fix: nested scan (#6136)

callbacks/row.go

@@ -11,8 +11,7 @@ func RowQuery(db *gorm.DB) {
 			return
 		}
 
-		if isRows, ok := db.Get("rows"); ok && isRows.(bool) {
-			db.Statement.Settings.Delete("rows")
+		if isRows := db.PopQueryType(); isRows {
 			db.Statement.Dest, db.Error = db.Statement.ConnPool.QueryContext(db.Statement.Context, db.Statement.SQL.String(), db.Statement.Vars...)
 		} else {
 			db.Statement.Dest = db.Statement.ConnPool.QueryRowContext(db.Statement.Context, db.Statement.SQL.String(), db.Statement.Vars...)

finisher_api.go

@@ -499,7 +499,7 @@ func (db *DB) Count(count *int64) (tx *DB) {
 }
 
 func (db *DB) Row() *sql.Row {
-	tx := db.getInstance().Set("rows", false)
+	tx := db.getInstance().PushQueryType(false)
 	tx = tx.callbacks.Row().Execute(tx)
 	row, ok := tx.Statement.Dest.(*sql.Row)
 	if !ok && tx.DryRun {
@@ -509,7 +509,7 @@ func (db *DB) Row() *sql.Row {
 }
 
 func (db *DB) Rows() (*sql.Rows, error) {
-	tx := db.getInstance().Set("rows", true)
+	tx := db.getInstance().PushQueryType(true)
 	tx = tx.callbacks.Row().Execute(tx)
 	rows, ok := tx.Statement.Dest.(*sql.Rows)
 	if !ok && tx.DryRun && tx.Error == nil {

gorm.go

@@ -340,6 +340,22 @@ func (db *DB) InstanceGet(key string) (interface{}, bool) {
 	return db.Statement.Settings.Load(fmt.Sprintf("%p", db.Statement) + key)
 }
 
+func (db *DB) PushQueryType(rows bool) *DB {
+	tx := db.getInstance()
+	tx.Statement.queryTypes = append(tx.Statement.queryTypes, rows)
+	return tx
+}
+
+func (db *DB) PopQueryType() bool {
+	length := len(db.Statement.queryTypes)
+	if length == 0 {
+		return false
+	}
+	value := db.Statement.queryTypes[length-1]
+	db.Statement.queryTypes = db.Statement.queryTypes[:length-1]
+	return value
+}
+
 // Callback returns callback manager
 func (db *DB) Callback() *callbacks {
 	return db.callbacks

statement.go

@@ -46,6 +46,7 @@ type Statement struct {
 	attrs                []interface{}
 	assigns              []interface{}
 	scopes               []func(*DB) *DB
+	queryTypes           []bool
 }
 
 type join struct {
@@ -543,6 +544,11 @@ func (stmt *Statement) clone() *Statement {
 		copy(newStmt.scopes, stmt.scopes)
 	}
 
+	if len(stmt.queryTypes) > 0 {
+		newStmt.queryTypes = make([]bool, len(stmt.queryTypes))
+		copy(newStmt.queryTypes, stmt.queryTypes)
+	}
+
 	stmt.Settings.Range(func(k, v interface{}) bool {
 		newStmt.Settings.Store(k, v)
 		return true

tests/scopes_test.go

@@ -71,4 +71,15 @@ func TestScopes(t *testing.T) {
 	if err := DB.Scopes(userTable).Select("max(id)").Scan(&maxId).Error; err != nil {
 		t.Errorf("select max(id)")
 	}
+
+	var user User
+	if err := DB.Scopes(func(db *gorm.DB) *gorm.DB {
+		var maxID int64
+		if err := db.Raw("select max(id) from users").Scan(&maxID).Error; err != nil {
+			return db
+		}
+		return db.Raw("select * from users where id = ?", maxID)
+	}).Scan(&user).Error; err != nil {
+		t.Errorf("failed to find user, got err: %v", err)
+	}
 }