Throw InvalidCastException from GetGuid if value is null.

Author: bgrainger

src/MySqlConnector/Core/Row.cs

@@ -91,8 +91,8 @@ public long GetBytes(int ordinal, long dataOffset, byte[] buffer, int bufferOffs
 			var column = ResultSet.ColumnDefinitions[ordinal];
 			var columnType = column.ColumnType;
 			if ((column.ColumnFlags & ColumnFlags.Binary) == 0 ||
-			    (columnType != ColumnType.String && columnType != ColumnType.VarString && columnType != ColumnType.TinyBlob &&
-			     columnType != ColumnType.Blob && columnType != ColumnType.MediumBlob && columnType != ColumnType.LongBlob))
+				(columnType != ColumnType.String && columnType != ColumnType.VarString && columnType != ColumnType.TinyBlob &&
+				columnType != ColumnType.Blob && columnType != ColumnType.MediumBlob && columnType != ColumnType.LongBlob))
 			{
 				throw new InvalidCastException("Can't convert {0} to bytes.".FormatInvariant(columnType));
 			}
@@ -128,12 +128,14 @@ public Guid GetGuid(int ordinal)
 			if (value is byte[] bytes && bytes.Length == 16)
 				return new Guid(bytes);
 
+			if (m_dataOffsets[ordinal] == -1)
+				throw new InvalidCastException("Column is NULL.");
 			throw new MySqlException("The value could not be converted to a GUID: {0}".FormatInvariant(value));
 		}
 
 		public short GetInt16(int ordinal)
 		{
-			object value = GetValue(ordinal);
+			var value = GetValue(ordinal);
 			if (value is short)
 				return (short) value;
 
@@ -158,7 +160,7 @@ public short GetInt16(int ordinal)
 
 		public int GetInt32(int ordinal)
 		{
-			object value = GetValue(ordinal);
+			var value = GetValue(ordinal);
 			if (value is int)
 				return (int) value;
 
@@ -183,7 +185,7 @@ public int GetInt32(int ordinal)
 
 		public long GetInt64(int ordinal)
 		{
-			object value = GetValue(ordinal);
+			var value = GetValue(ordinal);
 			if (value is long)
 				return (long) value;
 
@@ -216,7 +218,7 @@ public long GetInt64(int ordinal)
 
 		public double GetDouble(int ordinal)
 		{
-			object value = GetValue(ordinal);
+			var value = GetValue(ordinal);
 			return value is float floatValue ? floatValue : (double) value;
 		}
 

tests/SideBySide/DataTypes.cs

@@ -14,8 +14,10 @@
 // Additionally, that is what DbDataReader.GetFieldValue<T> throws. For consistency, we prefer InvalidCastException.
 #if BASELINE
 using GetValueWhenNullException = System.Data.SqlTypes.SqlNullValueException;
+using GetGuidWhenNullException = MySql.Data.MySqlClient.MySqlException;
 #else
 using GetValueWhenNullException = System.InvalidCastException;
+using GetGuidWhenNullException = System.InvalidCastException;
 #endif
 
 namespace SideBySide
@@ -286,7 +288,7 @@ public void QueryGuid(string column, string dataTypeName, object[] expected)
 			for (int i = 0; i < expected.Length; i++)
 				if (expected[i] != null)
 					expected[i] = Guid.Parse((string) expected[i]);
-			DoQuery<MySqlException>("strings", column, dataTypeName, expected, reader => reader.GetGuid(0));
+			DoQuery<GetGuidWhenNullException>("strings", column, dataTypeName, expected, reader => reader.GetGuid(0));
 		}
 
 		[Theory]
@@ -379,7 +381,7 @@ public async Task GetGuid(string column, Type fieldType)
 
 					Assert.True(await reader.ReadAsync().ConfigureAwait(false));
 					Assert.True(reader.IsDBNull(0));
-					Assert.Throws<MySqlException>(() => reader.GetGuid(0));
+					Assert.Throws<GetGuidWhenNullException>(() => reader.GetGuid(0));
 
 					Assert.True(await reader.ReadAsync().ConfigureAwait(false));
 					Assert.False(reader.IsDBNull(0));