Moved EnableDataValdiation to AvaloniaPropertyMetadata

Support data validation in StyledProperty bindings

Co-Authored-By: Tom Edwards <109803929+tomenscape@users.noreply.github.com>

src/Avalonia.Base/AvaloniaObject.cs

@@ -776,11 +776,16 @@ namespace Avalonia
                     break;
             }
 
-            var metadata = property.GetMetadata(GetType());
+            UpdateDataValidationCore(property, value.Type, value.Error);
+        }
 
-            if (metadata.EnableDataValidation == true)
+        internal void UpdateDataValidationCore(AvaloniaProperty property,
+            BindingValueType state,
+            Exception? error)
+        {
+            if (property.GetMetadata(GetType()) is { EnableDataValidation: true })
             {
-                UpdateDataValidation(property, value.Type, value.Error);
+                UpdateDataValidation(property, state, error);
             }
         }
 

src/Avalonia.Base/AvaloniaObjectExtensions.cs

@@ -199,13 +199,11 @@ namespace Avalonia
             property = property ?? throw new ArgumentNullException(nameof(property));
             binding = binding ?? throw new ArgumentNullException(nameof(binding));
 
-            var metadata = property.GetMetadata(target.GetType()) as IDirectPropertyMetadata;
-
             var result = binding.Initiate(
                 target,
                 property,
                 anchor,
-                metadata?.EnableDataValidation ?? false);
+                property.GetMetadata(target.GetType()).EnableDataValidation ?? false);
 
             if (result != null)
             {

src/Avalonia.Base/AvaloniaProperty.cs

@@ -227,6 +227,7 @@ namespace Avalonia
         /// <param name="defaultBindingMode">The default binding mode for the property.</param>
         /// <param name="validate">A value validation callback.</param>
         /// <param name="coerce">A value coercion callback.</param>
+        /// <param name="enableDataValidation">Whether the property is interested in data validation.</param>
         /// <returns>A <see cref="StyledProperty{TValue}"/></returns>
         public static StyledProperty<TValue> Register<TOwner, TValue>(
             string name,
@@ -234,7 +235,8 @@ namespace Avalonia
             bool inherits = false,
             BindingMode defaultBindingMode = BindingMode.OneWay,
             Func<TValue, bool>? validate = null,
-            Func<AvaloniaObject, TValue, TValue>? coerce = null)
+            Func<AvaloniaObject, TValue, TValue>? coerce = null,
+            bool enableDataValidation = false)
                 where TOwner : AvaloniaObject
         {
             _ = name ?? throw new ArgumentNullException(nameof(name));
@@ -242,7 +244,8 @@ namespace Avalonia
             var metadata = new StyledPropertyMetadata<TValue>(
                 defaultValue,
                 defaultBindingMode: defaultBindingMode,
-                coerce: coerce);
+                coerce: coerce,
+                enableDataValidation: enableDataValidation);
 
             var result = new StyledProperty<TValue>(
                 name,
@@ -253,7 +256,7 @@ namespace Avalonia
             AvaloniaPropertyRegistry.Instance.Register(typeof(TOwner), result);
             return result;
         }
-        
+
         /// <inheritdoc cref="Register{TOwner, TValue}" />
         /// <param name="notifying">
         /// A method that gets called before and after the property starts being notified on an
@@ -267,6 +270,7 @@ namespace Avalonia
             BindingMode defaultBindingMode,
             Func<TValue, bool>? validate,
             Func<AvaloniaObject, TValue, TValue>? coerce,
+            bool enableDataValidation,
             Action<AvaloniaObject, bool>? notifying)
                 where TOwner : AvaloniaObject
         {
@@ -275,7 +279,8 @@ namespace Avalonia
             var metadata = new StyledPropertyMetadata<TValue>(
                 defaultValue,
                 defaultBindingMode: defaultBindingMode,
-                coerce: coerce);
+                coerce: coerce,
+                enableDataValidation: enableDataValidation);
 
             var result = new StyledProperty<TValue>(
                 name,

src/Avalonia.Base/AvaloniaPropertyMetadata.cs

@@ -13,10 +13,13 @@ namespace Avalonia
         /// Initializes a new instance of the <see cref="AvaloniaPropertyMetadata"/> class.
         /// </summary>
         /// <param name="defaultBindingMode">The default binding mode.</param>
+        /// <param name="enableDataValidation">Whether the property is interested in data validation.</param>
         public AvaloniaPropertyMetadata(
-            BindingMode defaultBindingMode = BindingMode.Default)
+            BindingMode defaultBindingMode = BindingMode.Default,
+            bool? enableDataValidation = null)
         {
             _defaultBindingMode = defaultBindingMode;
+            EnableDataValidation = enableDataValidation;
         }
 
         /// <summary>
@@ -31,6 +34,17 @@ namespace Avalonia
             }
         }
 
+        /// <summary>
+        /// Gets a value indicating whether the property is interested in data validation.
+        /// </summary>
+        /// <remarks>
+        /// Data validation is validation performed at the target of a binding, for example in a
+        /// view model using the INotifyDataErrorInfo interface. Only certain properties on a
+        /// control (such as a TextBox's Text property) will be interested in receiving data
+        /// validation messages so this feature must be explicitly enabled by setting this flag.
+        /// </remarks>
+        public bool? EnableDataValidation { get; private set; }
+
         /// <summary>
         /// Merges the metadata with the base metadata.
         /// </summary>
@@ -44,6 +58,8 @@ namespace Avalonia
             {
                 _defaultBindingMode = baseMetadata.DefaultBindingMode;
             }
+
+            EnableDataValidation ??= baseMetadata.EnableDataValidation;
         }
     }
 }

src/Avalonia.Base/DirectPropertyMetadata`1.cs

@@ -21,10 +21,9 @@ namespace Avalonia
             TValue unsetValue = default!,
             BindingMode defaultBindingMode = BindingMode.Default,
             bool? enableDataValidation = null)
-                : base(defaultBindingMode)
+                : base(defaultBindingMode, enableDataValidation)
         {
             UnsetValue = unsetValue;
-            EnableDataValidation = enableDataValidation;
         }
 
         /// <summary>
@@ -32,16 +31,6 @@ namespace Avalonia
         /// </summary>
         public TValue UnsetValue { get; private set; }
 
-        /// <summary>
-        /// Gets a value indicating whether the property is interested in data validation.
-        /// </summary>
-        /// <remarks>
-        /// Data validation is validation performed at the target of a binding, for example in a
-        /// view model using the INotifyDataErrorInfo interface. Only certain properties on a
-        /// control (such as a TextBox's Text property) will be interested in receiving data
-        /// validation messages so this feature must be explicitly enabled by setting this flag.
-        /// </remarks>
-        public bool? EnableDataValidation { get; private set; }
 
         /// <inheritdoc/>
         object? IDirectPropertyMetadata.UnsetValue => UnsetValue;
@@ -51,19 +40,9 @@ namespace Avalonia
         {
             base.Merge(baseMetadata, property);
 
-            var src = baseMetadata as DirectPropertyMetadata<TValue>;
+            if (baseMetadata is DirectPropertyMetadata<TValue> src)
-
-            if (src != null)
             {
-                if (UnsetValue == null)
+                UnsetValue ??= src.UnsetValue;
-                {
-                    UnsetValue = src.UnsetValue;
-                }
-
-                if (EnableDataValidation == null)
-                {
-                    EnableDataValidation = src.EnableDataValidation;
-                }
             }
         }
     }

src/Avalonia.Base/StyledElement.cs

@@ -46,6 +46,7 @@ namespace Avalonia
                 defaultBindingMode: BindingMode.OneWay,
                 validate: null,
                 coerce: null,
+                enableDataValidation: false,
                 notifying: DataContextNotifying);
 
         /// <summary>

src/Avalonia.Base/StyledPropertyMetadata`1.cs

@@ -16,11 +16,13 @@ namespace Avalonia
         /// <param name="defaultValue">The default value of the property.</param>
         /// <param name="defaultBindingMode">The default binding mode.</param>
         /// <param name="coerce">A value coercion callback.</param>
+        /// <param name="enableDataValidation">Whether the property is interested in data validation.</param>
         public StyledPropertyMetadata(
             Optional<TValue> defaultValue = default,
             BindingMode defaultBindingMode = BindingMode.Default,
-            Func<AvaloniaObject, TValue, TValue>? coerce = null)
+            Func<AvaloniaObject, TValue, TValue>? coerce = null,
-                : base(defaultBindingMode)
+            bool enableDataValidation = false)
+                : base(defaultBindingMode, enableDataValidation)
         {
             _defaultValue = defaultValue;
             CoerceValue = coerce;

tests/Avalonia.Base.UnitTests/AvaloniaPropertyTests.cs

@@ -198,6 +198,7 @@ namespace Avalonia.Base.UnitTests
                     defaultBindingMode: BindingMode.OneWay,
                     validate: null,
                     coerce: null,
+                    enableDataValidation: false,
                     notifying: FooNotifying);
 
             public int NotifyCount { get; private set; }