getfile.go

type GetFileResponse struct {
	FileBytes   []byte
	ContentType string
}

// GetFile returns a file from the s3 bucket
func (s Service) GetFile(filename string) (GetFileResponse, error) {
	input := &s3.GetObjectInput{
		Bucket: aws.String(s.Bucket),
		Key:    aws.String(filename),
	}

	result, err := s.S3.GetObject(input)
	if err != nil {
		if aswErr, ok := err.(awserr.Error); ok {
			switch aswErr.Code() {
			case s3.ErrCodeNoSuchKey:
				return GetFileResponse{}, fmt.Errorf("s3.GetFile: file does not exists")
			default:
				return GetFileResponse{}, fmt.Errorf("s3.GetFile: %w", err)
			}
		}

		return GetFileResponse{}, fmt.Errorf("s3.GetFile: %w", err)
	}
	defer result.Body.Close()

	// we need the file content type and bytes to return the file with echo (web framework)
	m := GetFileResponse{}
	fileBytes, err := io.ReadAll(result.Body)
	if err != nil {
		return GetFileResponse{}, fmt.Errorf("s3.GetFile.io.ReadAll(): %w", err)
	}
	m.FileBytes = fileBytes

	if result.ContentType != nil {
		m.ContentType = *result.ContentType
	}

	return m, nil
}