Added ObservableValidator.ValidateAllProperties() API

Author: Sergio0694

Microsoft.Toolkit.Mvvm/ComponentModel/ObservableValidator.cs

@@ -9,6 +9,7 @@
 using System.ComponentModel.DataAnnotations;
 using System.Diagnostics.Contracts;
 using System.Linq;
+using System.Reflection;
 using System.Runtime.CompilerServices;
 
 namespace Microsoft.Toolkit.Mvvm.ComponentModel
@@ -382,6 +383,30 @@ IEnumerable<ValidationResult> GetAllErrors()
         [Pure]
         IEnumerable INotifyDataErrorInfo.GetErrors(string? propertyName) => GetErrors(propertyName);
 
+        /// <summary>
+        /// Validates all the properties in the current instance and updates all the tracked errors.
+        /// If any changes are detected, the <see cref="ErrorsChanged"/> event will be raised.
+        /// </summary>
+        /// <remarks>
+        /// Only public instance properties (excluding custom indexers) that have at least one
+        /// <see cref="ValidationAttribute"/> applied to them will be validated. All other
+        /// members in the current instance will be ignored. None of the processed properties
+        /// will be modified - they will only be used to retrieve their values and validate them.
+        /// </remarks>
+        protected void ValidateAllProperties()
+        {
+            foreach (PropertyInfo propertyInfo in
+                GetType()
+                .GetProperties(BindingFlags.Instance | BindingFlags.Public)
+                .Where(static p => p.GetIndexParameters().Length == 0 &&
+                                   p.GetCustomAttributes<ValidationAttribute>(true).Any()))
+            {
+                object? propertyValue = propertyInfo.GetValue(this);
+
+                ValidateProperty(propertyValue, propertyInfo.Name);
+            }
+        }
+
         /// <summary>
         /// Validates a property with a specified name and a given input value.
         /// If any changes are detected, the <see cref="ErrorsChanged"/> event will be raised.

UnitTests/UnitTests.Shared/Mvvm/Test_ObservableValidator.cs

@@ -298,6 +298,47 @@ public void Test_ObservableValidator_ClearErrors()
             Assert.IsTrue(events[1].PropertyName == nameof(Person.Name));
         }
 
+        [TestCategory("Mvvm")]
+        [TestMethod]
+        public void Test_ObservableValidator_ValidateAllProperties()
+        {
+            var model = new PersonWithDeferredValidation();
+            var events = new List<DataErrorsChangedEventArgs>();
+
+            model.ErrorsChanged += (s, e) => events.Add(e);
+
+            model.ValidateAllProperties();
+
+            Assert.IsTrue(model.HasErrors);
+            Assert.IsTrue(events.Count == 2);
+
+            // Note: we can't use an index here because the order used to return properties
+            // from reflection APIs is an implementation detail and might change at any time.
+            Assert.IsTrue(events.Any(e => e.PropertyName == nameof(Person.Name)));
+            Assert.IsTrue(events.Any(e => e.PropertyName == nameof(Person.Age)));
+
+            events.Clear();
+
+            model.Name = "James";
+            model.Age = 42;
+
+            model.ValidateAllProperties();
+
+            Assert.IsFalse(model.HasErrors);
+            Assert.IsTrue(events.Count == 2);
+            Assert.IsTrue(events.Any(e => e.PropertyName == nameof(Person.Name)));
+            Assert.IsTrue(events.Any(e => e.PropertyName == nameof(Person.Age)));
+
+            events.Clear();
+
+            model.Age = -10;
+
+            model.ValidateAllProperties();
+            Assert.IsTrue(model.HasErrors);
+            Assert.IsTrue(events.Count == 1);
+            Assert.IsTrue(events.Any(e => e.PropertyName == nameof(Person.Age)));
+        }
+
         public class Person : ObservableValidator
         {
             private string name;
@@ -331,6 +372,25 @@ public int Age
             }
         }
 
+        public class PersonWithDeferredValidation : ObservableValidator
+        {
+            [MinLength(4)]
+            [MaxLength(20)]
+            [Required]
+            public string Name { get; set; }
+
+            [Range(18, 100)]
+            public int Age { get; set; }
+
+            // Extra property with no validation
+            public float Foo { get; set; } = float.NaN;
+
+            public new void ValidateAllProperties()
+            {
+                base.ValidateAllProperties();
+            }
+        }
+
         /// <summary>
         /// Test model for linked properties, to test <see cref="ObservableValidator.ValidateProperty(object?, string?)"/> instance.
         /// See https://github.com/windows-toolkit/WindowsCommunityToolkit/issues/3665 for the original request for this feature.