But DataContext isn't used in WinUI as often as it is in WPF, because WinUI has x:Bind, which doesn't need it. You will notice the same thing in Code-behind, where it simply inherits UserControl instead of Window. Yes that's a better solution to use DI for sure. There are 3 ways to hook-up View with ViewModel. Doesn't seem very good. This blog post provides step-by-step instructions for creating a user control, which exposes bindable properties, in WPF and Silverlight. Question. Solution 1. Why is this sentence from The Great Gatsby grammatical? This preserves the Inheritance. How to define 'Attached property' as 'SelectedValuePath' in ComboBox? How can I explain to my manager that a project he wishes to undertake cannot be performed by the team? the focus to another control before the change is applied. Is it a bug? The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. Where to find XAML namespace d="http://schemas.microsoft.com/expression/blend/2008" mapping library? I like it. What is the point of Thrower's Bandolier? This works, but specifying ElementName every time seems unnecessary. Put the DataContext binding here and bind it to the UserControl. WPF UserControl doesn't inherit parent DataContext, How Intuit democratizes AI development across teams through reusability. I know this is an old post but for anyone else coming herYou don't set up a VM for an individual control. Once it finds a non- null DataContext, that object is used for binding. Again, this is a DataContext issue, the binding in our user control is on a Shoesize property, whilst the DataContext is now the FieldUserControl instance. How is Jesus " " (Luke 1:32 NAS28) different from a prophet (, Luke 1:76 NAS28)? Simply put, it hierarchy, you can set a DataContext for the Window itself and then use it throughout all of the child controls. This is one of the most common anti-patterns in WPF. How is Jesus " " (Luke 1:32 NAS28) different from a prophet (, Luke 1:76 NAS28)? Not the answer you're looking for? Not the answer you're looking for? So we add another dependency property to our user control. The following articles describe design-time data binding in detail: The most important of the design-time attiributes is d:DataContext. using System; using System.ComponentModel; using System.Windows; namespace UserControlWorking { public partial class MainWindow : Window { DateHelper dtContext; public MainWindow () { InitializeComponent (); dtContext = new DateHelper (); DataContext=dtContext; dtContext.dateTime = System.DateTime.Now; dtContext.myString = "Date"; } private void This was by far the most helpful answer here since it does not break the datacontext Inheritance. There is however no TextFromParent property in that DataContext (because it is the MainWindow instance). It can be set for any FrameworkElement and specifies the design-time DataContext for a control and its children. MVVMUserControlxaml, TestViewModelTextBoxDataContext, TextBoxTextThisTextThisText**, TestViewModelUserControl.DataContextTextBoxViewModel, TestViewModelUserControlTextBoxGoogle[WPF]UserControl.DataContext, UserControl.DataContextMain ViewMain ViewDataContextWindow.DataContextMain ViewUserControlDataContextMain ViewUserContextDataContextView**, UserControl.DataContextViewDataContextMainViewModel.MainTextBoxViewDataContextDataContextThisText**, TestViewModelUserControlViewDataContext**, WPFMVVM. But from the Sub Window i can not set the datacontext with my data from the Sub Window. We'll do that by adding a reference to the namespace the UserControl lives in, in the top of the XAML code of your Window: After that, we can use the uc prefix to add the control to our Window like it was any other WPF control: Notice how we use the Title and MaxLength properties directly in the XAML. This is definitely the best solution! Why do small African island nations perform better than African continental nations, considering democracy and human development? (WinUI does still have Binding though.) The problem is that the DataContext from the Window inherits to the DataContext from the User Control. We have just found out why! Why doesn't work? For example, if one designs a simple progress report user control that has a progress bar with an overlaid message and a progress value, he might not discover problems with the design until he runs the application. Personally I would have the ViewModel call getcustomers() in the constructor. Mouse over the datagrid and press ctrl+shift. Creating & using a UserControl User controls, in WPF represented by the UserControl class, is the concept of grouping markup and code into a reusable container, so that the same interface, with the same functionality, can be used in several different places and even across several applications. We can now go ahead and bind the label text to this property: However, if you compile and run the above code, you'll find that it doesn't work. Should I do it in a viewmodel constructor? Since the window has a DataContext, which is It would be easy to just add this functionality to your regular Window, but since it could be useful to do in several places in your application, it makes sense to wrap it in an easily reusable UserControl. I need a DataContext for the Window and another one for the UserControl. Minimising the environmental effects of my dyson brain. Apologies. Let's try illustrating that with a simple or even in the loaded event this.Loaded += (sender, e) => { this.DataContext = this; }; That is very simple and elegant. Do I have to set it automatically? There's no default source for the DataContext property (it's simply null from the start), but since a DataContext is inherited down through the control So, in the controls constructor, we set DataContext of its child root element to the control itself. Control1 DataContext public partial class TestControl : UserControl { public TestControl () { InitializeComponent (); this.DataContext = new TestData (); } } And the view (no code behind at the moment): The problem is that no data is displayed simply because the data context is not set. We could cut and paste our current XAML, but this will only cause maintenance issues in future. Quote: according to most of the opinions online, giving a Usercontrol a viewmodel of its own is an extremely bad idea. Before we dive into the code, let's have a look at the end result that we're going for: Here's the code for the user control itself: The markup is pretty straight forward: A Grid, with two columns and two rows. The region and polygon don't match. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? Bindings have both a source and a target; where the binding framework is responsible for handling change notifications from the source and (optionally) the target, keeping the two synchronized. You'll also find a whole host of posts about previous technology interests including iOS, Swift, WPF and Silverlight. It could potentially be added. At the same time, when we design the window hosting our user control, the window constructor again will not be executed, but the control constructor will. In your code you have an AllCustomers property on your View Model but you are binding to Customers. Dim vm As New WpfApp030.ViewModel Me.DataContext = vm Call (New Window030Child With {.DataContext = vm}).Show () End Sub End Class Namespace WpfApp030 Public Class ViewModel Implements INotifyPropertyChanged Private _info As String Public Property Info As String Get Return Me._info End Get Set (value As String) Me._info = value OnPropertyChanged Since each control has its own DataContext property, You can also try To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Here's the full code sample for our window: With that, we can reuse this entire piece of functionality in a single line of code, as illustrated in this example where we have the limited text input control two times. However, we should recall that when a user control is designed in the Design view, the designer does not execute its constructor (though it will execute constructors of all its child elements). We are using the MVVM module of DevExpress. To me, it is personal preference or usage-specific. This means that the FieldUserControl still inherits its parent's DataContext, so bindings to our model object will work. This problem can be fixed by setting the DataContext of the FieldUserControl's root element to itself. Whether using WPF, ASP.NET, WinForms, HTML5 or Windows 10, DevExpress tools help you build and deliver your best in the shortest time possible. Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages. For the desperate souls, who are trying to make pdross's answer work and can't: It's missing an essential detail - Path=DataContext. The attached UseControlDesignTimeDataBinding.zip file contains the full source code for the tip. The post covers dependency properties, and how to manage DataContext inheritance. We'll find out later that this is a mistake - but for now let's just go with it! Instead you should set the DataContext in the first child UI element in your control. Where to find XAML namespace d="http://schemas.microsoft.com/expression/blend/2008" mapping library? How to define 'Attached property' as 'SelectedValuePath' in ComboBox? Window.DataContext My View/ViewModels typically follow this sequence of events: My ViewModel is instanced from the XAML codebehind (sorry this is in VB.NET, have not gotten around to learning C# well enough to trust myself with it): But that did not work out like I wanted it to. About an argument in Famine, Affluence and Morality. What is the best way to do something like this? Asking for help, clarification, or responding to other answers. As already shown, the final result looks like this: Placing commonly used interfaces and functionality in User Controls is highly recommended, and as you can see from the above example, they are very easy to create and use. View of the same progress report control in the Visual Studio designer when it is design-time data bound to sample data, Figure 3. I would prefer to do it in a xaml file anyway. For example: This works well for the content of WPF/Silverlight Windows and Pages. Find centralized, trusted content and collaborate around the technologies you use most. allows you to specify a basis for your bindings. Is there a proper earth ground point in this switch box? By setting the UserControl DataContext to itself, this overwrites the DataContext and breaks Inheritance. . . and not specifying ElementNames, but that doesn't seem like a clean solution to me either. The DataContext is most often set to a view model or business / model object, as in our case where the top level control, the MainPage, has its DataContext set to an instance of ModelObject.