preserve type information for Valuer parameters

alwaysencrypted_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"crypto/rand"
 	"database/sql"
+	"database/sql/driver"
 	"fmt"
 	"math/big"
 	"strings"
@@ -65,8 +66,8 @@ func TestAlwaysEncryptedE2E(t *testing.T) {
 		{"datetimeoffset(7)", "DATETIMEOFFSET", ColumnEncryptionRandomized, dt},
 		{"datetime2(7)", "DATETIME2", ColumnEncryptionDeterministic, civil.DateTimeOf(dt)},
 		{"nvarchar(max)", "NVARCHAR", ColumnEncryptionRandomized, NVarCharMax("nvarcharmaxval")},
-		// TODO: The driver throws away type information about Valuer implementations and sends nil as nvarchar(1). Fix that.
-		// {"int", "INT", ColumnEncryptionDeterministic, sql.NullInt32{Valid: false}},
+		{"int", "INT", ColumnEncryptionDeterministic, sql.NullInt32{Valid: false}},
+		{"int", "INT", ColumnEncryptionDeterministic, sql.NullInt64{Int64: 128, Valid: true}},
 	}
 	for _, test := range providerTests {
 		// turn off key caching
@@ -237,6 +238,12 @@ func comparisonValueFromObject(object interface{}) string {
 			return "1"
 		}
 		return "0"
+	case driver.Valuer:
+		val, _ := v.Value()
+		if val == nil {
+			return "<nil>"
+		}
+		return comparisonValueFromObject(val)
 	default:
 		return fmt.Sprintf("%v", v)
 	}

mssql.go

@@ -982,6 +982,17 @@ func (s *Stmt) makeParam(val driver.Value) (res param, err error) {
 		res.ti.Size = 0
 		return
 	}
+	// If the value has a non-nil value, call MakeParam on its Value
+	if valuer, ok := val.(driver.Valuer); ok {
+		val, e := driver.DefaultParameterConverter.ConvertValue(valuer)
+		if e != nil {
+			err = e
+			return
+		}
+		if val != nil {
+			return s.makeParam(val)
+		}
+	}
 	switch val := val.(type) {
 	case int:
 		res.ti.TypeId = typeIntN
@@ -1021,6 +1032,10 @@ func (s *Stmt) makeParam(val driver.Value) (res param, err error) {
 		res.ti.TypeId = typeIntN
 		res.ti.Size = 8
 		res.buffer = []byte{}
+	case sql.NullInt32:
+		res.ti.TypeId = typeIntN
+		res.ti.Size = 4
+		res.buffer = []byte{}
 	case byte:
 		res.ti.TypeId = typeIntN
 		res.buffer = []byte{val}

queries_go19_test.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"reflect"
 	"regexp"
+	"strings"
 	"testing"
 	"time"
 
@@ -31,6 +32,36 @@ func TestOutputParam(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
+	t.Run("varchar(max) to sql.NullString", func(t *testing.T) {
+		sqltextcreate := `CREATE PROCEDURE [GetTask]
+		@strparam varchar(max) = NULL OUTPUT
+	AS
+	SELECT @strparam = REPLICATE('a', 8000)
+	RETURN 0`
+		sqltextdrop := `drop procedure GetTask`
+		sqltextrun := `GetTask`
+		_, _ = db.ExecContext(ctx, sqltextdrop)
+		_, err = db.ExecContext(ctx, sqltextcreate)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer db.ExecContext(ctx, sqltextdrop)
+		if err != nil {
+			t.Error(err)
+		}
+
+		nullstr := sql.NullString{}
+		_, err := db.ExecContext(ctx, sqltextrun,
+			sql.Named("strparam", sql.Out{Dest: &nullstr}),
+		)
+		if err != nil {
+			t.Error(err)
+		}
+		defer db.ExecContext(ctx, sqltextdrop)
+		if nullstr.String != strings.Repeat("a", 8000) {
+			t.Error("Got incorrect NullString of length:", len(nullstr.String))
+		}
+	})
 	t.Run("sp with rows", func(t *testing.T) {
 		sqltextcreate := `
 CREATE PROCEDURE spwithrows

queries_test.go

@@ -198,6 +198,19 @@ func TestSelect(t *testing.T) {
 			}
 		})
 	})
+	t.Run("scan into sql.NullString", func(t *testing.T) {
+		row := conn.QueryRow("SELECT REPLICATE('a', 8000)")
+		var out sql.NullString
+		err := row.Scan(&out)
+		if err != nil {
+			t.Error("Scan to NullString failed", err.Error())
+			return
+		}
+
+		if out.String != strings.Repeat("a", 8000) {
+			t.Error("got back a string with count:", len(out.String))
+		}
+	})
 }
 
 func TestSelectDateTimeOffset(t *testing.T) {