Goal
To have a DataGrid in my MainWindow.xaml contain whatever I add in another Window.xaml's ViewModel Property.
I am looking how to display the exact information in my MainWindow's DataGrid.
Background Information
MainWindow.xaml has a DataContext to ViewModel InspectionViewModel.vb
Window.xaml has a DataContext to ViewModel DamagedItemViewModel.vb
My ViewModel contains an ObservableCollection of my Model: DamagedItemModel.vb
I want to be able to gather whatever is on my ObservableCollection and put it into my MainWindow's DataGrid's ItemSource. Is this possible?
In my DamagedItemViewModel I shared the public property so that I could access it from my InspectionViewModel.
InspectionViewModel Modifications
I made my ViewModel inherit INotifyPropertyChanged and added the same ObservableCollection property that my DamagedItemViewModel contained. Once the user was finished with the Window.xaml, I just assign the DamagedItemViewModel.DamagedItems to my InspectionViewModel.DamagedItems.
DamagedItems = DamagedItemViewModel.DamagedItems
Related
I have a main window that contains two usercontrols.
The first usercontrol have a tabcontrol.How can I notify the second usercontrol when a tabitem is selected in the first usercontrol.
If you're using MVVM approach, you'll probably have bound SelectedIndex of your TabControl to a ViewModel property. In that case your second usercontrol will bind to the same (or some other) property of the ViewModel and will be notified through standard notification mechanisms (such as INotifyPropertyChanged or DependencyProperty etc.).
In case, you are not using ViewModels and coding directly behind your Window, you can listen to SelectionChanged event and update your second usercontrol therein.
I am developing an application following the MVVM model and writing my code in VB.
I have created my own UserControl, let's call it 'Arrow', which has a property in its ViewModel called 'Angle'. In my main window I have a ListBox which is bound to a collection and each ListItem will be an Arrow.
How can I bind an angle value in the ListBox's DataSource to the Angle property of each instance of my UserControl please?
From my research so far it looks as if I need to create a DependencyProperty for Angle. If this is the case do I create this in my ViewModel, in the code-behind the XAML or elsewhere?
I'm sure this is simple when you know how!
The DependencyProperty would be defined in the UserControl (the code-behind). You'd then bind that property to the property in the ViewModel
In my WPF application, I have a usercontrol library. In this library, I have a listview control along with textbox and button controls.
I have placed this usercontrol in a WPF window form. How can I retrieve the listviewitems of my usercontrol in this WPF window form?
You ask a very general question. There are dozens of ways to do that, depends on your needs. For example: when you place you UserControl within the Window - you should name it (e.g. . Then, within the UserControl, you can have a public function, or a public getter, which will return the items (it is the 'Items' property of the ListView).
Another way is binding. If you have a ViewModel, or any other class as the DataContext, you can bind the ItemsSource of the ListView to a collection on your ViewModel. Unless you change the DataContext of the UserControl - it will have the same DataContext as the main Window.
I have a form with two different UserControls - one that contains a Telerik RadGridView and the other that that contains a Telerik DataForm.
The grid usercontrol is bound to a ViewModel that includes a property that exposes the Items collection that the grid is bound to.
When I bind the form to that property, everything works fine.
But I need to access additional info in the form control that really doesn't belong in the grid control's viewmodel.
So I thought I'd add a property to the form usercontrol, and bind it to the items collection:
<local:FormControl x:Name="formControl"
ItemsSource="{Binding items}"
/>
In the form's code-behind, I added a normal property:
private object itemsSource;
public object ItemsSource
{
get { return this.itemsSource; }
set { this.itemsSource = value; }
}
And this didn't work, of course. I got errors about having to use a DependencyProperty. Which I thought was reassuring - the page was actually trying to bind to the property I thought it should.
So I converted this to a DependencyProperty:
public static DependencyProperty ItemsSourceProperty =
DependencyProperty.Register("ItemsSource", typeof(object), typeof(FormControl));
public object ItemsSource
{
get { return GetValue(ItemsSourceProperty); }
set { SetValue(ItemsSourceProperty, value); }
}
That compiled and ran without errors. Except, of course, that the control's viewmodel didn't have any items. So next was to try to pass the ItemsSource property to the form control's viewmodel:
public FormControl()
{
InitializeComponent();
this.DataContext = new FormControlVM(this.ItemsSource);
...
And this didn't work. ItemsSource was null when FormControl() was constructed. So I added a setItemsSource() method to the viewmodel, and called it in the ItemsSource property's set function. This didn't work, either. The xaml is apparently binding to the property, but it seems to do it without calling the property's set function.
So I decided to listen to the ValueChanged event, on the DependencyProperty:
public FormControl()
{
InitializeComponent();
this.DataContext = new FormControlVM();
DependencyPropertyDescriptor prop =
DependencyPropertyDescriptor.FromProperty(FormControl.ItemsSourceProperty, this.GetType());
prop.AddValueChanged(this, delegate
{
FormControlVM formControlVM = (FormControlVM)this.DataContext;
formControlVM.setItemsSource(this.ItemsSource);
});
...
And it's still not working. The ValueChanged delegate never seems to get called.
This seems like it should be a simple thing, but I've not been able to find examples on-line, and I've tried every combination I can conceive of.
Any ideas as to how I should handle this?
============ Additional info on the binding ============
Will was asking for info on the xaml that does the binding.
If I put this in page that contains the user control, binding the user control to the viewmodel of the page:
<local:FormControl x:Name="formControl"
Grid.Column="2"
DataContext="{Binding}"
/>
And then this in the user control, binding the form in the user control to the itemsCollection of the page's viewmodel:
<telerik:RadDataForm
ItemsSource="{Binding itemsCollection}"
Header="View Item:"
CommandButtonsVisibility="None"
AutoGenerateFields="False"
/>
Then everything works fine.
But the problem is that I can't bind the user control to the viewmodel of the page. I need to have the user control's viewmodel expose information that the page's viewmodel should not be seeing.
And I can't have the form in the user control reaching outside of the user control, binding to a property on the page's viewmodel. It's a violation of encapsulation, that will make using the user control on a different page much more complicated, and severely limit how I might modify the internals of the control in the future. (The page should not know anything about the controls within the user control, the controls within the user control should not know anything about the page.)
When I include the user control on a page, I want to bind the user control to a property of the page's viewmodel, and I want any controls within the user control to bind to properties of the user control, or of the user control's viewmodel.
I'd think this was a fairly common occurrence. But I've not been able to find any examples of how it might be done.
To restate the problem: I have a UserControl, that contains an embedded Telerik DataForm control. I need to bind the ItemsSource property of the embedded DataForm to a property of the DataContext of the page on which my UserControl is placed.
If the UserControl did not have its DataContext set, it would inherit the DataContext of the page, and I could easily bind the embedded DataForm's ItemsSource property to a property of it, but the UserControl has it's own DataContext.
If the UserControl was written to be used only on this page, I could bind the embedded DataForm's ItemsSource property to a property of the page, using RelativeSource binding. But this UserControl is intended to be used in a number of places, and cannot have silent dependencies on properties outside of the UserControl. I need to make the dependency explicit.
Creating a DependencyProperty on the UserControl is the right approach, but there's no need to try to replicate the property in the UserControl's viewmodel.
What I need to do is to
1: Add a DependencyProperty to the UserControl:
public QueryableCollectionView ItemsSource
{
get { return (QueryableCollectionView)GetValue(ItemsSourceProperty); }
set { SetValue(ItemsSourceProperty, value); }
}
public static readonly DependencyProperty ItemsSourceProperty =
DependencyProperty.Register("ItemsSource", typeof(QueryableCollectionView), typeof(FormControl));
Note: I do not need to implement a call-back function.
2: Bind the embedded DataForm's ItemsProperty to this new DependencyProperty of the UserControl, using RelativeSource binding:
<UserControl
...>
<telerik:RadDataForm
ItemsSource="{Binding Path=ItemsSource, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}"
/>
</UserControl>
3: Make the viewModel of the page visible, with the proper type (DataContext has type object):
public partial class MainWindow : Window
{
public MainWIndow()
{
this.InitializeComponent();
this.DataContext = new MainWindowVM();
}
public MainWindowVM viewModel
{ get { return this.DataContext as MainWindowVM; } }
}
4: On the page, bind the UserControl's new ItemsProperty DependencyProperty to the appropriate property of the page's viewmodel, again using RelativeSource binding:
<Window
...>
<local:FormControl
ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type telerik:RadPane}},Path=viewModel.items}"
/>
</Window>
My first question here on the Stack. Forgive me for the bad explanation in advance.
I am working on my first MVVM application (Silverlight). I have a custom user control that contains a ListBox to show navigation items. This control is placed in my main xaml page. I don't know if I need to create a composite view model (my main page view model) with a view model especially for the custom control in it or if there is some way to elevate the ListBox properties that I need to bind to.
Through XAML I don't know how to bind, let's say, the ItemsSource property of the ListBox inside the custom control to my main page viewmodel. Basically, I'm at the point that I am questioning my design decision for trying to bind the custom control through my main page view model.
What I have done so far is create dependency properties for the custom control and try to tunnel those dependency properties down to the ListBox properties. I've achieved success with this method for ItemsSource but am having issues with SelectedItem.
Even if I do get SelectedItem to work, it still feels Wrong. Thanks for any advice in advance.
The UserControl should inherit the DataContext from its parent control, unless you are setting it directly. You can then bind to the properties on your view model from your UserControl.
If you would like to create a ViewModel specifically for the UserControl, you can also do that. You would then expose it as a property on your main ViewModel, and bind to it in the MainPage. Example:
public class MainViewModel
{
public ChildViewModel ChildInfo { get; private set; }
}
And then in the view:
<Grid>
...
<lcl:ChildView DataContext="{Binding ChildInfo}" />
...
</Grid>
Your ChildViewModel would then contain properties like SelectedItem to bind your ListBox to.