add transactions

internal/postgres/movie.go

@@ -32,10 +32,16 @@ func (s *MovieService) GetMovie(ctx context.Context, id int64) (*greenlight.Movi
 	ctx, cancel := context.WithTimeout(ctx, s.db.opts.queryTimeout)
 	defer cancel()
 
+	tx, err := s.db.db.BeginTx(ctx, nil)
+	if err != nil {
+		return nil, fmt.Errorf("%s: %w", op, err)
+	}
+	defer tx.Rollback()
+
 	query := `SELECT id, title, release_date, runtime, genres, version FROM movies WHERE id = $1`
 	args := []any{id}
 	var m greenlight.Movie
-	if err := s.db.db.QueryRowContext(ctx, query, args...).Scan(&m.ID, &m.Title, &m.ReleaseDate, &m.Runtime, pq.Array(&m.Genres), &m.Version); err != nil {
+	if err := tx.QueryRowContext(ctx, query, args...).Scan(&m.ID, &m.Title, &m.ReleaseDate, &m.Runtime, pq.Array(&m.Genres), &m.Version); err != nil {
 		switch {
 		case errors.Is(err, sql.ErrNoRows):
 			return nil, greenlight.NewNotFoundError("Movie with id=%d is not found.", id)
@@ -44,6 +50,9 @@ func (s *MovieService) GetMovie(ctx context.Context, id int64) (*greenlight.Movi
 		}
 	}
 
+	if err := tx.Commit(); err != nil {
+		return nil, fmt.Errorf("%s: %w", op, err)
+	}
 	return &m, nil
 }
 
@@ -53,6 +62,12 @@ func (s *MovieService) GetMovies(ctx context.Context, filter greenlight.MovieFil
 	ctx, cancel := context.WithTimeout(ctx, s.db.opts.queryTimeout)
 	defer cancel()
 
+	tx, err := s.db.db.BeginTx(ctx, nil)
+	if err != nil {
+		return nil, fmt.Errorf("%s: %w", op, err)
+	}
+	defer tx.Rollback()
+
 	sortCol, sortDir := filter.Sort, "ASC"
 	if v, ok := strings.CutPrefix(sortCol, "-"); ok {
 		sortCol = v
@@ -65,7 +80,7 @@ func (s *MovieService) GetMovies(ctx context.Context, filter greenlight.MovieFil
 		WHERE (LOWER(title) = LOWER($1) OR $1 = '') AND (genres @> $2 OR $2 = '{}')
 		ORDER BY %s %s, id ASC
 		LIMIT $3 OFFSET $4`, sortCol, sortDir)
-	rs, err := s.db.db.QueryContext(ctx, query, filter.Title, pq.Array(filter.Genres), filter.PageSize, (filter.Page-1)*filter.PageSize)
+	rs, err := tx.QueryContext(ctx, query, filter.Title, pq.Array(filter.Genres), filter.PageSize, (filter.Page-1)*filter.PageSize)
 	if err != nil {
 		return nil, fmt.Errorf("%s: %w", op, err)
 	}
@@ -83,6 +98,9 @@ func (s *MovieService) GetMovies(ctx context.Context, filter greenlight.MovieFil
 		return nil, fmt.Errorf("%s: %w", op, err)
 	}
 
+	if err := tx.Commit(); err != nil {
+		return nil, fmt.Errorf("%s: %w", op, err)
+	}
 	return movies, nil
 }
 
@@ -92,16 +110,26 @@ func (s *MovieService) UpdateMovie(ctx context.Context, m *greenlight.Movie) err
 	ctx, cancel := context.WithTimeout(ctx, s.db.opts.queryTimeout)
 	defer cancel()
 
+	tx, err := s.db.db.BeginTx(ctx, nil)
+	if err != nil {
+		return fmt.Errorf("%s: %w", op, err)
+	}
+	defer tx.Rollback()
+
 	query := `UPDATE movies SET (title, release_date, runtime, genres, version) = ($1, $2, $3, $4, version+1) WHERE id = $5 AND version = $6 RETURNING version`
 	args := []any{m.Title, m.ReleaseDate, m.Runtime, pq.Array(m.Genres), m.ID, m.Version}
-	if err := s.db.db.QueryRowContext(ctx, query, args...).Scan(&m.Version); err != nil {
+	if err := tx.QueryRowContext(ctx, query, args...).Scan(&m.Version); err != nil {
 		switch {
 		case errors.Is(err, sql.ErrNoRows):
 			return greenlight.NewConflictError("Conflicting change for the movie with id=%d", m.ID)
 		default:
 			return fmt.Errorf("%s: movie with id=%d: %w", op, m.ID, err)
 		}
 	}
+
+	if err := tx.Commit(); err != nil {
+		return fmt.Errorf("%s: %w", op, err)
+	}
 	return nil
 }
 
@@ -111,9 +139,15 @@ func (s *MovieService) DeleteMovie(ctx context.Context, id int64) error {
 	ctx, cancel := context.WithTimeout(ctx, s.db.opts.queryTimeout)
 	defer cancel()
 
+	tx, err := s.db.db.BeginTx(ctx, nil)
+	if err != nil {
+		return fmt.Errorf("%s: %w", op, err)
+	}
+	defer tx.Rollback()
+
 	query := `DELETE FROM movies where id = $1`
 	args := []any{id}
-	rs, err := s.db.db.ExecContext(ctx, query, args...)
+	rs, err := tx.ExecContext(ctx, query, args...)
 	if err != nil {
 		return fmt.Errorf("%s: movie with id=%d: %w", op, id, err)
 	}
@@ -126,6 +160,9 @@ func (s *MovieService) DeleteMovie(ctx context.Context, id int64) error {
 		return greenlight.NewNotFoundError("Movie with id=%d is not found.", id)
 	}
 
+	if err := tx.Commit(); err != nil {
+		return fmt.Errorf("%s: %w", op, err)
+	}
 	return nil
 }
 
@@ -135,9 +172,19 @@ func (s *MovieService) CreateMovie(ctx context.Context, m *greenlight.Movie) err
 	ctx, cancel := context.WithTimeout(ctx, s.db.opts.queryTimeout)
 	defer cancel()
 
+	tx, err := s.db.db.BeginTx(ctx, nil)
+	if err != nil {
+		return fmt.Errorf("%s: %w", op, err)
+	}
+	defer tx.Rollback()
+
 	query := `INSERT INTO movies (title, release_date, runtime, genres) VALUES ($1, $2, $3, $4) RETURNING id, version`
 	args := []any{m.Title, m.ReleaseDate, m.Runtime, pq.Array(m.Genres)}
-	if err := s.db.db.QueryRowContext(ctx, query, args...).Scan(&m.ID, &m.Version); err != nil {
+	if err := tx.QueryRowContext(ctx, query, args...).Scan(&m.ID, &m.Version); err != nil {
+		return fmt.Errorf("%s: %w", op, err)
+	}
+
+	if err := tx.Commit(); err != nil {
 		return fmt.Errorf("%s: %w", op, err)
 	}
 	return nil