package asset import ( "bytes" "database/sql" "errors" "fmt" "io" "code.betamike.com/mediocregopher/mediocre-blog/src/post" ) var ( // ErrNotFound is used to indicate an Asset could not be found in the // Store. ErrNotFound = errors.New("asset not found") ) // Store implements the storage and retrieval of binary assets, which are // intended to be used by posts (e.g. images). type Store interface { // Set sets the id to the contents of the given io.Reader. Set(id string, from io.Reader) error // Get writes the id's body to the given io.Writer, or returns // ErrNotFound. Get(id string, into io.Writer) error // Delete's the body stored for the id, if any. Delete(id string) error // List returns all ids which are currently stored. List() ([]string, error) } type store struct { db *post.SQLDB } // NewStore initializes a new Store using an existing SQLDB. func NewStore(db *post.SQLDB) Store { return &store{ db: db, } } func (s *store) Set(id string, from io.Reader) error { body, err := io.ReadAll(from) if err != nil { return fmt.Errorf("reading body fully into memory: %w", err) } _, err = s.db.Exec( `INSERT INTO assets (id, body) VALUES (?, ?) ON CONFLICT (id) DO UPDATE SET body=excluded.body`, id, body, ) if err != nil { return fmt.Errorf("inserting into assets: %w", err) } return nil } func (s *store) Get(id string, into io.Writer) error { var body []byte err := s.db.QueryRow(`SELECT body FROM assets WHERE id = ?`, id).Scan(&body) if errors.Is(err, sql.ErrNoRows) { return ErrNotFound } else if err != nil { return fmt.Errorf("selecting from assets: %w", err) } if _, err := io.Copy(into, bytes.NewReader(body)); err != nil { return fmt.Errorf("writing body to io.Writer: %w", err) } return nil } func (s *store) Delete(id string) error { _, err := s.db.Exec(`DELETE FROM assets WHERE id = ?`, id) return err } func (s *store) List() ([]string, error) { rows, err := s.db.Query(`SELECT id FROM assets ORDER BY id ASC`) if err != nil { return nil, fmt.Errorf("querying: %w", err) } defer rows.Close() var ids []string for rows.Next() { var id string if err := rows.Scan(&id); err != nil { return nil, fmt.Errorf("scanning row: %w", err) } ids = append(ids, id) } return ids, nil }