Implement the new TopicListDataTable class

In a previous commit (7a37dc9) we introduced a new `TopicListDataTable` which centralizes the definition of the `TopicList` table-valued type in the SQL Server database schema. In this commit, I implement that in the `SqlTopicRepository`, simplifying the code for `PersistRelations()`.

As part of this, I moved the construction of the data table into the `for` loop so that we don't need to `Clear()` it each iteration. Not sure where this nets out in terms of performance, but it makes for cleaner and more intuitive code.

Author: JeremyCaney

OnTopic.Data.Sql/SqlTopicRepository.cs

@@ -657,11 +657,6 @@ private static string PersistRelations(Topic topic, SqlConnection connection, bo
         return "";
       }
       var command               = (SqlCommand?)null;
-      var targetIds             = new DataTable();
-
-      targetIds.Columns.Add(
-        new DataColumn("TopicID", typeof(int))
-      );
 
       try {
 
@@ -670,6 +665,7 @@ private static string PersistRelations(Topic topic, SqlConnection connection, bo
         \---------------------------------------------------------------------------------------------------------------------*/
         foreach (var key in topic.Relationships.Keys) {
 
+          var targetIds         = new TopicListDataTable();
           var scope             = topic.Relationships.GetTopics(key);
           var topicId           = topic.Id.ToString(CultureInfo.InvariantCulture);
           var relatedTopics     = scope.Where(t => t.Id > 0).Select<Topic, int>(m => m.Id);
@@ -679,9 +675,7 @@ private static string PersistRelations(Topic topic, SqlConnection connection, bo
           };
 
           foreach (var targetTopicId in relatedTopics) {
-            var record          = targetIds.NewRow();
-            record["TopicID"]   = targetTopicId;
-            targetIds.Rows.Add(record);
+            targetIds.AddRow(targetTopicId);
           }
 
           // Add Parameters
@@ -691,8 +685,9 @@ private static string PersistRelations(Topic topic, SqlConnection connection, bo
 
           command.ExecuteNonQuery();
 
-          // Clear rows
-          targetIds.Clear();
+          targetIds.Dispose();
+
+          //Reset isDirty, assuming there aren't any unresolved references
           scope.IsDirty = relatedTopics.Count() < scope.Count;
 
         }
@@ -714,7 +709,6 @@ private static string PersistRelations(Topic topic, SqlConnection connection, bo
       \-----------------------------------------------------------------------------------------------------------------------*/
       finally {
         command?.Dispose();
-        targetIds.Dispose();
         //Since the SQL connection is being passed in, do not close connection; this allows connection pooling.
       }