Improve error messages for scan errors on all adapters

adapters/kmysql/sql_adapter.go

@@ -3,6 +3,9 @@ package kmysql
 import (
 	"context"
 	"database/sql"
+	"strconv"
+	"strings"
+	"unicode"
 
 	"github.com/vingarcia/ksql"
 )
@@ -29,7 +32,8 @@ func (s SQLAdapter) ExecContext(ctx context.Context, query string, args ...inter
 
 // QueryContext implements the DBAdapter interface
 func (s SQLAdapter) QueryContext(ctx context.Context, query string, args ...interface{}) (ksql.Rows, error) {
-	return s.DB.QueryContext(ctx, query, args...)
+	rows, err := s.DB.QueryContext(ctx, query, args...)
+	return SQLRows{rows}, err
 }
 
 // BeginTx implements the Tx interface
@@ -56,7 +60,8 @@ func (s SQLTx) ExecContext(ctx context.Context, query string, args ...interface{
 
 // QueryContext implements the Tx interface
 func (s SQLTx) QueryContext(ctx context.Context, query string, args ...interface{}) (ksql.Rows, error) {
-	return s.Tx.QueryContext(ctx, query, args...)
+	rows, err := s.Tx.QueryContext(ctx, query, args...)
+	return SQLRows{rows}, err
 }
 
 // Rollback implements the Tx interface
@@ -70,3 +75,40 @@ func (s SQLTx) Commit(ctx context.Context) error {
 }
 
 var _ ksql.Tx = SQLTx{}
+
+// SQLRows implements the ksql.Rows interface and is used to help
+// the SQLAdapter to implement the ksql.DBAdapter interface.
+type SQLRows struct {
+	*sql.Rows
+}
+
+var _ ksql.Rows = SQLRows{}
+
+// Scan implements the ksql.Rows interface
+func (p SQLRows) Scan(args ...interface{}) error {
+	err := p.Rows.Scan(args...)
+	if err != nil {
+		// Since this is the error flow we decided it would be ok
+		// to spend a little bit more time parsing this error in order
+		// to produce better error messages.
+		//
+		// If the parsing fails we just return the error unchanged.
+		const scanErrPrefix = "sql: Scan error on column index "
+		var errMsg = err.Error()
+		if strings.HasPrefix(errMsg, scanErrPrefix) {
+			i := len(scanErrPrefix)
+			for unicode.IsDigit(rune(errMsg[i])) {
+				i++
+			}
+			colIndex, convErr := strconv.Atoi(errMsg[len(scanErrPrefix):i])
+			if convErr == nil {
+				return ksql.ScanArgError{
+					ColumnIndex: colIndex,
+					Err:         err,
+				}
+			}
+		}
+	}
+
+	return err
+}

adapters/kpgx/pgx_adapter.go

@@ -96,14 +96,27 @@ func (p PGXTx) Commit(ctx context.Context) error {
 
 var _ ksql.Tx = PGXTx{}
 
-// PGXRows implements the Rows interface and is used to help
+// PGXRows implements the ksql.Rows interface and is used to help
-// the PGXAdapter to implement the DBAdapter interface.
+// the PGXAdapter to implement the ksql.DBAdapter interface.
 type PGXRows struct {
 	pgx.Rows
 }
 
 var _ ksql.Rows = PGXRows{}
 
+// Scan implements the ksql.Rows interface
+func (p PGXRows) Scan(args ...interface{}) error {
+	err := p.Rows.Scan(args...)
+	if scanErr, ok := err.(pgx.ScanArgError); ok {
+		return ksql.ScanArgError{
+			Err:         scanErr.Err,
+			ColumnIndex: scanErr.ColumnIndex,
+		}
+	}
+
+	return err
+}
+
 // Columns implements the Rows interface
 func (p PGXRows) Columns() ([]string, error) {
 	var names []string

adapters/ksqlite3/sql_adapter.go

@@ -3,6 +3,9 @@ package ksqlite3
 import (
 	"context"
 	"database/sql"
+	"strconv"
+	"strings"
+	"unicode"
 
 	"github.com/vingarcia/ksql"
 )
@@ -29,7 +32,8 @@ func (s SQLAdapter) ExecContext(ctx context.Context, query string, args ...inter
 
 // QueryContext implements the DBAdapter interface
 func (s SQLAdapter) QueryContext(ctx context.Context, query string, args ...interface{}) (ksql.Rows, error) {
-	return s.DB.QueryContext(ctx, query, args...)
+	rows, err := s.DB.QueryContext(ctx, query, args...)
+	return SQLRows{rows}, err
 }
 
 // BeginTx implements the Tx interface
@@ -56,7 +60,8 @@ func (s SQLTx) ExecContext(ctx context.Context, query string, args ...interface{
 
 // QueryContext implements the Tx interface
 func (s SQLTx) QueryContext(ctx context.Context, query string, args ...interface{}) (ksql.Rows, error) {
-	return s.Tx.QueryContext(ctx, query, args...)
+	rows, err := s.Tx.QueryContext(ctx, query, args...)
+	return SQLRows{rows}, err
 }
 
 // Rollback implements the Tx interface
@@ -70,3 +75,40 @@ func (s SQLTx) Commit(ctx context.Context) error {
 }
 
 var _ ksql.Tx = SQLTx{}
+
+// SQLRows implements the ksql.Rows interface and is used to help
+// the SQLAdapter to implement the ksql.DBAdapter interface.
+type SQLRows struct {
+	*sql.Rows
+}
+
+var _ ksql.Rows = SQLRows{}
+
+// Scan implements the ksql.Rows interface
+func (p SQLRows) Scan(args ...interface{}) error {
+	err := p.Rows.Scan(args...)
+	if err != nil {
+		// Since this is the error flow we decided it would be ok
+		// to spend a little bit more time parsing this error in order
+		// to produce better error messages.
+		//
+		// If the parsing fails we just return the error unchanged.
+		const scanErrPrefix = "sql: Scan error on column index "
+		var errMsg = err.Error()
+		if strings.HasPrefix(errMsg, scanErrPrefix) {
+			i := len(scanErrPrefix)
+			for unicode.IsDigit(rune(errMsg[i])) {
+				i++
+			}
+			colIndex, convErr := strconv.Atoi(errMsg[len(scanErrPrefix):i])
+			if convErr == nil {
+				return ksql.ScanArgError{
+					ColumnIndex: colIndex,
+					Err:         err,
+				}
+			}
+		}
+	}
+
+	return err
+}

adapters/ksqlserver/sql_adapter.go

@@ -3,6 +3,9 @@ package ksqlserver
 import (
 	"context"
 	"database/sql"
+	"strconv"
+	"strings"
+	"unicode"
 
 	"github.com/vingarcia/ksql"
 )
@@ -29,7 +32,8 @@ func (s SQLAdapter) ExecContext(ctx context.Context, query string, args ...inter
 
 // QueryContext implements the DBAdapter interface
 func (s SQLAdapter) QueryContext(ctx context.Context, query string, args ...interface{}) (ksql.Rows, error) {
-	return s.DB.QueryContext(ctx, query, args...)
+	rows, err := s.DB.QueryContext(ctx, query, args...)
+	return SQLRows{rows}, err
 }
 
 // BeginTx implements the Tx interface
@@ -56,7 +60,8 @@ func (s SQLTx) ExecContext(ctx context.Context, query string, args ...interface{
 
 // QueryContext implements the Tx interface
 func (s SQLTx) QueryContext(ctx context.Context, query string, args ...interface{}) (ksql.Rows, error) {
-	return s.Tx.QueryContext(ctx, query, args...)
+	rows, err := s.Tx.QueryContext(ctx, query, args...)
+	return SQLRows{rows}, err
 }
 
 // Rollback implements the Tx interface
@@ -70,3 +75,40 @@ func (s SQLTx) Commit(ctx context.Context) error {
 }
 
 var _ ksql.Tx = SQLTx{}
+
+// SQLRows implements the ksql.Rows interface and is used to help
+// the SQLAdapter to implement the ksql.DBAdapter interface.
+type SQLRows struct {
+	*sql.Rows
+}
+
+var _ ksql.Rows = SQLRows{}
+
+// Scan implements the ksql.Rows interface
+func (p SQLRows) Scan(args ...interface{}) error {
+	err := p.Rows.Scan(args...)
+	if err != nil {
+		// Since this is the error flow we decided it would be ok
+		// to spend a little bit more time parsing this error in order
+		// to produce better error messages.
+		//
+		// If the parsing fails we just return the error unchanged.
+		const scanErrPrefix = "sql: Scan error on column index "
+		var errMsg = err.Error()
+		if strings.HasPrefix(errMsg, scanErrPrefix) {
+			i := len(scanErrPrefix)
+			for unicode.IsDigit(rune(errMsg[i])) {
+				i++
+			}
+			colIndex, convErr := strconv.Atoi(errMsg[len(scanErrPrefix):i])
+			if convErr == nil {
+				return ksql.ScanArgError{
+					ColumnIndex: colIndex,
+					Err:         err,
+				}
+			}
+		}
+	}
+
+	return err
+}

examples/go.mod

@@ -12,7 +12,7 @@ replace (
 
 require (
 	github.com/golang/mock v1.6.0
-	github.com/stretchr/testify v1.7.0
+	github.com/stretchr/testify v1.8.0
 	github.com/vingarcia/ksql v1.4.7
 	github.com/vingarcia/ksql/adapters/kmysql v0.0.0-00010101000000-000000000000
 	github.com/vingarcia/ksql/adapters/kpgx v0.0.0-00010101000000-000000000000

examples/go.sum

@@ -230,12 +230,15 @@ github.com/spf13/viper v1.4.0/go.mod h1:PTJ7Z/lr49W6bUbkmS1V3by4uWynFiR9p7+dSq/y
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.2.0/go.mod h1:qt09Ya8vawLte6SNmTgCsAVtYtaKzEcn8ATUoHMkEqE=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/syndtr/gocapability v0.0.0-20200815063812-42c35b437635/go.mod h1:hkRG7XYTFWNJGYcbNJQlaLq0fg1yr4J4t/NcTQtrfww=
 github.com/tmc/grpc-websocket-proxy v0.0.0-20190109142713-0ad062ec5ee5/go.mod h1:ncp9v5uamzpCO7NfCPTXjqaC+bZgJeR0sMTm6dMHP7U=
 github.com/tv42/httpunix v0.0.0-20191220191345-2ba4b9c3382c/go.mod h1:hzIxponao9Kjc7aWznkXaL4U4TWaDSs8zcsY4Ka08nM=
@@ -371,8 +374,9 @@ gopkg.in/resty.v1 v1.12.0/go.mod h1:mDo4pnntr5jdWRML875a/NmxYqAlA73dVijT2AXvQQo=
 gopkg.in/yaml.v2 v2.0.0-20170812160011-eb3733d160e7/go.mod h1:JAlM8MvJe8wmxCU4Bli9HhUf9+ttbYbLASfIpnQbh74=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gotest.tools v2.2.0+incompatible h1:VsBPFP1AI068pPrMxtb/S8Zkgf9xEmTLJjfM+P5UIEo=
 gotest.tools v2.2.0+incompatible/go.mod h1:DsYFclhRJ6vuDpmuTbkuFWG+y2sxOXAzmJt81HFBacw=
 honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=

internal/structs/structs.go

@@ -23,7 +23,8 @@ type StructInfo struct {
 // information regarding a specific field
 // of a struct.
 type FieldInfo struct {
-	Name     string
+	AttrName   string
+	ColumnName string
 	Index      int
 	Valid      bool
 	Modifier   ksqlmodifiers.AttrModifier
@@ -52,12 +53,12 @@ func (s StructInfo) ByName(name string) *FieldInfo {
 func (s StructInfo) add(field FieldInfo) {
 	field.Valid = true
 	s.byIndex[field.Index] = &field
-	s.byName[field.Name] = &field
+	s.byName[field.ColumnName] = &field
 
 	// Make sure to save a lowercased version because
 	// some databases will set these keys to lowercase.
-	if _, found := s.byName[strings.ToLower(field.Name)]; !found {
+	if _, found := s.byName[strings.ToLower(field.ColumnName)]; !found {
-		s.byName[strings.ToLower(field.Name)] = &field
+		s.byName[strings.ToLower(field.ColumnName)] = &field
 	}
 }
 
@@ -143,7 +144,7 @@ func StructToMap(obj interface{}) (map[string]interface{}, error) {
 			field = field.Elem()
 		}
 
-		m[fieldInfo.Name] = field.Interface()
+		m[fieldInfo.ColumnName] = field.Interface()
 	}
 
 	return m, nil
@@ -246,6 +247,7 @@ func getTagNames(t reflect.Type) (_ StructInfo, err error) {
 			return StructInfo{}, fmt.Errorf("all fields using the ksql tags must be exported, but %v is unexported", t)
 		}
 
+		attrName := t.Field(i).Name
 		name := t.Field(i).Tag.Get("ksql")
 		if name == "" {
 			continue
@@ -269,7 +271,8 @@ func getTagNames(t reflect.Type) (_ StructInfo, err error) {
 		}
 
 		info.add(FieldInfo{
-			Name:     name,
+			AttrName:   attrName,
+			ColumnName: name,
 			Index:      i,
 			Modifier:   modifier,
 		})
@@ -289,7 +292,8 @@ func getTagNames(t reflect.Type) (_ StructInfo, err error) {
 		}
 
 		info.add(FieldInfo{
-			Name:  name,
+			AttrName:   t.Field(i).Name,
+			ColumnName: name,
 			Index:      i,
 		})
 	}

kbuilder/insert.go

@@ -81,7 +81,7 @@ func (i Insert) BuildQuery(dialect ksql.Dialect) (sqlQuery string, params []inte
 	b.WriteString(" (")
 	var escapedNames []string
 	for i := 0; i < info.NumFields(); i++ {
-		name := info.ByIndex(i).Name
+		name := info.ByIndex(i).ColumnName
 		escapedNames = append(escapedNames, dialect.Escape(name))
 	}
 	b.WriteString(strings.Join(escapedNames, ", "))

kbuilder/query.go

@@ -215,7 +215,7 @@ func buildSelectQuery(obj interface{}, dialect ksql.Dialect) (string, error) {
 
 	var escapedNames []string
 	for i := 0; i < info.NumFields(); i++ {
-		name := info.ByIndex(i).Name
+		name := info.ByIndex(i).ColumnName
 		escapedNames = append(escapedNames, dialect.Escape(name))
 	}
 

ksql.go

@@ -67,6 +67,34 @@ type Rows interface {
 	Columns() ([]string, error)
 }
 
+// ScanArgError is a type of error that is expected to be returned
+// from the Scan() method of the Rows interface.
+//
+// It should be returned when there is an error scanning one of the input
+// values.
+//
+// This is necessary in order to allow KSQL to produce a better and more
+// readable error message when this type of error occur.
+type ScanArgError struct {
+	ColumnIndex int
+	Err         error
+}
+
+// Error implements the error interface.
+func (s ScanArgError) Error() string {
+	return fmt.Sprintf(
+		"error scanning input attribute with index %d: %s",
+		s.ColumnIndex, s.Err.Error(),
+	)
+}
+
+func (s ScanArgError) ErrorWithStructNames(structName string, colName string) error {
+	return fmt.Errorf(
+		"error scanning %s.%s: %s",
+		structName, colName, s.Err.Error(),
+	)
+}
+
 // Tx represents a transaction and is expected to be returned by the DBAdapter.BeginTx function
 type Tx interface {
 	DBAdapter
@@ -1002,27 +1030,34 @@ func scanRowsFromType(
 		return err
 	}
 
+	var attrNames []string
 	var scanArgs []interface{}
 	if info.IsNestedStruct {
 		// This version is positional meaning that it expect the arguments
 		// to follow an specific order. It's ok because we don't allow the
 		// user to type the "SELECT" part of the query for nested structs.
-		scanArgs, err = getScanArgsForNestedStructs(ctx, dialect, rows, t, v, info)
+		attrNames, scanArgs, err = getScanArgsForNestedStructs(ctx, dialect, rows, t, v, info)
 		if err != nil {
 			return err
 		}
 	} else {
-		names, err := rows.Columns()
+		colNames, err := rows.Columns()
 		if err != nil {
 			return fmt.Errorf("KSQL: unable to read columns from returned rows: %w", err)
 		}
 		// Since this version uses the names of the columns it works
 		// with any order of attributes/columns.
-		scanArgs = getScanArgsFromNames(ctx, dialect, names, v, info)
+		attrNames, scanArgs = getScanArgsFromNames(ctx, dialect, colNames, v, info)
 	}
 
 	err = rows.Scan(scanArgs...)
 	if err != nil {
+		if scanErr, ok := err.(ScanArgError); ok {
+			return fmt.Errorf(
+				"KSQL: scan error: %w",
+				scanErr.ErrorWithStructNames(t.Name(), attrNames[scanErr.ColumnIndex]),
+			)
+		}
 		return fmt.Errorf("KSQL: scan error: %w", err)
 	}
 	return nil
@@ -1035,8 +1070,7 @@ func getScanArgsForNestedStructs(
 	t reflect.Type,
 	v reflect.Value,
 	info structs.StructInfo,
-) ([]interface{}, error) {
+) (attrNames []string, scanArgs []interface{}, _ error) {
-	scanArgs := []interface{}{}
 	for i := 0; i < v.NumField(); i++ {
 		if !info.ByIndex(i).Valid {
 			continue
@@ -1045,7 +1079,7 @@ func getScanArgsForNestedStructs(
 		// TODO(vingarcia00): Handle case where type is pointer
 		nestedStructInfo, err := structs.GetTagInfo(t.Field(i).Type)
 		if err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 
 		nestedStructValue := v.Field(i)
@@ -1055,10 +1089,7 @@ func getScanArgsForNestedStructs(
 				continue
 			}
 
-			valueScanner := nopScannerValue
+			valueScanner := nestedStructValue.Field(fieldInfo.Index).Addr().Interface()
-			if fieldInfo.Valid {
-				valueScanner = nestedStructValue.Field(fieldInfo.Index).Addr().Interface()
-
 			if fieldInfo.Modifier.Scan != nil {
 				valueScanner = &modifiers.AttrScanWrapper{
 					Ctx:     ctx,
@@ -1072,17 +1103,22 @@ func getScanArgsForNestedStructs(
 					},
 				}
 			}
-			}
 
 			scanArgs = append(scanArgs, valueScanner)
+			attrNames = append(attrNames, info.ByIndex(i).AttrName+"."+fieldInfo.AttrName)
 		}
 	}
 
-	return scanArgs, nil
+	return attrNames, scanArgs, nil
 }
 
-func getScanArgsFromNames(ctx context.Context, dialect Dialect, names []string, v reflect.Value, info structs.StructInfo) []interface{} {
+func getScanArgsFromNames(
-	scanArgs := []interface{}{}
+	ctx context.Context,
+	dialect Dialect,
+	names []string,
+	v reflect.Value,
+	info structs.StructInfo,
+) (attrNames []string, scanArgs []interface{}) {
 	for _, name := range names {
 		fieldInfo := info.ByName(name)
 
@@ -1105,9 +1141,10 @@ func getScanArgsFromNames(ctx context.Context, dialect Dialect, names []string,
 		}
 
 		scanArgs = append(scanArgs, valueScanner)
+		attrNames = append(attrNames, fieldInfo.AttrName)
 	}
 
-	return scanArgs
+	return attrNames, scanArgs
 }
 
 func buildDeleteQuery(
@@ -1185,7 +1222,7 @@ func buildSelectQueryForPlainStructs(
 			continue
 		}
 
-		fields = append(fields, dialect.Escape(fieldInfo.Name))
+		fields = append(fields, dialect.Escape(fieldInfo.ColumnName))
 	}
 
 	return "SELECT " + strings.Join(fields, ", ") + " "
@@ -1203,7 +1240,7 @@ func buildSelectQueryForNestedStructs(
 			continue
 		}
 
-		nestedStructName := nestedStructInfo.Name
+		nestedStructName := nestedStructInfo.ColumnName
 		nestedStructType := structType.Field(i).Type
 		if nestedStructType.Kind() != reflect.Struct {
 			return "", fmt.Errorf(
@@ -1225,7 +1262,7 @@ func buildSelectQueryForNestedStructs(
 
 			fields = append(
 				fields,
-				dialect.Escape(nestedStructName)+"."+dialect.Escape(fieldInfo.Name),
+				dialect.Escape(nestedStructName)+"."+dialect.Escape(fieldInfo.ColumnName),
 			)
 		}
 	}

test_adapters.go

@@ -6,10 +6,13 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"reflect"
+	"strings"
 	"testing"
 	"time"
 
 	"github.com/vingarcia/ksql/internal/modifiers"
+	"github.com/vingarcia/ksql/internal/structs"
 	tt "github.com/vingarcia/ksql/internal/testtools"
 	"github.com/vingarcia/ksql/ksqlmodifiers"
 	"github.com/vingarcia/ksql/nullable"
@@ -37,6 +40,8 @@ type address struct {
 	Country string `json:"country"`
 }
 
+var postsTable = NewTable("posts")
+
 type post struct {
 	ID     int    `ksql:"id"`
 	UserID uint   `ksql:"user_id"`
@@ -1017,7 +1022,6 @@ func InsertTest(
 					tt.AssertNoErr(t, err)
 					tt.AssertNotEqual(t, permission.ID, 0)
 
-					fmt.Println("permID:", permission.ID)
 					var untaggedPerm struct {
 						ID     uint    `ksql:"id"`
 						UserID int     `ksql:"user_id"`
@@ -3050,6 +3054,8 @@ func ScanRowsTest(
 	connStr string,
 	newDBAdapter func(t *testing.T) (DBAdapter, io.Closer),
 ) {
+	ctx := context.Background()
+
 	t.Run("ScanRows", func(t *testing.T) {
 		t.Run("should scan users correctly", func(t *testing.T) {
 			err := createTables(driver, connStr)
@@ -3058,7 +3064,6 @@ func ScanRowsTest(
 			}
 
 			dialect := supportedDialects[driver]
-			ctx := context.TODO()
 			db, closer := newDBAdapter(t)
 			defer closer.Close()
 			c := newTestDB(db, driver)
@@ -3082,12 +3087,9 @@ func ScanRowsTest(
 
 		t.Run("should ignore extra columns from query", func(t *testing.T) {
 			err := createTables(driver, connStr)
-			if err != nil {
+			tt.AssertNoErr(t, err)
-				t.Fatal("could not create test table!, reason:", err.Error())
-			}
 
 			dialect := supportedDialects[driver]
-			ctx := context.TODO()
 			db, closer := newDBAdapter(t)
 			defer closer.Close()
 			c := newTestDB(db, driver)
@@ -3112,6 +3114,101 @@ func ScanRowsTest(
 			tt.AssertEqual(t, u.Age, 22)
 		})
 
+		t.Run("should report scan errors", func(t *testing.T) {
+			type brokenUser struct {
+				ID uint `ksql:"id"`
+
+				// The error will happen here, when scanning
+				// an integer into a attribute of type struct{}:
+				Age struct{} `ksql:"age"`
+			}
+
+			type brokenNestedStruct struct {
+				User struct {
+					ID uint `ksql:"id"`
+
+					// The error will happen here, when scanning
+					// an integer into a attribute of type struct:
+					Age struct{} `ksql:"age"`
+				} `tablename:"u"`
+				Post post `tablename:"p"`
+			}
+
+			tests := []struct {
+				desc               string
+				query              string
+				scanTarget         interface{}
+				expectErrToContain []string
+			}{
+				{
+					desc:  "with anonymous structs",
+					query: "FROM users WHERE name='User22'",
+					scanTarget: &struct {
+						ID uint `ksql:"id"`
+
+						// The error will happen here, when scanning
+						// an integer into a attribute of type struct{}:
+						Age struct{} `ksql:"age"`
+					}{},
+					expectErrToContain: []string{" .Age", "struct {}"},
+				},
+				{
+					desc:               "with named structs",
+					query:              "FROM users WHERE name='User22'",
+					scanTarget:         &brokenUser{},
+					expectErrToContain: []string{"brokenUser.Age", "struct {}"},
+				},
+				{
+					desc:  "with anonymous nested structs",
+					query: "FROM users u JOIN posts p ON u.id = p.user_id WHERE name='User22'",
+					scanTarget: &struct {
+						User struct {
+							ID uint `ksql:"id"`
+
+							// The error will happen here, when scanning
+							// an integer into a attribute of type struct:
+							Age struct{} `ksql:"age"`
+						} `tablename:"u"`
+						Post post `tablename:"p"`
+					}{},
+					expectErrToContain: []string{".User.Age", "struct {}"},
+				},
+				{
+					desc:               "with named nested structs",
+					query:              "FROM users u JOIN posts p ON u.id = p.user_id WHERE name='User22'",
+					scanTarget:         &brokenNestedStruct{},
+					expectErrToContain: []string{"brokenNestedStruct.User.Age", "struct {}"},
+				},
+			}
+
+			for _, test := range tests {
+				t.Run(test.desc, func(t *testing.T) {
+					err := createTables(driver, connStr)
+					tt.AssertNoErr(t, err)
+
+					dialect := supportedDialects[driver]
+					db, closer := newDBAdapter(t)
+					defer closer.Close()
+					c := newTestDB(db, driver)
+
+					u := user{Name: "User22", Age: 22}
+					_ = c.Insert(ctx, usersTable, &u)
+					_ = c.Insert(ctx, postsTable, &post{UserID: u.ID, Title: "FakeTitle"})
+
+					query := mustBuildSelectQuery(t, dialect, test.scanTarget, test.query)
+
+					rows, err := db.QueryContext(ctx, query)
+					tt.AssertNoErr(t, err)
+					defer rows.Close()
+
+					tt.AssertEqual(t, rows.Next(), true)
+
+					err = scanRows(ctx, dialect, rows, test.scanTarget)
+					tt.AssertErrContains(t, err, test.expectErrToContain...)
+				})
+			}
+		})
+
 		t.Run("should report error for closed rows", func(t *testing.T) {
 			err := createTables(driver, connStr)
 			if err != nil {
@@ -3119,7 +3216,6 @@ func ScanRowsTest(
 			}
 
 			dialect := supportedDialects[driver]
-			ctx := context.TODO()
 			db, closer := newDBAdapter(t)
 			defer closer.Close()
 
@@ -3140,7 +3236,6 @@ func ScanRowsTest(
 			}
 
 			dialect := supportedDialects[driver]
-			ctx := context.TODO()
 			db, closer := newDBAdapter(t)
 			defer closer.Close()
 
@@ -3160,7 +3255,6 @@ func ScanRowsTest(
 			}
 
 			dialect := supportedDialects[driver]
-			ctx := context.TODO()
 			db, closer := newDBAdapter(t)
 			defer closer.Close()
 
@@ -3446,3 +3540,22 @@ func getUserPermissionsByUser(db DBAdapter, driver string, userID int) (results
 
 	return results, nil
 }
+
+func mustBuildSelectQuery(t *testing.T,
+	dialect Dialect,
+	record interface{},
+	query string,
+) string {
+	if strings.HasPrefix(query, "SELECT") {
+		return query
+	}
+
+	structType := reflect.TypeOf(record).Elem()
+	structInfo, err := structs.GetTagInfo(structType)
+	tt.AssertNoErr(t, err)
+
+	selectPrefix, err := buildSelectQuery(dialect, structType, structInfo, selectQueryCache[dialect.DriverName()])
+	tt.AssertNoErr(t, err)
+
+	return selectPrefix + query
+}