Remove relationships when calling TopicRepositoryBase.Delete()

JeremyCaney · JeremyCaney · commit 13e4fe9119f8 · 2020-09-08T17:06:15.000-07:00
Previously, when a topic was deleted, relationships from the topic and its descendants were not deleted. This potentially introduces problems as any target relationships outside of the deleted topic graph would maintain `IncomingRelationships` back to the deleted topics. That means that those topics would persist in memory. It also means that any views displaying content from `IncomingRelationships` may provide links to resources that no longer exist. To mitigate this, when `Delete()` is called, it now loops through all topics in the topic graph to be deleted, and removes all relationships from them. And, thanks to a new bug fix which ensures reciprocal `IncomingRelationships` are deleted when `RemoveTopic()` is called (f8b80ec), this fully addresses this issue. In addition, a unit test has been introduced to validate this functionality.
diff --git a/OnTopic.Tests/TopicRepositoryBaseTest.cs b/OnTopic.Tests/TopicRepositoryBaseTest.cs
@@ -146,6 +146,29 @@ public void Delete_NestedTopics_Succeeds() {
 
     }
 
+    /*==========================================================================================================================
+    | TEST: DELETE: RELATIONSHIPS: DELETE RELATIONSHIPS
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <summary>
+    ///   Deletes a topic with outgoing relationships. Deletes those relationships from that topic's <see cref=
+    ///   "Topic.IncomingRelationships"/> collection.
+    /// </summary>
+    [TestMethod]
+    public void Delete_Relationships_DeleteRelationships() {
+
+      var root                  = TopicFactory.Create("Root", "Page");
+      var topic                 = TopicFactory.Create("Topic", "Page", root);
+      var child                 = TopicFactory.Create("Child", "Page", topic);
+      var related               = TopicFactory.Create("Related", "Page", root);
+
+      child.Relationships.SetTopic("Related", related);
+
+      _topicRepository.Delete(topic, true);
+
+      Assert.AreEqual<int>(0, related.IncomingRelationships.GetTopics("Related").Count);
+
+    }
+
     /*==========================================================================================================================
     | TEST: GET ATTRIBUTES: ANY ATTRIBUTES: RETURNS ALL ATTRIBUTES
     \-------------------------------------------------------------------------------------------------------------------------*/
diff --git a/OnTopic/Repositories/TopicRepositoryBase.cs b/OnTopic/Repositories/TopicRepositoryBase.cs
@@ -491,6 +491,21 @@ public virtual void Delete([ValidatedNotNull]Topic topic, bool isRecursive) {
         topic.Parent.Children.Remove(topic.Key);
       }
 
+      /*------------------------------------------------------------------------------------------------------------------------
+      | Remove relationships
+      \-----------------------------------------------------------------------------------------------------------------------*/
+      var descendantTopics      = topic.FindAll(t => true);
+
+      foreach (var descendantTopic in descendantTopics) {
+        foreach (var relationship in descendantTopic.Relationships) {
+          foreach (var relatedTopic in relationship.ToArray()) {
+            if (!descendantTopics.Contains(relatedTopic)) {
+              descendantTopic.Relationships.RemoveTopic(relationship.Name, relatedTopic);
+            }
+          }
+        }
+      }
+
       /*------------------------------------------------------------------------------------------------------------------------
       | If content type, remove from cache
       \-----------------------------------------------------------------------------------------------------------------------*/
