CODEWITHSUNDEEP
c#wpfmvvmuwp
Mr. Developer
Mr. Developer

Reputation: 3417

Binding Page with ViewModel (MVVM) on Universal Windows App

I need to bind a page on Frame control in Xaml wpf page. my xaml page: 

<Page
x:Class="MyPro.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:MyPro"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:viewmodel="using:MyPro.ViewModel"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:x1="using:System"
mc:Ignorable="d">
<Page.DataContext>
    <viewmodel:PagerViewModel x:Name="PagerViewModel"></viewmodel:PagerViewModel>
</Page.DataContext>
<Frame 
       VerticalContentAlignment="Stretch"
       HorizontalContentAlignment="Stretch"
       Name="frameMainPage"
       DataContext="{Binding Source=Pager.Page, Mode=TwoWay}">        
</Frame>

I've tried to use this (but i don't know if it's correct):

DataContext="{Binding Source=Pager.Page, Mode=TwoWay}"

but doesn't work.

My view model, i call Pager to set the new Page: 

class PagerViewModel
{
    public PagerViewModel()
    {
        m_pager = new Pager();
    }

    public static Pager m_pager;  
    public Pager Pager
    {
        get
        {
            return m_pager;
        }
        set
        {
            m_pager = value;
        }
    }
}

and my model, i set page mode like this: 

public class Pager : INotifyPropertyChanged
{
    private Page m_page;
    public Page Page
    {
        get
        {
            return m_page;
        }
        set
        {
            m_page = value;
            OnPropertyChanged("Page");
        }
    }

    #region INotifyPropertyChanged Members

    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    #endregion
}

I need to change page like this from every part in the code: 

PagerViewModel.m_pager.Page = new MyPage();

How can I do this on Universal windows app UWP?

Upvotes: 0

Views: 2354

Answers (2)

Mr. Developer
Mr. Developer

Reputation: 3417

I've solved like this: 

DataContext="{Binding Path=Pager.Page, Mode=TwoWay}"

You have to use Path and not Source in Universal App on UWP

Upvotes: 2

Martin Zikmund
Martin Zikmund

Reputation: 39102

Binding to DataContext of Frame does not do anything. DataContext is basically only telling the control what do its binding's relative paths refer to, but don't cause any behavior (or at least this holds for the built-in controls).

In your case you need to bind to the Content property of the Frame control:

<Frame Content="{Binding Pager.Page}" />

This does work for me, I have tested it on a blank solution with your code and an additional button on the main page:

XAML

<Page
    x:Class="App4.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:App4"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">
    <Page.DataContext>
        <local:PagerViewModel x:Name="PagerViewModel"></local:PagerViewModel>
    </Page.DataContext>
    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <Frame Width="500" Height="500" Content="{Binding Pager.Page}" />
        <Button Click="ButtonBase_OnClick">Click</Button>
    </Grid>
</Page>

Code-behind

public sealed partial class MainPage : Page
{
    public MainPage()
    {
        this.InitializeComponent();
    }

    private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
    {
        ((PagerViewModel)DataContext).Pager.Page = new SecondPage();
    }
}

SecondPage is an empty page which I set to have a blue background to be able to clearly see that it is displayed in the Frame.

Upvotes: 1

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