fix: correctly encode DateTime parameters for MSSQL RPC calls

Author: vkuttyp

Directory.Build.props

@@ -7,6 +7,6 @@
     <Authors>vkuttyp</Authors>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
     <RepositoryUrl>https://github.com/vkuttyp/CosmoSQLClient-Dotnet</RepositoryUrl>
-    <Version>1.9.1</Version>
+    <Version>1.9.3</Version>
   </PropertyGroup>
 </Project>

src/CosmoSQLClient.MsSql/MsSqlConnection.cs

@@ -500,7 +500,7 @@ private static string BuildParamDeclarations(IReadOnlyList<SqlParameter> paramet
     private static string SqlValueToTypeName(SqlValue v) => v switch {
         SqlValue.Bool => "BIT", SqlValue.Int32 => "INT", SqlValue.Int64 => "BIGINT",
         SqlValue.Float => "REAL", SqlValue.Double => "FLOAT", SqlValue.Decimal => "DECIMAL(38,10)",
-        SqlValue.Date => "DATETIME2", SqlValue.Uuid => "UNIQUEIDENTIFIER", _ => "NVARCHAR(MAX)"
+        SqlValue.Date => "DATETIME", SqlValue.Uuid => "UNIQUEIDENTIFIER", _ => "NVARCHAR(MAX)"
     };
 
     private static void WriteAllHeaders(BinaryWriter bw, long tx) {
@@ -548,6 +548,22 @@ private static void WriteNamedParam(BinaryWriter bw, string name, SqlValue value
             case SqlValue.Text v:
                 WriteNvarcharMaxTypeAndValue(bw, v.Value);
                 break;
+            case SqlValue.Date v:
+                bw.Write((byte)0x6F); // DATETIMN
+                bw.Write((byte)0x08); // Max length for DATETIME
+                bw.Write((byte)0x08); // Actual data length
+                // Encode as DATETIME (8 bytes)
+                var dt = v.Value;
+                var days = (int)(dt.Date - new DateTime(1900, 1, 1)).TotalDays;
+                var ticks = (int)(dt.TimeOfDay.TotalSeconds * 300);
+                bw.Write(days);
+                bw.Write(ticks);
+                break;
+            case SqlValue.Uuid v:
+                bw.Write((byte)0x24); // UNIQUEIDENTIFIER
+                bw.Write((byte)0x10); // length
+                bw.Write(v.Value.ToByteArray());
+                break;
             default:
                 WriteNvarcharMaxTypeAndValue(bw, value.AsString());
                 break;

tests/CosmoSQLClient.MsSql.Tests/AdoNetTests.cs

@@ -131,6 +131,22 @@ public async Task StandardAdoNet_AddWithValue_Abstraction_ShouldWork()
         Assert.Equal("Hello Extension", result);
     }
 
+    [Fact]
+    public async Task StandardAdoNet_DateTimeParameter_ShouldWork()
+    {
+        if (ShouldSkip) return;
+
+        using var conn = new MsSqlConnection(ConnectionString);
+        await conn.OpenAsync();
+
+        using var cmd = new MsSqlCommand("SELECT @val AS Echo", conn);
+        var now = new DateTime(2023, 10, 27, 12, 34, 56);
+        cmd.Parameters.AddWithValue("@val", now);
+
+        var result = await cmd.ExecuteScalarAsync();
+        Assert.Equal(now, (DateTime)result!);
+    }
+
     [Fact]
     public async Task StandardAdoNet_Transactions_ShouldWork()
     {