Fix HasRows returning false. Fixes #327

Author: bgrainger

src/MySqlConnector/MySqlClient/Results/ResultSet.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
@@ -29,6 +29,7 @@ public async Task<ResultSet> ReadResultSetHeaderAsync(IOBehavior ioBehavior)
 			m_readBuffer.Clear();
 			m_row = null;
 			m_rowBuffered = null;
+			m_hasRows = false;
 
 			try
 			{
@@ -226,6 +227,7 @@ Row ScanRowAsyncRemainder(PayloadData payload)
 					row = new Row(this);
 				row.SetData(m_dataLengths, m_dataOffsets, payload.ArraySegment);
 				m_rowBuffered = row;
+				m_hasRows = true;
 				return row;
 			}
 		}
@@ -395,7 +397,7 @@ public bool HasRows
 			{
 				if (BufferState == ResultSetState.ReadResultSetHeader)
 					return BufferReadAsync(IOBehavior.Synchronous, CancellationToken.None).GetAwaiter().GetResult() != null;
-				return BufferState == ResultSetState.ReadingRows;
+				return m_hasRows;
 			}
 		}
 
@@ -423,5 +425,6 @@ public Row GetCurrentRow()
 		readonly Queue<Row> m_readBuffer = new Queue<Row>();
 		Row m_row;
 		Row m_rowBuffered;
+		bool m_hasRows;
 	}
 }

tests/SideBySide/QueryTests.cs

@@ -795,6 +795,41 @@ public void ReturnDerivedTypes()
 			}
 		}
 
+		[Theory]
+		[InlineData(new[] { 1 }, new[] { true })]
+		[InlineData(new[] { 4 }, new[] { false })]
+		[InlineData(new[] { 1, 2 }, new[] { true, true })]
+		[InlineData(new[] { 1, 4 }, new[] { true, false })]
+		[InlineData(new[] { 4, 1 }, new[] { false, true })]
+		[InlineData(new[] { 4, 5 }, new[] { false, false })]
+		public void HasRows(int[] values, bool[] expecteds)
+		{
+			m_database.Connection.Execute(@"drop table if exists has_rows;
+create table has_rows(value int not null);
+insert into has_rows(value) values(1),(2),(3);");
+
+			var sql = "";
+			foreach (var value in values)
+				sql += $"select * from has_rows where value = {value};";
+
+			using (var cmd = m_database.Connection.CreateCommand())
+			{
+				cmd.CommandText = sql;
+				using (var reader = cmd.ExecuteReader())
+				{
+					for (int i = 0; i < expecteds.Length; i++)
+					{
+						Assert.Equal(expecteds[i], reader.HasRows);
+						Assert.Equal(expecteds[i], reader.Read());
+						Assert.False(reader.Read());
+						Assert.Equal(expecteds[i], reader.HasRows);
+
+						Assert.Equal(i != expecteds.Length - 1, reader.NextResult());
+					}
+				}
+			}
+		}
+
 		class BoolTest
 		{
 			public int Id { get; set; }