Remember earlier when I said that setting the user control's DataContext to itself is a mistake? rev2023.3.3.43278. 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. The bindings in our FieldUserControl have a value for the Path, which specifies the target, but what is the source? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. The the datacontext of MyUsercontrol is inherited from mainwindow and is MainWindoViewModel. Instead, nest it one Element deep in the XAML, in your case, the StackPanel. This is very simple to do, and used in a lot of web applications like Twitter. The only major issue with declaring the object in the XAML is that any error thrown during the VM construction, will be eaten by a XAML parsing error. We have switched off to using a DI like MEF to have inject the VM into the View's DataContext at Load. This blog post provides step-by-step instructions for creating a user control, which exposes bindable properties, in WPF and Silverlight. This article has been fully translated into the following languages: The TextBlock control - Inline formatting, How-to: ListView with left aligned column names, TreeView, data binding and multiple templates, How-to: Creating a complete Audio/Video player, Multi-threading with the BackgroundWorker, Improving SnakeWPF: Making it look more like a game, Improving SnakeWPF: Adding a high score list. ncdu: What's going on with this second size column? So we add another dependency property to our user control. ViewModel HierarchicalDataTemplate a Treeview ( HierarchicalDataTemplate.Itemsource ) . xaml, TextBlockDataContext /// Gets or sets the Label which is displayed next to the field, /// Identified the Label dependency property, /// Gets or sets the Value which is being displayed. The current character count is obtained by binding to the Text.Length property directly on the TextBox control, which uses the lower part of the user control. 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. Window.DataContext , xamlUserControlbaseContainer, UserControlInitializeComponentbaseContainer.DataContext = . Program looks like the following when run, first text is blank followed by TextBlock with working binding: The UserControl is actually inheriting the DataContext from its parent element. In your code you have an AllCustomers property on your View Model but you are binding to Customers. Put the DataContext binding here and bind it to the UserControl. 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 If you do set it to self and you place this control on a Window or another control, it will not inherit the Windows DataContext. the ElementName property. 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. ( A girl said this after she killed a demon and saved MC). How to react to a students panic attack in an oral exam? Learn More ProfileText Sign in Gallery MSDN Library Forums Get started for free Ask a question Question. combo box inside a user control disappears when style is applied in wpf. () . 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. wpf3 . I know this has been answered but none of the explanations give an Understanding of DataContext and how it works. In our MainPage.xaml we have attempted to bind the Value property of the FieldUserControl to the Height property on our model object. The post covers dependency properties, and how to manage DataContext inheritance. the focus to another control before the change is applied. This preserves the Inheritance. This works, but specifying ElementName every time seems unnecessary. We'll find out later that this is a mistake - but for now let's just go with it! That means, after initializing the application I lost my DataContext from the UserControl, but have the DataContext from the Window at both, Window and UserControl. I set my viewmodel datacontext the same way I observed Blend4 to. In answer to your question #2 . , MainWindow2 Is there a proper earth ground point in this switch box? on the window and then a more local and specific DataContext on e.g. It could potentially be added. DependencyProperty not updating on PropertyChanged, WPF user control properties not binding or updating, PropertyChanged event null after data context is set, Binding Dependency Property of UserControl to MainWindow ViewModel in WPF, Binding custom control to parent datacontext property, Databinding partially working to custom dependency property in UserControl, Dependency Property reset after setting DataContext, Binding to the UserControl which contains the ItemControl data, DataContext on CommandParameter differs from DataContext on Command itself. Find centralized, trusted content and collaborate around the technologies you use most. If a law is new but its interpretation is vague, can the courts directly ask the drafters the intent and official interpretation of their law? The control is populated with design-time data via its properties. I would prefer to do it in a xaml file anyway. The model property value is still displayed but the label is not. Whether using WPF, ASP.NET, WinForms, HTML5 or Windows 10, DevExpress tools help you build and deliver your best in the shortest time possible. Let's try illustrating that with a simple
There are 3 ways to hook-up View with ViewModel. We do this by adding a Label property to our FieldUserControl. IsDesignTimeCreatable=True}", Last Visit: 31-Dec-99 19:00 Last Update: 3-Mar-23 21:59, Design-Time Attributes in the Silverlight Designer, Walkthrough: Using Sample Data in the Silverlight Designer, Sample Data in the WPF and Silverlight Designer, How can I use any Path Drawing as a progressBar in WPF. We have just found out why! It can be set for any FrameworkElement and specifies the design-time DataContext for a control and its children. I'm board member of FINOS, which is encouraging open source collaboration in the financial sector. We already have the Label dependency property, we now add a Value property: This value property is bound to the user control UI as follows: The idea here is that the exposed Value property 'relays' the value of the binding in our MainPage.xaml, which now has a binding which tells us which model object property is being displayed in our user control: If you compile and run this code you will find that it doesn't work! With the above code in place, all we need is to consume (use) the User control within our Window. UserControl.DataContext Main View Main View DataContext Window.DataContext Main View UserControl DataContext Main View UserContext DataContext View ** This is where things get a bit tricky! This was by far the most helpful answer here since it does not break the datacontext Inheritance. The most important of the design-time attiributes is d:DataContext. Is a PhD visitor considered as a visiting scholar? Using sample data ensures proper layout and allows one to see data-specific effects (e.g., effects of very long stings in bound properties) without running the application. And for second question, I think using ElementName or AncestorBinding is best way to bind to UserControl's properties. Connect and share knowledge within a single location that is structured and easy to search. Has 90% of ice around Antarctica disappeared in less than a decade? This is definitely the best solution! With the DataContext of the control now set to itself, our label is now working: However, now our value has disappeared! What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? B, TextB This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL), General News Suggestion Question Bug Answer Joke Praise Rant Admin. This makes direct use of the d:DataContext attribute in user controls impossible and one needs to resolve to a trick. Use of this site constitutes acceptance of our, Copyright 1998-2023 Developer Express Inc. All trademarks or registered trademarks are property of their respective owners, Only Visible to You and DevExpress Support. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Each of them use data binding for all of the information needed - the Title and MaxLength comes from the Code-behind properties, which we have defined in as regular properties on a regular class. I should write this every time? This is not such a big problem, we were going to have to change that anyway, a hard-coded binding to the Shoesize property means that we cannot re-use this control to edit other properties of the model object. Why? Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? Do I need a thermal expansion tank if I already have a pressure tank? Window.DataContextWindow, I need a DataContext for the Window and another one for the UserControl. When building user interfaces you will often find . A place where magic is studied and practiced? Put the DataContext binding here and bind it to the UserControl. 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 By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. DataContext is inherited to all lower Elements of the XAML and to all the XAML of UserControls unless it is overwritten somewhere. It makes sure that your View is hooked up with ViewModel. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? This is a new one for me. Sample Data in the WPF and Silverlight Designer. Using Kolmogorov complexity to measure difficulty of problems? How to define 'Attached property' as 'SelectedValuePath' in ComboBox? DataContextWPF. The post covers dependency properties, and how to manage DataContext inheritance. More info about Internet Explorer and Microsoft Edge, In the Sub Window is a UserControl Window. When one designs WPF UI elements in Microsoft Visual Studio or Blend, it is very beneficial to see them populated with sample data. The model is created with ado.net entity framework. Find centralized, trusted content and collaborate around the technologies you use most. I have a custom component that declares a DependencyProperty. Quote: according to most of the opinions online, giving a Usercontrol a viewmodel of its own is an extremely bad idea. If you create a binding in XAML but do not specify the source (which is probably the most common use case), the source will be set to the DataContext of the control the binding has been specified on. When building user interfaces you will often find yourself repeating the same UI patterns across your application. As a result, the DataContext for FieldUserControl and all of its child elements is also ModelObject. A user control acts much like a WPF Window - an area where you can place other controls, and then a Code-behind file where you can interact with these controls. The first step is to create a new user control, FieldUserControl, and move our XAML into there: We can now replace the XAML we have moved with an instance of this user control: Compiling and running this code proves that this still works; we can see the model property and edit it: For trivial user controls this is all we need to do. save save datacontext . If the control is depending on some VM or is tightly coupled / depends on being placed into a specific context to work then it isn't a "control". As an example, let's consider the progress report user control shown in figures 1 and 2. Why is there a voltage on my HDMI and coaxial cables? Silverlight - Setting DataContext in XAML rather than in constructor? For example, I may have a complex entry form with a lot of Xaml. TestControlDataContextthis.DataContext This problem can be fixed by setting the DataContext of the FieldUserControl's root element to itself. WPF UserControl doesn't inherit parent DataContext, Styling contours by colour and by line thickness in QGIS. WPFUserControlBinding C# UserControlBinding UserControl <Button Content= "OK" Width= "75" Margin= "15 8 15 8" x:Name= "ButtonOk" /> ButtonOk CommandWindowBinding xaml .csDependencyProperty We can now create multiple instances of FieldUserControl to edit different properties: With an update of the FieldUserControl styling, the result looks like this: We now have a truly re-useable user control!