Fix: Support nullable types in Always Encrypted (microsoft#179)

* preserve type information for Valuer parameters

* support uniqueidentifier in AE

* update readme

Author: shueybubbles

README.md

@@ -427,9 +427,8 @@ If the correct key provider is included in your application, decryption of encry
 
 Encryption of parameters passed to `Exec` and `Query` variants requires an extra round trip per query to fetch the encryption metadata. If the error returned by a query attempt indicates a type mismatch between the parameter and the destination table, most likely your input type is not a strict match for the SQL Server data type of the destination. You may be using a Go `string` when you need to use one of the driver-specific aliases like `VarChar` or `NVarCharMax`.
 
-*** NOTE *** - Currently `char` and `varchar` types do not include a collation parameter component so can't be used for inserting encrypted values. Also, using a nullable sql package type like `sql.NullableInt32` to pass a `NULL` value for an encrypted column will not work unless the encrypted column type is `nvarchar`. 
+*** NOTE *** - Currently `char` and `varchar` types do not include a collation parameter component so can't be used for inserting encrypted values. 
 https://github.com/microsoft/go-mssqldb/issues/129
-https://github.com/microsoft/go-mssqldb/issues/130
 
 
 ### Local certificate AE key provider

alwaysencrypted_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"crypto/rand"
 	"database/sql"
+	"database/sql/driver"
 	"fmt"
 	"math/big"
 	"strings"
@@ -65,8 +66,10 @@ 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}},
+		{"bigint", "BIGINT", ColumnEncryptionDeterministic, sql.NullInt64{Int64: 128, Valid: true}},
+		{"uniqueidentifier", "UNIQUEIDENTIFIER", ColumnEncryptionRandomized, UniqueIdentifier{0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF, 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF}},
+		{"uniqueidentifier", "UNIQUEIDENTIFIER", ColumnEncryptionRandomized, NullUniqueIdentifier{Valid: false}},
 	}
 	for _, test := range providerTests {
 		// turn off key caching
@@ -230,13 +233,19 @@ func comparisonValueFromObject(object interface{}) string {
 	case time.Time:
 		return civil.DateTimeOf(v).String()
 		//return v.Format(time.RFC3339)
-	case fmt.Stringer:
-		return v.String()
 	case bool:
 		if v == true {
 			return "1"
 		}
 		return "0"
+	case driver.Valuer:
+		val, _ := v.Value()
+		if val == nil {
+			return "<nil>"
+		}
+		return comparisonValueFromObject(val)
+	case fmt.Stringer:
+		return v.String()
 	default:
 		return fmt.Sprintf("%v", v)
 	}

mssql.go

@@ -982,7 +982,37 @@ func (s *Stmt) makeParam(val driver.Value) (res param, err error) {
 		res.ti.Size = 0
 		return
 	}
+	switch valuer := val.(type) {
+	case UniqueIdentifier:
+	case NullUniqueIdentifier:
+	default:
+		break
+	case driver.Valuer:
+		// If the value has a non-nil value, call MakeParam on its Value
+		val, e := driver.DefaultParameterConverter.ConvertValue(valuer)
+		if e != nil {
+			err = e
+			return
+		}
+		if val != nil {
+			return s.makeParam(val)
+		}
+	}
 	switch val := val.(type) {
+	case UniqueIdentifier:
+		res.ti.TypeId = typeGuid
+		res.ti.Size = 16
+		guid, _ := val.Value()
+		res.buffer = guid.([]byte)
+	case NullUniqueIdentifier:
+		res.ti.TypeId = typeGuid
+		res.ti.Size = 16
+		if val.Valid {
+			guid, _ := val.Value()
+			res.buffer = guid.([]byte)
+		} else {
+			res.buffer = []byte{}
+		}
 	case int:
 		res.ti.TypeId = typeIntN
 		// Rather than guess if the caller intends to pass a 32bit int from a 64bit app based on the
@@ -1021,6 +1051,10 @@ 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}

mssql_go19.go

@@ -75,6 +75,8 @@ func convertInputParameter(val interface{}) (interface{}, error) {
 	// 	return nil
 	case float32:
 		return val, nil
+	case driver.Valuer:
+		return val, nil
 	default:
 		return driver.DefaultParameterConverter.ConvertValue(v)
 	}

queries_go19_test.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"reflect"
 	"regexp"
+	"strings"
 	"testing"
 	"time"
 
@@ -31,6 +32,32 @@ 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)
+		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) {