58 lines
2.0 KiB
Go
58 lines
2.0 KiB
Go
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// Package mysql provides a database/sql-backed MySQL client with lifecycle
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// management, health checks, and unit-of-work transaction support for
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// Einherjar applications.
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//
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// # Overview
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//
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// [New] returns a [Component] that manages a *sql.DB connection pool,
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// satisfies the [lifecycle.Component] lifecycle hooks (OnInit, OnStart, OnStop),
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// and implements [observability.Checkable] with critical priority.
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//
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// [NewUnitOfWork] wraps multiple repository operations in a single transaction
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// via context injection — no transaction object is passed between functions.
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//
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// # Lifecycle Registration
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//
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// db := mysql.New(logger, cfg)
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// launcher.Register(db)
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// health.Register(db)
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//
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// # Querying
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//
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// Repository code receives a [Provider] or [Executor] and calls [Provider.GetExecutor]
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// to obtain the active transaction (if inside a [UnitOfWork]) or the pool:
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//
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// exec := db.GetExecutor(ctx)
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// row := exec.QueryRowContext(ctx, "SELECT id FROM users WHERE email = ?", email)
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// if err := row.Scan(&id); err != nil {
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// return db.HandleError(err)
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// }
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//
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// # Unit of Work
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//
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// [NewUnitOfWork] wraps operations in a single transaction. The transaction is
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// injected into the context; [Provider.GetExecutor] returns it automatically.
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//
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// uow := mysql.NewUnitOfWork(logger, db)
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// err := uow.Do(ctx, func(ctx context.Context) error {
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// exec := db.GetExecutor(ctx) // returns active Tx
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// _, err := exec.ExecContext(ctx, "INSERT INTO orders ...")
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// return err
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// })
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//
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// # Error Handling
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//
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// [HandleError] translates MySQL driver errors into typed [xerrors] values.
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// Call it at every point where a driver error is first observed:
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//
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// if err := row.Scan(&out); err != nil {
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// return db.HandleError(err)
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// }
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//
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// Mapped codes:
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// - 1062 (ER_DUP_ENTRY) → ErrAlreadyExists
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// - 1216, 1217, 1451, 1452 (FK errors) → ErrInvalidInput
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// - sql.ErrNoRows → ErrNotFound
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// - all others → ErrInternal
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package mysql
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