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