Bind multiple views to multiple viewmodels

5
votes

I have a WPF window displaying different self-defined Views. So far I was able to use everything I learned about MVVM :)

Now I got to a new "problem": I have 10 entities of the same view in a bigger view. These ten view-entities contain a set of controls (textbox, combobox etc.) but are all consistent.

So how do I bind these Views to a ViewModel?

I thought about having 10 instances of the ViewModel in the "higher-level" ViewModel and give the views fix-defined the instances of the VM as datacontext.

My question is now --> Is there a easier (or more convienient) way to bind many (identical) views to their viewmodels?

Code-Example:

View Model:

private PanelViewModel _panelViewModel1 = new PanelViewModel();
public PanelViewModel PanelVM1
{
   get { return _panelViewModel1; }
}

View-Example:

<myControls:vwPanel HorizontalAlignment="Left" x:Name="vwPanel1" 
                    VerticalAlignment="Top" DataContext="{Binding Path=PanelVM1}"/>

What bothers me is that I would need this logic ten times for ten views?

UPDATE: To answer some questions: I want to show one view 10 times (in my example) I defined my own view by inheriting from UserControl. So my vwPanel inherits from UserControl. The 10 vwPanels are just placed inside a StackPanel inside a Grid.

It's not about displaying data, as you pointed out, there would be a listview or a datagrid a better place to start. It's a special case where I need this much input-controls :/

UPDATE2: What I hoped for was more like defining a List of ViewModels and Bind my 10 Views to one of this List. But this will not work will it? At least I wouldn't know how to refernce one "special" entitiy in the list out of XAML...

2
c#wpfuser-interfacemvvm
Are the ten views in the bigger view specially defined? In other words, is there any reason why you can't, say, create a List and bind that List to an IEnumerable of your ViewModels and have them displayed that way? – Tim
@Tim I need them in correct order to have in- and output in the correct order. Would this be possible without having them specially-defined? – basti

2 Answers

8
votes

Typically I use implicit DataTemplates for mapping Views to ViewModels. They can go in <Application.Resources>, <Window.Resources> or even in under specific elements only such as <TabControl.Resources>

<DataTemplate DataType="{x:Type local:PanelViewModel}">
    <myControls:vwPanel />
</DataTemplate>

This means that anytime WPF encounters an object in the VisualTree of type PanelViewModel, it will draw it using vwPanel

Objects typically get placed in the VisualTree through an ItemsSource property

<ItemsControl ItemsSource="{Binding CollectionOfAllPanels}" />

or by using a ContentControl

<ContentControl Content="{Binding PanelVM1}" />
1
votes

If I understand your question correctly, you have a collection of something that you what to represent visually. That is, you have several viewmodels that you want to define a single view for, but show X number of times. Your example shows you using a panel as your view for the "PanelViewModel"...what is the parent item's control for the vwPanel? Assuming you're using something like a ListBox, you can define a custom DataTemplate that contains your vwPanel and assign that DataTemplate to your ListBox.ItemTemplate.

For example:

<Window.Resources>
    <DataTemplate x:Key="myVMTemplate" TargetType="{x:Type myViewModels:PanelViewModel}">
        <myControls:vwPanel HorizontalAlignment="Left" VerticalAlignment="Top"/>
    </DataTemplate>
</Window.Resources>

<ListBox ItemsSource="{Binding Path=MyCollectionOfPanelVMs}" 
         ItemTemplate="{StaticResource myVMTemplate}" />

I haven't verified that this works.