* Fixed bug from scan unexpected column name (#418)

Author: asmyasnikov

CHANGELOG.md

@@ -1,3 +1,5 @@
+* Fixed bug from scan unexpected column name
+
 ## v3.38.4
 * Changed type of `table/options.{Create,Alter,Drop}TableOption` from func to interface
 * Added implementations of `table/options.{Create,Alter,Drop}Option`

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/stretchr/testify v1.7.1
 	github.com/ydb-platform/ydb-go-genproto v0.0.0-20220922065549-66df47a830ba
 	golang.org/x/sync v0.0.0-20220601150217-0de741cfad7f
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1
 	google.golang.org/grpc v1.47.0
 	google.golang.org/protobuf v1.28.0
 )

internal/table/scanner/scanner.go

@@ -1,7 +1,6 @@
 package scanner
 
 import (
-	"bytes"
 	"database/sql"
 	"encoding/json"
 	"errors"
@@ -15,6 +14,7 @@ import (
 
 	"github.com/ydb-platform/ydb-go-sdk/v3/internal/timeutil"
 	"github.com/ydb-platform/ydb-go-sdk/v3/internal/value"
+	"github.com/ydb-platform/ydb-go-sdk/v3/internal/value/allocator"
 	"github.com/ydb-platform/ydb-go-sdk/v3/internal/xerrors"
 	"github.com/ydb-platform/ydb-go-sdk/v3/internal/xsync"
 	"github.com/ydb-platform/ydb-go-sdk/v3/table/options"
@@ -173,9 +173,9 @@ func (s *scanner) Scan(values ...indexed.RequiredOrOptional) (err error) {
 	return s.Err()
 }
 
-func (s *scanner) ScanNamed(namedValues ...named.Value) (err error) {
-	if err = s.Err(); err != nil {
-		return
+func (s *scanner) ScanNamed(namedValues ...named.Value) error {
+	if err := s.Err(); err != nil {
+		return err
 	}
 	if s.ColumnCount() < len(namedValues) {
 		panic(fmt.Sprintf("scan row failed: count of columns less then values (%d < %d)", s.ColumnCount(), len(namedValues)))
@@ -184,8 +184,8 @@ func (s *scanner) ScanNamed(namedValues ...named.Value) (err error) {
 		panic("scan row failed: double scan per row")
 	}
 	for _, v := range namedValues {
-		if err = s.seekItemByName(v.Name); err != nil {
-			return
+		if err := s.seekItemByName(v.Name); err != nil {
+			return err
 		}
 		switch t := v.Type; t {
 		case named.TypeRequired:
@@ -250,8 +250,9 @@ func (s *scanner) reset(set *Ydb.ResultSet, columnNames ...string) {
 }
 
 func (s *scanner) path() string {
-	var buf bytes.Buffer
-	_, _ = s.writePathTo(&buf)
+	buf := allocator.Buffers.Get()
+	defer allocator.Buffers.Put(buf)
+	_, _ = s.writePathTo(buf)
 	return buf.String()
 }
 
@@ -280,7 +281,7 @@ func (s *scanner) hasItems() bool {
 
 func (s *scanner) seekItemByID(id int) error {
 	if !s.hasItems() || id >= len(s.set.Columns) {
-		return s.noValueError()
+		return s.notFoundColumnByIndex(id)
 	}
 	col := s.set.Columns[id]
 	s.stack.scanItem.name = col.Name
@@ -291,7 +292,7 @@ func (s *scanner) seekItemByID(id int) error {
 
 func (s *scanner) seekItemByName(name string) error {
 	if !s.hasItems() {
-		return s.noValueError()
+		return s.notFoundColumnName(name)
 	}
 	for i, c := range s.set.Columns {
 		if name == c.Name {
@@ -301,7 +302,7 @@ func (s *scanner) seekItemByName(name string) error {
 			return s.Err()
 		}
 	}
-	return s.noValueError()
+	return s.notFoundColumnName(name)
 }
 
 func (s *scanner) setColumnIndexes(columns []string) {
@@ -1123,11 +1124,19 @@ func (s *scanner) valueTypeError(act, exp interface{}) {
 	)
 }
 
-func (s *scanner) noValueError() error {
+func (s *scanner) notFoundColumnByIndex(idx int) error {
 	return s.errorf(
 		2,
-		"no value at %q",
-		s.path(),
+		"not found %d column",
+		idx,
+	)
+}
+
+func (s *scanner) notFoundColumnName(name string) error {
+	return s.errorf(
+		2,
+		"not found column '%s'",
+		name,
 	)
 }
 

table/table_regress_test.go

@@ -5,14 +5,17 @@ package table_test
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"testing"
 	"time"
 
 	"github.com/stretchr/testify/require"
+	"golang.org/x/xerrors"
 
 	"github.com/ydb-platform/ydb-go-sdk/v3"
 	"github.com/ydb-platform/ydb-go-sdk/v3/table"
+	"github.com/ydb-platform/ydb-go-sdk/v3/table/result/named"
 	"github.com/ydb-platform/ydb-go-sdk/v3/table/types"
 )
 
@@ -115,3 +118,50 @@ func TestIssue259IntervalFromDuration(t *testing.T) {
 	})
 	require.NoError(t, err)
 }
+
+func TestIssue415ScanError(t *testing.T) {
+	// https://github.com/ydb-platform/ydb-go-sdk/issues/415
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	db := connect(t)
+	defer db.Close(ctx)
+	err := db.Table().DoTx(ctx, func(ctx context.Context, tx table.TransactionActor) error {
+		res, err := tx.Execute(ctx, `SELECT 1 as abc, 2 as def;`, nil)
+		if err != nil {
+			return err
+		}
+		err = res.NextResultSetErr(ctx)
+		if err != nil {
+			return err
+		}
+		if !res.NextRow() {
+			if err = res.Err(); err != nil {
+				return err
+			}
+			return fmt.Errorf("unexpected empty result set")
+		}
+		var abc, def int32
+		err = res.ScanNamed(
+			named.Required("abc", &abc),
+			named.Required("ghi", &def),
+		)
+		if err != nil {
+			return err
+		}
+		fmt.Println(abc, def)
+		return res.Err()
+	}, table.WithTxSettings(table.TxSettings(table.WithSnapshotReadOnly())))
+	require.Error(t, err)
+	err = func(err error) error {
+		for {
+			//nolint:errorlint
+			if unwrappedErr, has := err.(xerrors.Wrapper); has {
+				err = unwrappedErr.Unwrap()
+			} else {
+				return err
+			}
+		}
+	}(err)
+	require.Equal(t, "not found column 'ghi'", err.Error())
+}