Multiple Data Contexts in View

Question

I have tried a few times to find an answer in the posts but not found yet (at least in what I understand since fairly new to WPF).

I define a Data Context in the view constructor:

this.DataContext = viewModel;

I would like to use multiple data contexts in a single view if possible? I have heard multiple inconsistent answers to this from others. The goal is that I need access to properties in multiple view models. For example my view XAML is used in cases like that shown below:

<MultiBinding Converter="{StaticResource multiBooleanToVisibilityConverter}">
                <Binding Path="ResultControlsVisibileByDefault" UpdateSourceTrigger="PropertyChanged"/>
                <Binding Path="StarWidthValueList.Count" UpdateSourceTrigger="PropertyChanged"/>
            </MultiBinding>

It would be great if I could explicitly reference each property in the appropriate view model.

Note: there are multiple view models based on windows that were overlaid in the main window. They become active based on wizard-like selections made by the user.

Answer 1

The easiest solution I've found is to have one ViewModel which holds the other ViewModels as Properties. Then the View can access the properties he wants from all the different ViewModels...

To illustrate, you can have a VMContainer:

public class VMContainer
{
    public FirstViewModel   VM1 { get; set; }
    public SecondViewModel  VM2 { get; set; }
}

Now in your view set your DataContext to an instance of a VMContainer which you already set the specific VM properties in...

Then you can do something like this in XAML

<Textbox Text="{Binding VM1.SomePropertyInFirstViewModel}" />
<Textbox Text="{Binding VM2.SomePropertyInSecondViewModel}" />

It's worth noting that you don't have to create a brand new VMContainer class just for this. You can also just add a new property in an existing VM for that other VM (if it's possible/logical based on what your VM represents)