Handle tab controls when focusing on error

RequiredValidationRule.cs

@@ -1,25 +0,0 @@
-using System.Globalization;
-using System.Windows.Controls;
-
-namespace ChrisKaczor.Wpf.Validation
-{
-    public class RequiredValidationRule : ValidationRule
-    {
-        public static string GetErrorMessage(object? fieldValue)
-        {
-            var errorMessage = string.Empty;
-
-            if (fieldValue == null || string.IsNullOrWhiteSpace(fieldValue.ToString()))
-                errorMessage = "Required";
-
-            return errorMessage;
-        }
-
-        public override ValidationResult Validate(object value, CultureInfo cultureInfo)
-        {
-            var error = GetErrorMessage(value);
-
-            return !string.IsNullOrEmpty(error) ? new ValidationResult(false, error) : ValidationResult.ValidResult;
-        }
-    }
-}

WindowExtensions.cs

@@ -1,15 +1,17 @@
-using System.Collections.Generic;
+using DebounceThrottle;
+using System.Collections.Generic;
 using System.ComponentModel;
 using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Data;
 using System.Windows.Media;
+using System.Windows.Threading;
 
-namespace ChrisKaczor.Wpf.Validation
+namespace ChrisKaczor.Wpf.Validation;
+
+public class BindingExpressionInfo
 {
-    public class BindingExpressionInfo
-    {
     public FrameworkElement FrameworkElement { get; }
     public BindingExpression BindingExpression { get; }
 
@@ -18,10 +20,10 @@ namespace ChrisKaczor.Wpf.Validation
         FrameworkElement = frameworkElement;
         BindingExpression = bindingExpression;
     }
-    }
+}
 
-    public static class WindowExtensions
-    {
+public static class WindowExtensions
+{
     public static List<BindingExpressionInfo> GetBindingExpressions(this DependencyObject parent)
     {
         return GetBindingExpressions(parent, null);
@@ -62,11 +64,12 @@ namespace ChrisKaczor.Wpf.Validation
                 if (dependencyObject is FrameworkElement frameworkElement)
                 {
                     // Get the list of properties
-                        IEnumerable<DependencyProperty> dependencyProperties = (from PropertyDescriptor propertyDescriptor in TypeDescriptor.GetProperties(frameworkElement)
-                                                                                select DependencyPropertyDescriptor.FromProperty(propertyDescriptor)
-                                                                                    into dependencyPropertyDescriptor
-                                                                                    where dependencyPropertyDescriptor != null
-                                                                                    select dependencyPropertyDescriptor.DependencyProperty).ToList();
+                    IEnumerable<DependencyProperty> dependencyProperties = TypeDescriptor.GetProperties(frameworkElement)
+                        .Cast<PropertyDescriptor>()
+                        .Select(DependencyPropertyDescriptor.FromProperty)
+                        .Where(dependencyPropertyDescriptor => dependencyPropertyDescriptor != null)
+                        .Select(dependencyPropertyDescriptor => dependencyPropertyDescriptor.DependencyProperty)
+                        .ToList();
 
                     // Loop over each dependency property in the list
                     foreach (var dependencyProperty in dependencyProperties)
@@ -87,19 +90,26 @@ namespace ChrisKaczor.Wpf.Validation
         }
     }
 
-        public static void UpdateAllSources(this DependencyObject window, IEnumerable<BindingExpressionInfo> bindingExpressions)
+    public static void UpdateAllSources(this DependencyObject _, IEnumerable<BindingExpressionInfo> bindingExpressions)
     {
         foreach (var expression in bindingExpressions)
             expression.BindingExpression.UpdateSource();
     }
 
-        public static void ClearAllValidationErrors(this DependencyObject window, IEnumerable<BindingExpressionInfo> bindingExpressions)
+    public static void ClearAllValidationErrors(this DependencyObject _, IEnumerable<BindingExpressionInfo> bindingExpressions)
     {
         foreach (var expression in bindingExpressions)
             System.Windows.Controls.Validation.ClearInvalid(expression.BindingExpression);
     }
 
     public static bool IsValid(this DependencyObject window)
+    {
+        return IsValid(window, null);
+    }
+
+    private static readonly DebounceDispatcher FocusDispatcher = new(50);
+
+    public static bool IsValid(this DependencyObject window, TabControl? tabControl)
     {
         // Get a list of all framework elements and binding expressions
         var bindingExpressions = window.GetBindingExpressions();
@@ -117,10 +127,31 @@ namespace ChrisKaczor.Wpf.Validation
         // Get the first framework element with an error
         var firstErrorElement = bindingExpressions.First(b => b.BindingExpression.HasError).FrameworkElement;
 
+        if (tabControl == null)
+        {
             // Set focus
             firstErrorElement.Focus();
 
             return false;
         }
+
+        // Loop over each tab item
+        foreach (TabItem tabItem in tabControl.Items)
+        {
+            // Cast the content as visual
+            var content = (Visual) tabItem.Content;
+
+            // See if the control with the error is a descendant 
+            if (!firstErrorElement.IsDescendantOf(content))
+                continue;
+
+            // Select the tab
+            tabItem.IsSelected = true;
+        }
+
+        var dispatcher = Dispatcher.CurrentDispatcher;
+        FocusDispatcher.Debounce(() => dispatcher.Invoke(() => firstErrorElement.Focus()));
+
+        return false;
     }
 }

Wpf.Validation.csproj

@@ -14,6 +14,9 @@
 		<PackageReadmeFile>README.md</PackageReadmeFile>
 		<AssemblyName>ChrisKaczor.Wpf.Validation</AssemblyName>
 	</PropertyGroup>
+	<ItemGroup>
+	  <PackageReference Include="DebounceThrottle" Version="2.0.0" />
+	</ItemGroup>
 	<ItemGroup>
 		<None Update="README.md">
 			<Pack>True</Pack>