own ViewModel (
    DataContext
    )



What I want to do:


  • Access current page' (of the Frame)
    DataContext
    from the
    DataContext
    of the MainWindow (MainViewModel).


Answer

I'm not sure that it will work for you, because I still don't understand the relationship between view models and models in your architecure, but try to use this idea:

1). My Window1's xaml has following content :

<Grid>       
    <Frame Panel.ZIndex="1"
           x:Name="MainFrame"
           JournalOwnership="OwnsJournal"
           NavigationUIVisibility="Hidden"
           Source="UserControl1.xaml" />
</Grid>

2) UserControl1 has definition of DataContext:

 public UserControl1()
    {
        InitializeComponent();
        DataContext = new MainViewModel();
    }

3). The code where I extract and modfy the DataContext of the Content of my Frame:

   Window1 window = new Window1();
        //window.Content = uc;


        var aa = window.Content as Grid;

        foreach (var e in aa.Children)
        {
            if (e is Frame)
            {
                Frame f = e as Frame;
                f.ContentRendered += F_ContentRendered;
            }
        }

//only inside of handler of ContentRendered event you can access to the content of your Frame:
  private void F_ContentRendered(object sender, EventArgs e)
    {
        var frame = sender as Frame;
        UserControl1 uc1 = frame.Content as UserControl1;
        MainViewModel mvm = uc1.DataContext as MainViewModel;

    }

It should work.