Fix conversion of LastInsertedId. Fixes #422

The OK payload contains an unsigned 64-bit integer (for the last insert ID), which needs to be returned as a 64-bit signed integer (in the C# API). The client needs to determine how to interpret it, based on the signedness of the ID column.

Author: bgrainger

src/MySqlConnector/Core/ResultSet.cs

@@ -47,7 +47,7 @@ public async Task<ResultSet> ReadResultSetHeaderAsync(IOBehavior ioBehavior)
 					{
 						var ok = OkPayload.Create(payload);
 						RecordsAffected = (RecordsAffected ?? 0) + ok.AffectedRowCount;
-						LastInsertId = ok.LastInsertId;
+						LastInsertId = unchecked((long) ok.LastInsertId);
 						if (ok.NewSchema != null)
 							Connection.Session.DatabaseOverride = ok.NewSchema;
 						ColumnDefinitions = null;

src/MySqlConnector/Protocol/Payloads/OkPayload.cs

@@ -8,7 +8,7 @@ namespace MySqlConnector.Protocol.Payloads
 	internal sealed class OkPayload
 	{
 		public int AffectedRowCount { get; }
-		public long LastInsertId { get; }
+		public ulong LastInsertId { get; }
 		public ServerStatus ServerStatus { get; }
 		public int WarningCount { get; }
 		public string NewSchema { get; }
@@ -34,7 +34,7 @@ public static OkPayload Create(PayloadData payload, bool deprecateEof)
 			if (signature != Signature && (!deprecateEof || signature != EofPayload.Signature))
 				throw new FormatException("Expected to read 0x00 or 0xFE but got 0x{0:X2}".FormatInvariant(signature));
 			var affectedRowCount = checked((int) reader.ReadLengthEncodedInteger());
-			var lastInsertId = checked((long) reader.ReadLengthEncodedInteger());
+			var lastInsertId = reader.ReadLengthEncodedInteger();
 			var serverStatus = (ServerStatus) reader.ReadUInt16();
 			var warningCount = (int) reader.ReadUInt16();
 			string newSchema = null;
@@ -71,7 +71,7 @@ public static OkPayload Create(PayloadData payload, bool deprecateEof)
 			return new OkPayload(affectedRowCount, lastInsertId, serverStatus, warningCount, newSchema);
 		}
 
-		private OkPayload(int affectedRowCount, long lastInsertId, ServerStatus serverStatus, int warningCount, string newSchema)
+		private OkPayload(int affectedRowCount, ulong lastInsertId, ServerStatus serverStatus, int warningCount, string newSchema)
 		{
 			AffectedRowCount = affectedRowCount;
 			LastInsertId = lastInsertId;

tests/SideBySide/InsertTests.cs

@@ -36,6 +36,48 @@ public async Task LastInsertedId()
 			}
 		}
 
+		[Fact]
+		public async Task LastInsertedIdNegative()
+		{
+			await m_database.Connection.ExecuteAsync(@"drop table if exists insert_ai;
+create table insert_ai(rowid integer not null primary key auto_increment);");
+			try
+			{
+				await m_database.Connection.OpenAsync();
+				using (var command = new MySqlCommand("INSERT INTO insert_ai(rowid) VALUES (@rowid);", m_database.Connection))
+				{
+					command.Parameters.AddWithValue("@rowid", -1);
+					await command.ExecuteNonQueryAsync();
+					Assert.Equal(-1L, command.LastInsertedId);
+				}
+			}
+			finally
+			{
+				m_database.Connection.Close();
+			}
+		}
+
+		[Fact]
+		public async Task LastInsertedIdUlong()
+		{
+			await m_database.Connection.ExecuteAsync(@"drop table if exists insert_ai;
+create table insert_ai(rowid bigint unsigned not null primary key auto_increment);");
+			try
+			{
+				await m_database.Connection.OpenAsync();
+				using (var command = new MySqlCommand("INSERT INTO insert_ai(rowid) VALUES (@rowid);", m_database.Connection))
+				{
+					command.Parameters.AddWithValue("@rowid", ((ulong) long.MaxValue) + 1);
+					await command.ExecuteNonQueryAsync();
+					Assert.Equal(long.MinValue, command.LastInsertedId);
+				}
+			}
+			finally
+			{
+				m_database.Connection.Close();
+			}
+		}
+
 		[Fact]
 		public async Task RowsAffected()
 		{