initial planning
This commit is contained in:
79
database/memory.go
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79
database/memory.go
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@@ -0,0 +1,79 @@
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package database
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import (
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"context"
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"fmt"
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"sync"
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"git.yetaga.in/alazyreader/library/book"
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)
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type Memory struct {
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lock sync.Mutex
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shelf []book.Book
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}
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func (m *Memory) GetAllBooks(_ context.Context) ([]book.Book, error) {
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m.lock.Lock()
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defer m.lock.Unlock()
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if m.shelf == nil {
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m.shelf = []book.Book{}
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}
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return m.shelf, nil
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}
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func (m *Memory) AddBook(_ context.Context, b *book.Book) error {
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m.lock.Lock()
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defer m.lock.Unlock()
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if m.shelf == nil {
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m.shelf = []book.Book{}
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}
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m.shelf = append(m.shelf, *b)
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return nil
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}
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func (m *Memory) UpdateBook(_ context.Context, old, new *book.Book) error {
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m.lock.Lock()
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defer m.lock.Unlock()
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if m.shelf == nil {
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m.shelf = []book.Book{}
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return fmt.Errorf("book does not exist")
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}
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if old.ID != new.ID {
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return fmt.Errorf("cannot change book ID")
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}
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for i := range m.shelf {
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if m.shelf[i].ID == old.ID {
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m.shelf[i] = *new
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return nil
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}
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}
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return fmt.Errorf("book does not exist")
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}
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func (m *Memory) DeleteBook(_ context.Context, b *book.Book) error {
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m.lock.Lock()
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defer m.lock.Unlock()
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if m.shelf == nil {
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m.shelf = []book.Book{}
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return fmt.Errorf("book does not exist")
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}
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for i := range m.shelf {
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if m.shelf[i].ID == b.ID {
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// reorder slice to remove book quickly
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m.shelf[i] = m.shelf[len(m.shelf)-1]
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m.shelf = m.shelf[:len(m.shelf)-1]
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return nil
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}
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}
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return fmt.Errorf("book does not exist")
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}
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0
database/migrations/mysql/01-init.sql
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0
database/migrations/mysql/01-init.sql
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211
database/mysql.go
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211
database/mysql.go
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@@ -0,0 +1,211 @@
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package database
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import (
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"context"
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"database/sql"
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"embed"
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"fmt"
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"io/fs"
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"strconv"
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"strings"
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"time"
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"git.yetaga.in/alazyreader/library/book"
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_ "github.com/go-sql-driver/mysql"
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)
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//go:embed migrations/mysql
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var migrationsFS embed.FS
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type migration struct {
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id int
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name string
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content []byte
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}
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type MySQL struct {
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connection *sql.DB
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versionTable string
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migrationsDirectory string
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}
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func NewMySQLConnection(user, pass, host, port, db string) (*MySQL, error) {
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dsn := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s", user, pass, host, port, db) // what a strange syntax
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connection, err := sql.Open("mysql", dsn)
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if err != nil {
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return nil, err
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}
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return &MySQL{
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connection: connection,
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versionTable: "migrations",
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migrationsDirectory: "/migrations/mysql",
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}, nil
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}
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func (m *MySQL) PrepareDatabase(ctx context.Context) error {
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if m.connection == nil || m.migrationsDirectory == "" || m.versionTable == "" {
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return fmt.Errorf("uninitialized mysql client")
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}
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tablecheck := `SELECT count(*) AS count
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FROM information_schema.TABLES
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WHERE TABLE_NAME = '` + m.versionTable + `'
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AND TABLE_SCHEMA in (SELECT DATABASE());`
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tableschema := `CREATE TABLE ` + m.versionTable + `(
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id INT NOT NULL,
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name VARCHAR(100) NOT NULL,
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datetime DATE,
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PRIMARY KEY (id))`
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var versionTableExists int
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m.connection.QueryRowContext(ctx, tablecheck).Scan(&versionTableExists)
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if versionTableExists != 0 {
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return nil
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}
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_, err := m.connection.ExecContext(ctx, tableschema)
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return err
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}
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func (m *MySQL) GetLatestMigration(ctx context.Context) (int, error) {
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if m.connection == nil || m.migrationsDirectory == "" || m.versionTable == "" {
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return 0, fmt.Errorf("uninitialized mysql client")
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}
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var latestMigration int
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err := m.connection.QueryRowContext(ctx, "SELECT MAX(id) FROM "+m.versionTable).Scan(&latestMigration)
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return latestMigration, err
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}
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func (m *MySQL) RunMigrations(ctx context.Context) (int, error) {
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if m.connection == nil || m.migrationsDirectory == "" || m.versionTable == "" {
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return 0, fmt.Errorf("uninitialized mysql client")
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}
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var migrations map[int]migration
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dir, err := migrationsFS.ReadDir(m.migrationsDirectory)
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if err != nil {
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return 0, nil
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}
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for f := range dir {
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if dir[f].Type().IsRegular() {
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mig := migration{}
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id, name, err := parseMigrationFileName(dir[f].Name())
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if err != nil {
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return 0, err
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}
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mig.id, mig.name = id, name
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mig.content, err = fs.ReadFile(migrationsFS, m.migrationsDirectory+"/"+dir[f].Name())
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migrations[mig.id] = mig
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}
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}
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latestMigrationRan, err := m.GetLatestMigration(ctx)
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if err != nil {
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return 0, err
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}
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// exit if nothing to do (that is, there's no greater migration ID)
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if _, ok := migrations[latestMigrationRan+1]; !ok {
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return latestMigrationRan, nil
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}
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// loop over and apply migrations if required
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tx, err := m.connection.BeginTx(ctx, nil)
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if err != nil {
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return latestMigrationRan, err
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}
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for migrationsToRun := true; migrationsToRun; _, migrationsToRun = migrations[latestMigrationRan+1] {
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mig := migrations[latestMigrationRan+1]
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_, err := tx.ExecContext(ctx, string(mig.content))
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if err != nil {
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nestederr := tx.Rollback()
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if nestederr != nil {
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return latestMigrationRan, nestederr
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}
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return latestMigrationRan, err
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}
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_, err = tx.ExecContext(ctx, "INSERT INTO "+m.versionTable+" (id, name, datetime) VALUES (?, ?, ?)", mig.id, mig.name, time.Now())
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if err != nil {
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nestederr := tx.Rollback()
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if nestederr != nil {
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return latestMigrationRan, nestederr
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}
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return latestMigrationRan, err
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}
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latestMigrationRan = latestMigrationRan + 1
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}
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err = tx.Commit()
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return latestMigrationRan, err
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}
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func (m *MySQL) GetAllBooks(ctx context.Context) ([]book.Book, error) {
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if m.connection == nil {
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return nil, fmt.Errorf("uninitialized mysql client")
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}
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books := []book.Book{}
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rows, err := m.connection.QueryContext(ctx, "SELECT id, title FROM books")
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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for rows.Next() {
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b := book.Book{}
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err := rows.Scan(&b.ID, &b.Title)
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if err != nil {
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return nil, err
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}
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books = append(books, b)
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}
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return books, nil
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}
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func (m *MySQL) AddBook(ctx context.Context, b *book.Book) error {
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if m.connection == nil {
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return fmt.Errorf("uninitialized mysql client")
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}
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res, err := m.connection.ExecContext(ctx, "INSERT INTO books (title) VALUES (?)", b.Title)
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if err != nil {
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return err
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}
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i, err := res.RowsAffected()
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if err != nil {
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return err
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}
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if i != 1 {
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return fmt.Errorf("unexpectedly updated more than one row: %d", i)
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}
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return nil
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}
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func (m *MySQL) UpdateBook(ctx context.Context, old, new *book.Book) error {
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if m.connection == nil {
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return fmt.Errorf("uninitialized mysql client")
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}
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res, err := m.connection.ExecContext(ctx, "UPDATE books SET title=? WHERE id=?", new.Title, old.ID)
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if err != nil {
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return err
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}
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i, err := res.RowsAffected()
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if err != nil {
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return err
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}
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if i != 1 {
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return fmt.Errorf("unexpectedly updated more than one row: %d", i)
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}
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return nil
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}
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func parseMigrationFileName(filename string) (int, string, error) {
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sp := strings.SplitN(filename, "-", 2)
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i, err := strconv.Atoi(sp[0])
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if err != nil {
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return 0, "", err
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}
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tr := strings.TrimSuffix(sp[1], ".sql")
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return i, tr, nil
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}
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