Replace large switch statement with lookup table.

Author: bgrainger

src/MySqlConnector/MySqlClient/MySqlConnection.cs

@@ -257,7 +257,7 @@ public override System.Data.DataTable GetSchema(string collectionName, string[]
 					var dbType = dbTypeMap.DbTypes.FirstOrDefault();
 					dt.Rows.Add(new object[] {
 							dbTypeMap.ClrType.FullName,
-							map.ColumnTypeName,
+							map.DataTypeName,
 							(int)dbType,
 							map.Unsigned
 						});

src/MySqlConnector/MySqlClient/Results/ResultSet.cs

@@ -275,97 +275,10 @@ public string GetDataTypeName(int ordinal)
 			if (ordinal < 0 || ordinal > ColumnDefinitions.Length)
 				throw new ArgumentOutOfRangeException(nameof(ordinal), "value must be between 0 and {0}.".FormatInvariant(ColumnDefinitions.Length));
 
-			switch (ColumnTypes[ordinal])
-			{
-			case MySqlDbType.Bool:
-				return "BOOL";
-
-			case MySqlDbType.UByte:
-			case MySqlDbType.Byte:
-				return "TINYINT";
-
-			case MySqlDbType.UInt16:
-			case MySqlDbType.Int16:
-				return "SMALLINT";
-
-			case MySqlDbType.UInt24:
-			case MySqlDbType.Int24:
-				return "MEDIUMINT";
-
-			case MySqlDbType.UInt32:
-			case MySqlDbType.Int32:
-				return "INT";
-
-			case MySqlDbType.UInt64:
-			case MySqlDbType.Int64:
-				return "BIGINT";
-
-			case MySqlDbType.Bit:
-				return "BIT";
-
-			case MySqlDbType.Enum:
-				return "ENUM";
-
-			case MySqlDbType.Set:
-				return "SET";
-
-			case MySqlDbType.Guid:
-				return "CHAR(36)";
-
-			case MySqlDbType.String:
-				var columnDefinition = ColumnDefinitions[ordinal];
-				return string.Format(CultureInfo.InvariantCulture, "CHAR({0})", columnDefinition.ColumnLength / SerializationUtility.GetBytesPerCharacter(columnDefinition.CharacterSet));
-
-			case MySqlDbType.VarString:
-			case MySqlDbType.TinyText:
-			case MySqlDbType.Text:
-			case MySqlDbType.MediumText:
-			case MySqlDbType.LongText:
-				return "VARCHAR";
-
-			case MySqlDbType.Binary:
-			case MySqlDbType.VarBinary:
-			case MySqlDbType.TinyBlob:
-			case MySqlDbType.Blob:
-			case MySqlDbType.MediumBlob:
-			case MySqlDbType.LongBlob:
-				return "BLOB";
-
-			case MySqlDbType.Date:
-				return "DATE";
-
-			case MySqlDbType.DateTime:
-				return "DATETIME";
-
-			case MySqlDbType.Timestamp:
-				return "TIMESTAMP";
-
-			case MySqlDbType.Time:
-				return "TIME";
-
-			case MySqlDbType.Year:
-				return "YEAR";
-
-			case MySqlDbType.Float:
-				return "FLOAT";
-
-			case MySqlDbType.Double:
-				return "DOUBLE";
-
-			case MySqlDbType.Decimal:
-			case MySqlDbType.NewDecimal:
-				return "DECIMAL";
-
-			case MySqlDbType.JSON:
-				return "JSON";
-
-			case MySqlDbType.Null:
-				// not a valid data type name, but only happens when there is no way to infer the type of the column, e.g., "SELECT NULL;"
-				return "NULL";
-
-			default:
-				throw new NotImplementedException("GetDataTypeName for {0} is not implemented".FormatInvariant(ColumnTypes[ordinal]));
-			}
+			var mySqlDbType = ColumnTypes[ordinal];
+			if (mySqlDbType == MySqlDbType.String)
+				return string.Format(CultureInfo.InvariantCulture, "CHAR({0})", ColumnDefinitions[ordinal].ColumnLength / SerializationUtility.GetBytesPerCharacter(ColumnDefinitions[ordinal].CharacterSet));
+			return TypeMapper.Mapper.GetColumnMapping(mySqlDbType).SimpleDataTypeName;
 		}
 
 		public Type GetFieldType(int ordinal)

src/MySqlConnector/MySqlClient/Types/ColumnTypeMapping.cs

@@ -1,37 +1,28 @@
-using System.Collections.Generic;
-using MySql.Data.Serialization;
-
 namespace MySql.Data.MySqlClient.Types
 {
-	internal class ColumnTypeMapping
+	internal sealed class ColumnTypeMapping
 	{
-		internal static string CreateLookupKey(string columnTypeName, bool unsigned, int length)
-		{
-			return columnTypeName.Trim().ToLowerInvariant()
-			       + "|" + (unsigned ? "u" : "s")
-			       + "|" + length;
-		}
+		public static string CreateLookupKey(string columnTypeName, bool isUnsigned, int length) => $"{columnTypeName}|{(isUnsigned ? "u" : "s")}|{length}";
 
-		public ColumnTypeMapping(string columnTypeName, DbTypeMapping dbTypeMapping, IEnumerable<ColumnType> columnTypes,
-			bool unsigned=false,
-			bool binary=false,
-			int length=0
-		)
+		public ColumnTypeMapping(string dataTypeName, DbTypeMapping dbTypeMapping, MySqlDbType mySqlDbType, bool unsigned = false, bool binary = false, int length = 0, string simpleDataTypeName = null)
 		{
-			ColumnTypeName = columnTypeName;
+			DataTypeName = dataTypeName;
+			SimpleDataTypeName = simpleDataTypeName ?? dataTypeName;
 			DbTypeMapping = dbTypeMapping;
+			MySqlDbType = mySqlDbType;
 			Unsigned = unsigned;
 			Binary = binary;
 			Length = length;
 		}
 
-		internal readonly string ColumnTypeName;
-		internal readonly DbTypeMapping DbTypeMapping;
-		internal readonly IEnumerable<ColumnType> ColumnTypes;
-		internal readonly bool Binary;
-		internal readonly bool Unsigned;
-		internal readonly int Length;
+		public string DataTypeName { get; }
+		public string SimpleDataTypeName { get; }
+		public DbTypeMapping DbTypeMapping { get; }
+		public MySqlDbType MySqlDbType { get; }
+		public bool Binary { get; }
+		public bool Unsigned { get; }
+		public int Length { get; }
 
-		internal string LookupKey => CreateLookupKey(ColumnTypeName, Unsigned, Length);
+		public string CreateLookupKey() => CreateLookupKey(DataTypeName, Unsigned, Length);
 	}
-}
+}