Merge branch 'bugfix/ReverseTopicMappingService-records' into develop

The `TopicMappingService` takes a very permissive approach to mapping; if the target property doesn't exist on the source `Topic`, or cannot be mapped, it fails silently. By contrast, the `ReverseTopicMappingService` is much more conservative, since the results are (potentially) invasive, resulting in updating the underlying persistence store. As a result, if the source binding model has properties that cannot be mapped, or don't correspond to attributes on the `ContentTypeDescriptor`, an exception is thrown. This helps warn implementers about design flaws that might result in data loss.

This introduces problems with C# 9.0 record types, however, as the compiler dynamically generates a `EqualityContract` property for each record. But as there isn't an `EqualityContract` attribute on the `ContentTypeDescriptor`, the `BindingModelValidator` will throw an exception.

To mitigate that, a hard-coded exception is added to both the `ReverseTopicMappingService` and the `BindingModelValidator` to ignore properties named `EqualityContract`, treating them as though they are decorated with the `[DisableMapping]` attribute. This effectively allows binding models to be implemented as record types, just as we prefer for view models. And since we implemented our stock `OnTopic.ViewModels` as records, it also allows binding models to derive from those models.

Author: JeremyCaney

OnTopic.Tests/BindingModels/RecordTopicBindingModel.cs

@@ -0,0 +1,31 @@
+/*==============================================================================================================================
+| Author        Ignia, LLC
+| Client        Ignia, LLC
+| Project       Topics Library
+\=============================================================================================================================*/
+using System.ComponentModel.DataAnnotations;
+using OnTopic.Models;
+
+namespace OnTopic.Tests.BindingModels {
+
+  /*============================================================================================================================
+  | BINDING MODEL: RECORD
+  \---------------------------------------------------------------------------------------------------------------------------*/
+  /// <summary>
+  ///   Provides a strongly-typed binding model based on a C# 9.0 <c>record</c> data type to ensure that it can be properly
+  ///   mapped from.
+  /// </summary>
+  /// <remarks>
+  ///   This is a sample class intended for test purposes only; it is not designed for use in a production environment.
+  /// </remarks>
+  public class RecordTopicBindingModel : ITopicBindingModel {
+
+    public RecordTopicBindingModel() { }
+
+    public string? Key { get; init; }
+
+    [Required]
+    public string? ContentType { get; init; }
+
+  } //Class
+} //Namespace

OnTopic.Tests/ReverseTopicMappingServiceTest.cs

@@ -155,6 +155,31 @@ public async Task Map_Existing_ReturnsUpdatedTopic() {
 
     }
 
+    /*==========================================================================================================================
+    | TEST: MAP: RECORD: RETURNS NEW TOPIC
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <summary>
+    ///   Establishes a <see cref="ReverseTopicMappingService"/> and tests mapping a binding model that's based on a C# 9.0
+    ///   record type.
+    /// </summary>
+    [TestMethod]
+    public async Task Map_Record_ReturnsNewTopic() {
+
+      var mappingService        = new ReverseTopicMappingService(_topicRepository);
+
+      var bindingModel          = new RecordTopicBindingModel() {
+        Key                     = "Test",
+        ContentType             = "TextAttributeDescriptor"
+      };
+
+      var target                = await mappingService.MapAsync<TextAttributeDescriptor>(bindingModel).ConfigureAwait(false);
+
+      Assert.IsNotNull(target);
+      Assert.AreEqual<string>("Test", target.Key);
+      Assert.AreEqual<string>("TextAttributeDescriptor", target.ContentType);
+
+    }
+
     /*==========================================================================================================================
     | TEST: MAP: COMPLEX OBJECT: RETURNS FLATTENED TOPIC
     \-------------------------------------------------------------------------------------------------------------------------*/

OnTopic/Mapping/Reverse/BindingModelValidator.cs

@@ -173,6 +173,13 @@ static internal void ValidateProperty(
         return;
       }
 
+      /*------------------------------------------------------------------------------------------------------------------------
+      | Skip properties injected by the compiler for record types
+      \-----------------------------------------------------------------------------------------------------------------------*/
+      if (configuration.Property.Name is "EqualityContract") {
+        return;
+      }
+
       /*------------------------------------------------------------------------------------------------------------------------
       | Handle mapping properties from referenced objects
       \-----------------------------------------------------------------------------------------------------------------------*/

OnTopic/Mapping/Reverse/ReverseTopicMappingService.cs

@@ -275,6 +275,13 @@ private async Task SetPropertyAsync(
         return;
       }
 
+      /*------------------------------------------------------------------------------------------------------------------------
+      | Skip properties injected by the compiler for record types
+      \-----------------------------------------------------------------------------------------------------------------------*/
+      if (configuration.Property.Name is "EqualityContract") {
+        return;
+      }
+
       /*------------------------------------------------------------------------------------------------------------------------
       | Handle mapping properties from referenced objects
       \-----------------------------------------------------------------------------------------------------------------------*/