Add RollbackUnlessCommitted() (#2126)

main.go

@@ -542,6 +542,23 @@ func (s *DB) Rollback() *DB {
 	return s
 }
 
+// RollbackUnlessCommitted rollback a transaction if it has not yet been
+// committed.
+func (s *DB) RollbackUnlessCommitted() *DB {
+	var emptySQLTx *sql.Tx
+	if db, ok := s.db.(sqlTx); ok && db != nil && db != emptySQLTx {
+		err := db.Rollback()
+		// Ignore the error indicating that the transaction has already
+		// been committed.
+		if err != sql.ErrTxDone {
+			s.AddError(err)
+		}
+	} else {
+		s.AddError(ErrInvalidTransaction)
+	}
+	return s
+}
+
 // NewRecord check if value's primary key is blank
 func (s *DB) NewRecord(value interface{}) bool {
 	return s.NewScope(value).PrimaryKeyZero()

main_test.go

@@ -419,6 +419,40 @@ func TestTransaction(t *testing.T) {
 	if err := DB.First(&User{}, "name = ?", "transcation-2").Error; err != nil {
 		t.Errorf("Should be able to find committed record")
 	}
+
+	tx3 := DB.Begin()
+	u3 := User{Name: "transcation-3"}
+	if err := tx3.Save(&u3).Error; err != nil {
+		t.Errorf("No error should raise")
+	}
+
+	if err := tx3.First(&User{}, "name = ?", "transcation-3").Error; err != nil {
+		t.Errorf("Should find saved record")
+	}
+
+	tx3.RollbackUnlessCommitted()
+
+	if err := tx.First(&User{}, "name = ?", "transcation").Error; err == nil {
+		t.Errorf("Should not find record after rollback")
+	}
+
+	tx4 := DB.Begin()
+	u4 := User{Name: "transcation-4"}
+	if err := tx4.Save(&u4).Error; err != nil {
+		t.Errorf("No error should raise")
+	}
+
+	if err := tx4.First(&User{}, "name = ?", "transcation-4").Error; err != nil {
+		t.Errorf("Should find saved record")
+	}
+
+	tx4.Commit()
+
+	tx4.RollbackUnlessCommitted()
+
+	if err := DB.First(&User{}, "name = ?", "transcation-4").Error; err != nil {
+		t.Errorf("Should be able to find committed record")
+	}
 }
 
 func TestTransaction_NoErrorOnRollbackAfterCommit(t *testing.T) {