Added new kb article accessing-controls-inside-dynamic-radpopup-data-template

Author: KB Bot

knowledge-base/accessing-controls-inside-dynamic-radpopup-data-template.md

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+---
+title: Accessing Controls Inside Dynamic Popup Loaded from DataTemplate in ResourceDictionary
+description: Learn how to dynamically load Popup content from a DataTemplate in a ResourceDictionary in UI for .NET MAUI and update the controls inside.
+type: how-to
+page_title: Updating Controls Inside Popup Loaded Dynamically from DataTemplate in ResourceDictionary
+meta_title: Updating Controls Inside Popup Loaded Dynamically from DataTemplate in ResourceDictionary
+slug: accessing-controls-inside-dynamic-radpopup-data-template
+tags: popup, datatemplate, radpopup, maui, binding
+res_type: kb
+---
+
+## Environment
+
+| Version | Product | Author | 
+| --- | --- | ---- | 
+| 11.0.1 | Popup for .NET MAUI | [Dobrinka Yordanova](https://www.telerik.com/blogs/author/dobrinka-yordanova) | 
+
+## Description
+
+I want to load a `RadPopup` dynamically using a `DataTemplate` defined in a `ResourceDictionary` and access or update the controls (e.g., `Label`) inside the template. However, accessing controls using `x:Name` is not working. I need a solution to update the control's properties, such as the `Text` property of a `Label`, when the popup opens.
+
+This knowledge base article also answers the following questions:
+- How to bind and update controls in a `RadPopup` `DataTemplate` in .NET MAUI?
+- How to dynamically modify the content of `RadPopup` in .NET MAUI?
+- How to set control properties inside `RadPopup` using bindings or code?
+
+## Solution
+
+To achieve this, you can use one of two approaches: 
+* Binding the controls to a `ViewModel`.
+* Programmatically accessing the controls inside the `DataTemplate`. 
+
+### Option 1: Using Binding with ViewModel
+
+Use bindings to update the control properties inside the `DataTemplate`. Bind the `Label`'s `Text` property to a `ViewModel` and ensure the binding mode is set to `TwoWay`.
+
+**1.** Define a `ViewModel` with a property for binding:
+
+```csharp
+public class ViewModel : NotifyPropertyChangedBase
+{
+    private string myValue;
+
+    public ViewModel()
+    {
+        this.myValue = "hello";
+    }
+
+    public string MyValue
+    {
+        get => this.myValue;
+        set => this.UpdateValue(ref this.myValue, value);
+    }
+}
+```
+
+**2.** Set the `BindingContext` in your code-behind:
+
+```csharp
+public partial class MainPage : ContentPage
+{
+    ViewModel vm;
+
+    public MainPage()
+    {
+        InitializeComponent();
+        this.vm = new ViewModel();
+        this.BindingContext = this.vm;
+    }
+
+    private void CheckBoxIsCheckedChanged(object sender, IsCheckedChangedEventArgs e)
+    {
+        if (e.NewValue == true)
+        {
+            this.popup.IsOpen = true;
+            this.vm.MyValue = "value changed";
+        }
+    }
+}
+```
+
+**3.** Define the `DataTemplate` in XAML and bind the `Label`'s `Text` property:
+
+```xml
+<DataTemplate x:Key="PopupTemplate">
+    <telerik:RadBorder CornerRadius="8"
+                       BackgroundColor="#F9F9F9"
+                       BorderColor="Red"
+                       BorderThickness="1"
+                       WidthRequest="300"
+                       Padding="12">
+        <VerticalStackLayout Spacing="8">
+            <Label Text="{Binding MyValue, Mode=TwoWay}" />
+        </VerticalStackLayout>
+    </telerik:RadBorder>
+</DataTemplate>
+```
+
+### Option 2: Accessing Controls Programmatically
+
+Directly access the controls inside the `DataTemplate` programmatically and update their properties.
+
+**1.** Define the `DataTemplate` in XAML:
+
+```xml
+<DataTemplate x:Key="PopupTemplate">
+    <telerik:RadBorder CornerRadius="8"
+                       BackgroundColor="#F9F9F9"
+                       BorderColor="Red"
+                       BorderThickness="1"
+                       WidthRequest="300"
+                       Padding="12">
+        <VerticalStackLayout Spacing="8">
+            <Label />
+        </VerticalStackLayout>
+    </telerik:RadBorder>
+</DataTemplate>
+```
+
+**2.** In the code-behind, dynamically load the content and update the control properties:
+
+```csharp
+private void CheckBoxIsCheckedChanged(object sender, IsCheckedChangedEventArgs e)
+{
+    if (e.NewValue == true)
+    {
+        this.popup.IsOpen = true;
+        var dataTemplate = this.myPage.Resources["PopupTemplate"] as DataTemplate;
+
+        var popupcontent = dataTemplate.CreateContent() as View;
+        this.popup.Content = popupcontent;
+
+        List<IVisualTreeElement> items = (List<IVisualTreeElement>)this.popup.Content.GetVisualTreeDescendants();
+        foreach (IVisualTreeElement myControl in items)
+        {
+            if (myControl is Label)
+            {
+                Label control = (Label)myControl;
+                control.Text = "popup content has been changed when opened";
+                return;
+            }
+        }
+    }
+}
+```
+
+### Key Considerations:
+
+- Accessing controls inside a `DataTemplate` using `x:Name` is not possible due to the general behavior of the MAUI framework.
+- Use bindings if you want to follow MVVM principles.
+- For direct control access, ensure the `DataTemplate` content is created and assigned to the popup before attempting to modify controls.
+
+## See Also
+
+- [.NET MAUI Popup Documentation](https://docs.telerik.com/devtools/maui/controls/popup/overview)