WPF Caliburn Micro: Exchanging UserControls in a Window dynamically using ContentControl - wpf

Question

This question is related to Add a usercontrol to caliburm micro dynamically.
I have read any other related threads before open this new thread, but I still don't understand and find no solution. Please accept my apology if some of you take this as duplicate.
I have a window (MainView) contains "main" Grid (aka LayoutRoot) with 2 columns.
On left column there are 2 buttons: "Display View 1" and "Display View 2".
If user click "Display View 1", the "Display1View" (is a UserControl contains TextBlock with Text "View 1") should be shown on the right column, replace the current one.
If user click "Display View 2", the "Display2View" (is a UserControl contains TextBlock with Text "View 2") should be shown on the right column, replace the current one.
My sample code contains following views and viewmodels:
MainView.xaml and MainViewModel.cs
Display1View.xaml and Display1ViewModel.cs
Display2View.xaml and Display2ViewModel.cs
In my sample code the ContentControl doesn't recognize the UserControl. What am I doing wrong? How to bind ContentControl correctly? Please feel free to modify my sample code. Thank you in advance
MainView.xaml
<Window x:Class="TestCaliMiContentControl.MainView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Main View"
Width="525"
Height="350">
<Grid x:Name="LayoutRoot" ShowGridLines="True">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="30*" />
<ColumnDefinition Width="100*" />
</Grid.ColumnDefinitions>
<StackPanel x:Name="LeftNavPanel" Grid.Column="0">
<Button x:Name="Display1" Content="Display View 1" />
<Button x:Name="Display2" Content="Display View 2" />
</StackPanel>
<ContentControl x:Name="MainGridContent" Grid.Column="1" />
</Grid>
</Window>
MainViewModel.cs
public class MainViewModel : PropertyChangedBase
{
private ContentControl _mainGridContent;
public ContentControl MainGridContent
{
get { return _mainGridContent; }
set
{
_mainGridContent = value;
NotifyOfPropertyChange(() => MainGridContent);
}
}
public void Display1()
{
//MainGridContent = new Display1ViewModel(); // cannot convert source type error
}
public void Display2()
{
// MainGridContent = new Display2ViewModel(); // cannot convert source type error
}
}
Display1View.xaml
<UserControl x:Class="TestCaliMiContentControl.Display1View"
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"
d:DesignHeight="300"
d:DesignWidth="300"
mc:Ignorable="d">
<Grid>
<TextBlock HorizontalAlignment="Center" FontSize="72"
Text="View 1"/>
</Grid>
</UserControl>
Display1ViewModel.cs
using System;
using System.Windows.Controls;
using Caliburn.Micro;
namespace TestCaliMiContentControl
{
public class Display1ViewModel : PropertyChangedBase {}
}

Answer 1

First, I would start by recommending you read the Caliburn.Micro documentation, specifically the part about Screens, Conductors, and Composition: http://caliburnmicro.com/documentation/composition
That being said, we can modify your code to get it working.
1) Since your MainViewModel is supposed to be conducting other items, it should descend from Conductor<T>. In this case, we will have it conduct the Caliburn Screen class.
public class MainViewModel : Conductor<Screen>
2) In MVVM, you view models should know nothing of your view. You should not see UI classes such as ContentControl. We could change your property to be of type Screen, but we actually don't need that property at all since we are using a conductor. So, remove the MainGridContent property and backing field.
3) Within your Display1 and Display2 methods, invoke Caliburn's conductor method ActivateItem to show the appropriate item.
public void Display1()
{
ActivateItem(new Display1ViewModel());
}
4) In your MainView.xaml you will need to bind your ContentControl to the conductor's active item property, which is, by convention, ActiveItem.
<ContentControl x:Name="ActiveItem" Grid.Column="1" />
5) Finally, since your conductor is conducting Screens, you need to make them screens. Screens are helpful because they have lifecycle and allow you to know when they are activated/deactivated. Do this for both Display1 and Display2.
public class Display1ViewModel : Screen {}
This should get you up and running.