Centralized key navigation properties to INavigableTopicViewModel

JeremyCaney · JeremyCaney · commit adf7ff8b2cb9 · 2021-03-01T12:19:51.000-08:00
These were already defined on `INavigationTopicViewModel&lt;T&gt;`, but that _also_ implemented `IHierarchicalTopicViewModel&lt;T&gt;`.

Sometimes, there are topics that should be evaluated for navigation, but which _aren't_ hierarchical, and which _don't_ necessitate the use of e.g. the `IHierarchicalTopicMappingService` or `NavigationViewComponentBase&lt;T&gt;`. For example, offering a list of child topics on a page. In this case, these _may_ implement `IHierarchicalTopicViewModel&lt;T&gt;`, but they only _need_ `Title`, `ShortTitle`, and `WebPath`.

To support this, the `INavigableTopicViewModel` extracts these from the `INavigationTopicViewModel&lt;T&gt;` so they can, optionally, be applied independently. Then, the `INavigationTopicViewModel&lt;T&gt;` effectively becomes a composite of `INavigableTopicViewModel` and `IHierarchicalTopicViewModel&lt;T&gt;`, adding only `IsSelected()`.

This is useful since the view models for the `NavigationTopicViewComponent&lt;T&gt;` are likely going to be independent from other view models, since most view models don't want or need a `Children` collection. But many basic view models will satisfy the `INavigableTopicViewModel` interface, and should be usable for that purpose. This allows different view models types from different chains (e.g., `OnTopic.ViewModels` and a separate customer implementation) to be handled by e.g. the same partial control.
diff --git a/OnTopic/Models/INavigableTopicViewModel.cs b/OnTopic/Models/INavigableTopicViewModel.cs
@@ -0,0 +1,47 @@
+﻿/*==============================================================================================================================
+| Author        Ignia, LLC
+| Client        Ignia
+| Project       Website
+\=============================================================================================================================*/
+using System.ComponentModel.DataAnnotations;
+using System.Diagnostics.CodeAnalysis;
+
+namespace OnTopic.Models {
+
+  /*============================================================================================================================
+  | INTERFACE: NAVIGABLE TOPIC VIEW MODEL
+  \---------------------------------------------------------------------------------------------------------------------------*/
+  /// <summary>
+  ///   Ensures basic properties needed to treat a view model as a navigable entry.
+  /// </summary>
+  /// <remarks>
+  ///   No topics are expected to have a <c>Navigable</c> content type. Instead, implementers of this view model are expected
+  ///   to manually construct instances.
+  /// </remarks>
+  public interface INavigableTopicViewModel {
+
+    /*==========================================================================================================================
+    | PROPERTY: TITLE
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <inheritdoc cref="ITopicViewModel.Title"/>
+    [Required, NotNull, DisallowNull]
+    string? Title { get; init; }
+
+    /*==========================================================================================================================
+    | PROPERTY: SHORT TITLE
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <summary>
+    ///   In addition to the Title, a site may opt to define a Short Title used exclusively in the navigation. If present, this
+    ///   value should be used instead of Title.
+    /// </summary>
+    string? ShortTitle { get; init; }
+
+    /*==========================================================================================================================
+    | PROPERTY: WEB PATH
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <inheritdoc cref="ITopicViewModel.WebPath"/>
+    [Required, NotNull, DisallowNull]
+    string? WebPath { get; init; }
+
+  } //Class
+} //Namespace
diff --git a/OnTopic/Models/INavigationTopicViewModel{T}.cs b/OnTopic/Models/INavigationTopicViewModel{T}.cs
@@ -16,28 +16,10 @@ namespace OnTopic.Models {
   ///   No topics are expected to have a <c>Navigation</c> content type. Instead, implementers of this view model are expected
   ///   to manually construct instances.
   /// </remarks>
-  public interface INavigationTopicViewModel<T> : IHierarchicalTopicViewModel<T> where T: INavigationTopicViewModel<T> {
-
-    /*==========================================================================================================================
-    | PROPERTY: TITLE
-    \-------------------------------------------------------------------------------------------------------------------------*/
-    /// <inheritdoc cref="ITopicViewModel.Title"/>
-    string? Title { get; init; }
-
-    /*==========================================================================================================================
-    | PROPERTY: SHORT TITLE
-    \-------------------------------------------------------------------------------------------------------------------------*/
-    /// <summary>
-    ///   In addition to the Title, a site may opt to define a Short Title used exclusively in the navigation. If present, this
-    ///   value should be used instead of Title.
-    /// </summary>
-    string? ShortTitle { get; init; }
-
-    /*==========================================================================================================================
-    | PROPERTY: WEB PATH
-    \-------------------------------------------------------------------------------------------------------------------------*/
-    /// <inheritdoc cref="ITopicViewModel.WebPath"/>
-    string? WebPath { get; init; }
+  public interface INavigationTopicViewModel<T> :
+    INavigableTopicViewModel,
+    IHierarchicalTopicViewModel<T> where T: INavigationTopicViewModel<T>
+  {
 
     /*==========================================================================================================================
     | METHOD: IS SELECTED?
