Merge pull request #258 from CommunityToolkit/dev/fix-observableproperty-inherited-canexecute

Fix [ICommand] CanExecute with inherited generated property

Author: Sergio0694

CommunityToolkit.Mvvm.SourceGenerators/Input/ICommandGenerator.Execute.cs

@@ -723,11 +723,10 @@ private static bool TryGetCanExecuteMemberFromGeneratedProperty(
             ImmutableArray<string> commandTypeArguments,
             [NotNullWhen(true)] out CanExecuteExpressionType? canExecuteExpressionType)
         {
-            foreach (ISymbol memberSymbol in containingType.GetMembers())
+            foreach (ISymbol memberSymbol in containingType.GetAllMembers())
             {
                 // Only look for instance fields of bool type
-                if (memberSymbol is not IFieldSymbol fieldSymbol ||
-                    fieldSymbol is { IsStatic: true } ||
+                if (memberSymbol is not IFieldSymbol { IsStatic: false } fieldSymbol ||
                     !fieldSymbol.Type.HasFullyQualifiedName("bool"))
                 {
                     continue;

tests/CommunityToolkit.Mvvm.UnitTests/Test_ObservablePropertyAttribute.cs

@@ -645,6 +645,19 @@ public void Test_ObservableProperty_ModelWithAlsoBroadcastChangeAndDisplayAttrib
         CollectionAssert.AreEqual(new[] { nameof(model.SomeProperty) }, propertyNames);
     }
 
+    // See https://github.com/CommunityToolkit/dotnet/issues/257
+    [TestMethod]
+    public void Test_ObservableProperty_InheritedModelWithCommandUsingInheritedObservablePropertyForCanExecute()
+    {
+        InheritedModelWithCommandUsingInheritedObservablePropertyForCanExecute model = new();
+
+        Assert.IsFalse(model.SaveCommand.CanExecute(null));
+
+        model.CanSave = true;
+
+        Assert.IsTrue(model.SaveCommand.CanExecute(null));
+    }
+
     public abstract partial class BaseViewModel : ObservableObject
     {
         public string? Content { get; set; }
@@ -1037,4 +1050,20 @@ public sealed partial class ModelWithAlsoBroadcastChangeAndDisplayAttributeLast
         [Display(Name = "Foo bar baz")]
         private object? _someProperty;
     }
+
+    public abstract partial class BaseModelWithObservablePropertyAttribute : ObservableObject
+    {
+        [ObservableProperty]
+        private bool canSave;
+
+        public abstract void Save();
+    }
+
+    public partial class InheritedModelWithCommandUsingInheritedObservablePropertyForCanExecute : BaseModelWithObservablePropertyAttribute
+    {
+        [ICommand(CanExecute = nameof(CanSave))]
+        public override void Save()
+        {
+        }
+    }
 }