Add decimal and guid reading support

Author: Giorgi

DuckDB.NET.Bindings/DuckDBWrapperObjects.cs

@@ -137,17 +137,24 @@ public T GetValue<T>()
 
             DuckDBType.Float => Cast(NativeMethods.Value.DuckDBGetFloat(this)),
             DuckDBType.Double => Cast(NativeMethods.Value.DuckDBGetDouble(this)),
-
+            
+            DuckDBType.Decimal => Cast(decimal.Parse(NativeMethods.Value.DuckDBGetVarchar(this))),
+            DuckDBType.Uuid => Cast(new Guid(NativeMethods.Value.DuckDBGetVarchar(this))),
+            
+            //DuckDBType.HugeInt => expr,
+            //DuckDBType.UnsignedHugeInt => expr,
+            
             DuckDBType.Varchar => Cast(NativeMethods.Value.DuckDBGetVarchar(this)),
+            
+            //DuckDBType.Date => expr,
+            //DuckDBType.Time => expr,
+            //DuckDBType.TimeTz => expr,
+            //DuckDBType.Interval => expr,
             DuckDBType.Timestamp => Cast(NativeMethods.DateTimeHelpers.DuckDBFromTimestamp(NativeMethods.Value.DuckDBGetTimestamp(this)).ToDateTime()),
-            //DuckDBType.Decimal => Cast(decimal.Parse(NativeMethods.Value.DuckDBGetVarchar(this))),
-            //DuckDBType.Uuid => Cast(new Guid(NativeMethods.Value.DuckDBGetVarchar(this))),
             //DuckDBType.TimestampS => expr,
             //DuckDBType.TimestampMs => expr,
             //DuckDBType.TimestampNs => expr,
-            //DuckDBType.TimeTz => expr,
             //DuckDBType.TimestampTz => expr,
-
             _ => throw new NotImplementedException($"Cannot read value of type {typeof(T).FullName}")
         };
 

DuckDB.NET.Bindings/NativeMethods/NativeMethods.LogicalType.cs

@@ -11,6 +11,9 @@ public static class LogicalType
         [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_create_logical_type")]
         public static extern DuckDBLogicalType DuckDBCreateLogicalType(DuckDBType type);
 
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_create_decimal_type")]
+        public static extern DuckDBLogicalType DuckDBCreateDecimalType(byte width, byte scale);
+
         [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_get_type_id")]
         public static extern DuckDBType DuckDBGetTypeId(DuckDBLogicalType type);
 

DuckDB.NET.Data/Internal/DuckDBTypeMap.cs

@@ -49,6 +49,7 @@ internal static class DuckDBTypeMap
         { typeof(ulong), DuckDBType.UnsignedBigInt },
         { typeof(float), DuckDBType.Float },
         { typeof(double), DuckDBType.Double},
+        { typeof(Guid), DuckDBType.Uuid},
         { typeof(DateTime), DuckDBType.Timestamp},
         { typeof(TimeSpan), DuckDBType.Interval},
 #if NET6_0_OR_GREATER
@@ -83,6 +84,11 @@ public static DbType GetDbTypeForValue(object? value)
 
     public static DuckDBLogicalType GetLogicalType(Type type)
     {
+        if (type == typeof(decimal))
+        {
+            return NativeMethods.LogicalType.DuckDBCreateDecimalType(38, 18);
+        }
+
         if (ClrToDuckDBTypeMap.TryGetValue(type, out var duckDBType))
         {
             return NativeMethods.LogicalType.DuckDBCreateLogicalType(duckDBType);

DuckDB.NET.Test/TableFunctionTests.cs

@@ -65,7 +65,7 @@ public void RegisterTableFunctionWithThreeParameters()
     {
         var count = 30;
         var startDate = new DateTime(2024, 11, 6);
-        var minutesParam= 10;
+        var minutesParam = 10;
         var secondsParam = 2.5;
 
         Connection.RegisterTableFunction<DateTime, long, double>("demo3", (parameters) =>
@@ -86,6 +86,35 @@ public void RegisterTableFunctionWithThreeParameters()
         var data = Connection.Query<DateTime>($"SELECT * FROM demo3('2024-11-06'::TIMESTAMP, 10, 2.5 );").ToList();
 
         var dateTimes = Enumerable.Range(0, count).Select(i => startDate.AddDays(i).AddMinutes(minutesParam).AddSeconds(secondsParam));
-        data.Select(dateTime => dateTime).Should().BeEquivalentTo(dateTimes);
+        data.Should().BeEquivalentTo(dateTimes);
+    }
+
+    [Fact]
+    public void RegisterTableFunctionWithFourParameters()
+    {
+        var guid = Guid.NewGuid();
+
+        Connection.RegisterTableFunction<bool, decimal, byte, Guid>("demo4", (parameters) =>
+        {
+            var param1 = parameters[0].GetValue<bool>();
+            var param2 = parameters[1].GetValue<decimal>();
+            var param3 = parameters[2].GetValue<byte>();
+            var param4 = parameters[3].GetValue<Guid>();
+            
+            var enumerable = param4.ToByteArray(param1).Append(param3);
+            
+            return new TableFunction(new List<ColumnInfo>()
+            {
+                new ColumnInfo("foo", typeof(byte)),
+            }, enumerable);
+        }, (item, writers, rowIndex) =>
+        {
+            writers[0].WriteValue((byte)item, rowIndex);
+        });
+
+        var data = Connection.Query<byte>($"SELECT * FROM demo4(false, 10::DECIMAL(18, 3), 4::UTINYINT, '{guid}'::UUID );").ToList();
+
+        var bytes = guid.ToByteArray(false).Append((byte)4);
+        data.Should().BeEquivalentTo(bytes);
     }
 }