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MVVM Light - User Controls as Views

由 怎甘沉沦 提交于 2019-12-03 09:06:15
Stunna

So your approach is very plausible. There are certain intricacies you'll have to use in order to get that functionality. I had to use a "MainViewModel" which contained all the view models. These view models behave such that when the data context switched to a different view model, the corresponding user control would change to the appropriate view. A good example which I followed was answered by Sheridan here. Hook into your app.xaml with the appropriate data templates and data context switches will be handled like magic :D

Where I diverged from Sheridan's example (because I didn't want to create a separate relay command class/object), I actually used mvvm light (galasoft) to send messages from my viewmodels to message back to the "MainViewModel" to switch its data context. A good example of using MVVM light messaging can be found here. Send the message from the "child" View Model and register it in the "MainViewModel."

Good luck!

Can't you use an Interface for exemple IChildLayout ? Each ViewModel inherit of this interface...

public interface IChildLayout:INotifyPropertyChanged
{
    public MainWindows_ViewModel Parent;
}

In your MainWindows ViewModel you can have something like this...

A property IChildLayout, which changes when you click on your buttons...

public class MainWindows_ViewModel:INotifyPropertyChanged
{
    public MainWindows_ViewModel()
    {
        //Here i set the default ViewModel
        this.Child=new First_ViewModel(){Parent=this};
    }

    private IChildLayout _child;
    public IChildLayout Child
    {
        get
        {
            return _child;
        }
        set
        {
            _child=value;
            _child.Parent=this;
            NotifyPropertyChanged("Child");
        }
    }
    #region INotifyPropertyChangedMembers...
}

For each layout you can retrieve the parent window ViewModel (it is important to switch the layout by editing the "Child" property from it's own ViewModel...)

You put a UserControl inside of your mainwindows (in the xaml), the content is Binded to your Child property then it will be refresh each time you change your Child property.

<Windows>
    <Windows.DataContext>
        <local:MainWindows_ViewModel/>
    </Windows.DataContext>
    <UserControl Content={Binding Child}>
        <UserControl.Resources>
            <DataTemplate DataType="{x:Type ViewModels:First_ViewModel}">
                    <Controls:First_View DataContext="{Binding}"/>
            </DataTemplate>
            <DataTemplate DataType="{x:Type ViewModels:Second_ViewModel}">
                    <Controls:Second_View DataContext="{Binding}" />
            </DataTemplate>
         </UserControl.Resources>
    </UserControl>
</Windows>

In this case, your First_ViewModel can be : (In this sample, I use prism DelegateCommand to bind button actions...

public class First_ViewModel:IChildLayout
{
public MainWindows_ViewModel Parent {get;set;}

public ICommand cmdBtn1click{get;set;}
private Pass_to_second_ViewModel()
{
    //Here i change the Parent Child Property, it will switch to Second_View.xaml...
    this.Parent.Child=new Second_ViewModel();
}

public First_ViewModel()
{
    // Here i connect the button to the command with Prism...
    this.cmdBtn1click=new DelegateCommand(()=>Pass_to_second_ViewModel());

}

#region INotifyPropertyChangedMembers...

}

I hope this will help you, i did this sort of thing to manage different Tab in a WPF application.

标签
c#
xaml
mvvm
user-controls
mvvm-light
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