Fix exception in FieldCount and HasRows. Fixes #728

Author: bgrainger

src/MySqlConnector/MySql.Data.MySqlClient/MySqlDataReader.cs

@@ -170,13 +170,32 @@ private async Task<int> ScanResultSetAsyncAwaited(IOBehavior ioBehavior, ResultS
 
 		public override bool IsDBNull(int ordinal) => GetResultSet().GetCurrentRow().IsDBNull(ordinal);
 
-		public override int FieldCount => GetResultSet().FieldCount;
+		public override int FieldCount
+		{
+			get
+			{
+				VerifyNotDisposed();
+				if (m_resultSet is null)
+					throw new InvalidOperationException("There is no current result set.");
+				return m_resultSet.ContainsCommandParameters ? 0 : m_resultSet.FieldCount;
+			}
+		}
 
 		public override object this[int ordinal] => GetResultSet().GetCurrentRow()[ordinal];
 
 		public override object this[string name] => GetResultSet().GetCurrentRow()[name];
 
-		public override bool HasRows => GetResultSet().HasRows;
+		public override bool HasRows
+		{
+			get
+			{
+				VerifyNotDisposed();
+				if (m_resultSet is null)
+					throw new InvalidOperationException("There is no current result set.");
+				return !m_resultSet.ContainsCommandParameters && m_resultSet.HasRows;
+			}
+		}
+
 		public override bool IsClosed => Command is null;
 		public override int RecordsAffected => m_recordsAffected.GetValueOrDefault(-1);
 

tests/SideBySide/StoredProcedureTests.cs

@@ -130,6 +130,31 @@ public async Task StoredProcedureNoResultSet()
 			Assert.Equal("test value", cmd.Parameters[0].Value);
 		}
 
+		[SkippableFact(Baseline = "https://bugs.mysql.com/bug.php?id=97300")]
+		public async Task FieldCountForNoResultSet()
+		{
+			using var cmd = m_database.Connection.CreateCommand();
+			cmd.CommandText = "out_string";
+			cmd.CommandType = CommandType.StoredProcedure;
+			cmd.Parameters.Add(new MySqlParameter
+			{
+				ParameterName = "@value",
+				DbType = DbType.String,
+				Direction = ParameterDirection.Output,
+			});
+
+			using (var reader = await cmd.ExecuteReaderAsync())
+			{
+				Assert.Equal(0, reader.FieldCount);
+				Assert.False(reader.HasRows);
+				Assert.False(await reader.ReadAsync());
+				Assert.Equal(0, reader.FieldCount);
+				Assert.False(reader.HasRows);
+			}
+
+			Assert.Equal("test value", cmd.Parameters[0].Value);
+		}
+
 #if !NETCOREAPP1_1_2
 		[SkippableFact(Baseline = "https://bugs.mysql.com/bug.php?id=97300")]
 		public async Task GetSchemaTableForNoResultSet()