Migrated to C# 8's new inline using syntax

With C# 8, we no longer need to nest `IDisposable`s inside a `using {}` block or manually call `Dispose()` as part of e.g. a `finally {}` block. Instead, by prefixing the `IDisposable`'s declaration with `using`, they will automatically be disposed of when the code execution exits the current block. This allows us to entirely remove all of the `finally {}` blocks.

Because `using var variable` doesn't align neatly with `var variable`, I've added a line break between the declaration of `using var` and `var` blocks. I'm not sure if this is a best practice yet—it's a gap in our style guide for now—but I _think_ it's a preference. We'll keep evaluating this as we implement the pattern more frequently.

Author: JeremyCaney

OnTopic.Data.Sql/SqlTopicRepository.cs

@@ -79,8 +79,9 @@ public override Topic Load(string? topicKey = null, bool isRecursive = true) {
       /*------------------------------------------------------------------------------------------------------------------------
       | Establish database connection
       \-----------------------------------------------------------------------------------------------------------------------*/
-      var connection            = new SqlConnection(_connectionString);
-      var command               = new SqlCommand("GetTopicID", connection);
+      using var connection      = new SqlConnection(_connectionString);
+      using var command         = new SqlCommand("GetTopicID", connection);
+
       var topicId               = -1;
 
       command.CommandType       = CommandType.StoredProcedure;
@@ -110,14 +111,6 @@ public override Topic Load(string? topicKey = null, bool isRecursive = true) {
         throw new TopicRepositoryException($"Topic(s) failed to load: '{exception.Message}'", exception);
       }
 
-      /*------------------------------------------------------------------------------------------------------------------------
-      | Close connection
-      \-----------------------------------------------------------------------------------------------------------------------*/
-      finally {
-        command?.Dispose();
-        connection.Close();
-      }
-
       /*------------------------------------------------------------------------------------------------------------------------
       | Validate results
       \-----------------------------------------------------------------------------------------------------------------------*/
@@ -139,12 +132,12 @@ public override Topic Load(int topicId, bool isRecursive = true) {
       | Establish database connection
       \-----------------------------------------------------------------------------------------------------------------------*/
       var topic                 = (Topic?)null;
-      var connection            = new SqlConnection(_connectionString);
-      var command               = new SqlCommand("GetTopics", connection) {
+
+      using var connection      = new SqlConnection(_connectionString);
+      using var command         = new SqlCommand("GetTopics", connection) {
         CommandType             = CommandType.StoredProcedure,
         CommandTimeout          = 120
       };
-      var reader                = (SqlDataReader?)null;
 
       /*------------------------------------------------------------------------------------------------------------------------
       | Establish query parameters
@@ -157,7 +150,7 @@ public override Topic Load(int topicId, bool isRecursive = true) {
       \-----------------------------------------------------------------------------------------------------------------------*/
       try {
         connection.Open();
-        reader                  = command.ExecuteReader();
+        using var reader        = command.ExecuteReader();
         topic                   = reader.LoadTopicGraph();
       }
 
@@ -168,15 +161,6 @@ public override Topic Load(int topicId, bool isRecursive = true) {
         throw new TopicRepositoryException($"Topics failed to load: '{exception.Message}'", exception);
       }
 
-      /*------------------------------------------------------------------------------------------------------------------------
-      | Close connection
-      \-----------------------------------------------------------------------------------------------------------------------*/
-      finally {
-        reader?.Dispose();
-        command?.Dispose();
-        connection.Close();
-      }
-
       /*------------------------------------------------------------------------------------------------------------------------
       | Validate results
       \-----------------------------------------------------------------------------------------------------------------------*/
@@ -212,12 +196,12 @@ public override Topic Load(int topicId, DateTime version) {
       | Establish database connection
       \-----------------------------------------------------------------------------------------------------------------------*/
       var topic                 = (Topic?)null;
-      var connection            = new SqlConnection(_connectionString);
-      var command               = new SqlCommand("GetTopicVersion", connection) {
+
+      using var connection      = new SqlConnection(_connectionString);
+      using var command         = new SqlCommand("GetTopicVersion", connection) {
         CommandType             = CommandType.StoredProcedure,
         CommandTimeout          = 120
       };
-      var reader                = (SqlDataReader?)null;
 
       command.CommandType       = CommandType.StoredProcedure;
 
@@ -232,7 +216,7 @@ public override Topic Load(int topicId, DateTime version) {
       \-----------------------------------------------------------------------------------------------------------------------*/
       try {
         connection.Open();
-        reader                  = command.ExecuteReader();
+        using var reader        = command.ExecuteReader();
         topic                   = reader.LoadTopicGraph(false);
       }
 
@@ -243,15 +227,6 @@ public override Topic Load(int topicId, DateTime version) {
         throw new TopicRepositoryException($"Topics failed to load: '{exception.Message}'", exception);
       }
 
-      /*------------------------------------------------------------------------------------------------------------------------
-      | Close connection
-      \-----------------------------------------------------------------------------------------------------------------------*/
-      finally {
-        reader?.Dispose();
-        command?.Dispose();
-        connection.Close();
-      }
-
       /*------------------------------------------------------------------------------------------------------------------------
       | Return objects
       \-----------------------------------------------------------------------------------------------------------------------*/
@@ -270,7 +245,8 @@ public override int Save([NotNull]Topic topic, bool isRecursive = false, bool is
       \-----------------------------------------------------------------------------------------------------------------------*/
       var version               = new SqlDateTime(DateTime.Now);
       var unresolvedTopics      = new List<Topic>();
-      var connection            = new SqlConnection(_connectionString);
+
+      using var connection      = new SqlConnection(_connectionString);
 
       connection.Open();
 
@@ -290,7 +266,6 @@ public override int Save([NotNull]Topic topic, bool isRecursive = false, bool is
       | Return value
       \-----------------------------------------------------------------------------------------------------------------------*/
       connection.Close();
-      connection.Dispose();
       return topicId;
 
     }
@@ -373,7 +348,7 @@ SqlDateTime version
       /*------------------------------------------------------------------------------------------------------------------------
       | Add indexed attributes that are dirty
       \-----------------------------------------------------------------------------------------------------------------------*/
-      var attributeValues       = new AttributeValuesDataTable();
+      using var attributeValues = new AttributeValuesDataTable();
 
       foreach (var attributeValue in indexedAttributeList) {
         attributeValues.AddRow(attributeValue.Key, attributeValue.Value);
@@ -418,7 +393,8 @@ SqlDateTime version
       | Establish database connection
       \-----------------------------------------------------------------------------------------------------------------------*/
       var procedureName         = !topic.IsSaved? "CreateTopic" : "UpdateTopic";
-      var command               = new SqlCommand(procedureName, connection) {
+
+      using var command         = new SqlCommand(procedureName, connection) {
         CommandType             = CommandType.StoredProcedure
       };
 
@@ -477,21 +453,12 @@ SqlDateTime version
       | Catch exception
       \-----------------------------------------------------------------------------------------------------------------------*/
       catch (SqlException exception) {
-        connection?.Dispose();
         throw new TopicRepositoryException(
           $"Failed to save Topic '{topic.Key}' ({topic.Id}) via '{_connectionString}': '{exception.Message}'",
           exception
         );
       }
 
-      /*------------------------------------------------------------------------------------------------------------------------
-      | Close connection
-      \-----------------------------------------------------------------------------------------------------------------------*/
-      finally {
-        command?.Dispose();
-        attributeValues.Dispose();
-      }
-
       /*------------------------------------------------------------------------------------------------------------------------
       | Return value
       \-----------------------------------------------------------------------------------------------------------------------*/
@@ -526,8 +493,8 @@ public override void Move(Topic topic, Topic target, Topic? sibling) {
       /*------------------------------------------------------------------------------------------------------------------------
       | Establish database connection
       \-----------------------------------------------------------------------------------------------------------------------*/
-      var connection            = new SqlConnection(_connectionString);
-      var command               = new SqlCommand("MoveTopic", connection) {
+      using var connection      = new SqlConnection(_connectionString);
+      using var command         = new SqlCommand("MoveTopic", connection) {
         CommandType             = CommandType.StoredProcedure
       };
 
@@ -560,14 +527,6 @@ public override void Move(Topic topic, Topic target, Topic? sibling) {
         );
       }
 
-      /*------------------------------------------------------------------------------------------------------------------------
-      | Close connection
-      \-----------------------------------------------------------------------------------------------------------------------*/
-      finally {
-        command?.Dispose();
-        connection.Dispose();
-      }
-
       /*------------------------------------------------------------------------------------------------------------------------
       | Reset dirty status
       \-----------------------------------------------------------------------------------------------------------------------*/
@@ -589,8 +548,8 @@ public override void Delete(Topic topic, bool isRecursive = false) {
       /*------------------------------------------------------------------------------------------------------------------------
       | Delete from database
       \-----------------------------------------------------------------------------------------------------------------------*/
-      var connection            = new SqlConnection(_connectionString);
-      var command               = new SqlCommand("DeleteTopic", connection) {
+      using var connection      = new SqlConnection(_connectionString);
+      using var command         = new SqlCommand("DeleteTopic", connection) {
         CommandType             = CommandType.StoredProcedure
       };
 
@@ -617,14 +576,6 @@ public override void Delete(Topic topic, bool isRecursive = false) {
         );
       }
 
-      /*------------------------------------------------------------------------------------------------------------------------
-      | Close connection
-      \-----------------------------------------------------------------------------------------------------------------------*/
-      finally {
-        command?.Dispose();
-        connection?.Dispose();
-      }
-
     }
 
     /*==========================================================================================================================
@@ -644,7 +595,6 @@ private static void PersistRelations(Topic topic, SqlConnection connection) {
       if (!topic.Relationships.Keys.Any()) {
         return;
       }
-      var command               = (SqlCommand?)null;
 
       try {
 
@@ -653,12 +603,12 @@ private static void PersistRelations(Topic topic, SqlConnection connection) {
         \---------------------------------------------------------------------------------------------------------------------*/
         foreach (var key in topic.Relationships.Keys) {
 
-          var targetIds         = new TopicListDataTable();
           var relatedTopics     = topic.Relationships.GetTopics(key);
           var topicId           = topic.Id.ToString(CultureInfo.InvariantCulture);
           var savedTopics       = relatedTopics.Where(t => t.IsSaved).Select<Topic, int>(m => m.Id);
 
-          command               = new SqlCommand("UpdateRelationships", connection) {
+          using var targetIds   = new TopicListDataTable();
+          using var command     = new SqlCommand("UpdateRelationships", connection) {
             CommandType         = CommandType.StoredProcedure
           };
 
@@ -673,8 +623,6 @@ private static void PersistRelations(Topic topic, SqlConnection connection) {
 
           command.ExecuteNonQuery();
 
-          targetIds.Dispose();
-
           //Reset isDirty, assuming there aren't any unresolved references
           relatedTopics.IsDirty = savedTopics.Count() < relatedTopics.Count;
 
@@ -692,14 +640,6 @@ private static void PersistRelations(Topic topic, SqlConnection connection) {
         );
       }
 
-      /*------------------------------------------------------------------------------------------------------------------------
-      | Close connection
-      \-----------------------------------------------------------------------------------------------------------------------*/
-      finally {
-        command?.Dispose();
-        //Since the SQL connection is being passed in, do not close connection; this allows connection pooling.
-      }
-
       /*------------------------------------------------------------------------------------------------------------------------
       | Return
       \-----------------------------------------------------------------------------------------------------------------------*/