Merge pull request #7 from RolandKoenig/6-allow-access-to-the-iservic…

…eprovider-from-a-usercontrol-class

Added GetServiceProvider as extension method to StyledElement

src/RolandK.AvaloniaExtensions.DependencyInjection.Tests/DependencyInjectionTests.cs

@@ -118,6 +118,29 @@ public Task Assign_ViewModel_by_CreateUsingDependencyInjectionExtension_after_at
             testWindow.Close();
         });
     }
+
+    [Fact]
+    public Task Create_Control_and_get_ServiceProvider_from_it()
+    {
+        return UnitTestApplication.RunInApplicationContextAsync(() =>
+        {
+            // Arrange
+            var myUserControl = new UserControl();
+
+            // Act
+            var testWindow = new TestRootWindow(myUserControl);
+            testWindow.Show();
+
+            var serviceProvider = myUserControl.GetServiceProvider();
+
+            // Assert
+            Assert.NotNull(serviceProvider);
+            Assert.NotNull(serviceProvider.GetService(typeof(IDummyService)));
+
+            // Cleanup
+            testWindow.Close();
+        });
+    }
 
     //*************************************************************************
     //*************************************************************************

src/RolandK.AvaloniaExtensions.DependencyInjection/ControlExtensions.cs

@@ -0,0 +1,36 @@
+using Avalonia;
+using Avalonia.Controls;
+
+namespace RolandK.AvaloniaExtensions.DependencyInjection;
+
+public static class ControlExtensions
+{
+    /// <summary>
+    /// Gets the <see cref="IServiceProvider"/> for this application.
+    /// Returns null, if the <see cref="IServiceProvider"/> could not be found.
+    /// </summary>
+    public static IServiceProvider? TryGetServiceProvider(this StyledElement control)
+    {
+        if(control.TryFindResource(DependencyInjectionConstants.SERVICE_PROVIDER_RESOURCE_KEY, out var resource) &&
+           resource is IServiceProvider serviceProvider)
+        {
+            return serviceProvider;
+        }
+        return null;
+    }
+
+    /// <summary>
+    /// Gets the <see cref="IServiceProvider"/> for this application.
+    /// </summary>
+    /// <exception cref="InvalidOperationException"><see cref="IServiceProvider"/> could not be found</exception>
+    public static IServiceProvider GetServiceProvider(this StyledElement control)
+    {
+        var serviceProvider = TryGetServiceProvider(control);
+        if (serviceProvider == null)
+        {
+            throw new InvalidOperationException(
+                $"{nameof(IServiceProvider)} not found! Call to {nameof(AppBuilderExtensions.UseDependencyInjection)} in Program.cs may be missing...");
+        }
+        return serviceProvider;
+    }
+}