Rene Nochebuena
9191751d57
Patch of the coordinated framework release: einherjar modules move to v1.1.0 in lockstep, so db-mysql is bumped alongside the rest. - go.mod: contracts, core -> v1.1.0 (via go get + go mod tidy) No code or API changes. ModuleVersion() reports v1.1.0 automatically from build info once tagged. Badge bumped to v1.1.0. Reviewed-on: #1 Co-authored-by: Rene Nochebuena Guerrero <rene@nochebuena.dev> Co-committed-by: Rene Nochebuena Guerrero <rene@nochebuena.dev>
140 lines
4.3 KiB
Markdown
140 lines
4.3 KiB
Markdown
# einherjar/db-mysql
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[](https://code.nochebuena.dev/einherjar/db-mysql)
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[](LICENSE)
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[](https://go.dev)
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[]()
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> A warrior's deeds are committed to stone so that what they built survives the builder.
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`code.nochebuena.dev/einherjar/db-mysql` is the MySQL/MariaDB database component of the Einherjar framework. It wraps `database/sql` with `go-sql-driver/mysql` behind a lifecycle-aware `Component`, exposes a uniform `Executor` interface for queries and transactions, and provides a `UnitOfWork` that injects the active transaction into context — so repositories never need to know whether they are inside a transaction or not.
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---
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## Usage
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### Setup
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```go
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import dbmysql "code.nochebuena.dev/einherjar/db-mysql"
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db := dbmysql.New(logger, dbmysql.DefaultConfig())
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launcher.Append(db) // OnInit opens pool; OnStop closes it
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health.Register(db) // PING health check; LevelCritical
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```
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### Querying
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```go
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// GetExecutor returns the pool when called outside a UnitOfWork.
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rows, err := db.GetExecutor(ctx).QueryContext(ctx, "SELECT id, name FROM users WHERE active = ?", true)
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defer rows.Close()
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var name string
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err := db.GetExecutor(ctx).QueryRowContext(ctx, "SELECT name FROM users WHERE id = ?", id).Scan(&name)
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```
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### Manual transaction
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```go
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tx, err := db.Begin(ctx)
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if err != nil {
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return err
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}
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defer tx.Rollback()
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_, err = tx.ExecContext(ctx, "UPDATE accounts SET balance = balance - ? WHERE id = ?", amount, fromID)
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if err != nil {
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return err
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}
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return tx.Commit()
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```
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`BeginTx` is available when you need explicit isolation level control:
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```go
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tx, err := db.BeginTx(ctx, &sql.TxOptions{Isolation: sql.LevelSerializable})
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```
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### Unit of work (recommended)
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`UnitOfWork` wraps the transaction in context so every call to `GetExecutor` inside `uow.Do` automatically returns the active transaction. Repositories require no changes.
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```go
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uow := dbmysql.NewUnitOfWork(logger, db)
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err := uow.Do(ctx, func(ctx context.Context) error {
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_, err := db.GetExecutor(ctx).ExecContext(ctx, "INSERT INTO orders (...) VALUES (...)", ...)
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return err
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})
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```
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If the function returns an error, the transaction is rolled back. If it returns nil, the transaction is committed.
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### Error handling
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```go
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if err := db.HandleError(someErr); err != nil {
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// MySQL error numbers mapped to xerrors:
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// 1062 ER_DUP_ENTRY → ErrAlreadyExists
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// 1216 ER_NO_REFERENCED_ROW → ErrPreconditionFailed
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// 1048 ER_BAD_NULL_ERROR → ErrInvalidInput
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// context.Canceled → ErrCancelled
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// context.DeadlineExceeded → ErrDeadlineExceeded
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}
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```
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`HandleError` is also available as a package-level function: `dbmysql.HandleError(err)`.
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---
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## Environment variables
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| Variable | Required | Default | Description |
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|---|---|---|---|
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| `EINHERJAR_MYSQL_HOST` | Yes | — | MySQL host |
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| `EINHERJAR_MYSQL_PORT` | No | `3306` | Listen port |
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| `EINHERJAR_MYSQL_USER` | Yes | — | Database user |
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| `EINHERJAR_MYSQL_PASSWORD` | Yes | — | Database password |
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| `EINHERJAR_MYSQL_NAME` | Yes | — | Database name |
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| `EINHERJAR_MYSQL_MAX_CONNS` | No | `5` | Maximum open connections |
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| `EINHERJAR_MYSQL_MIN_CONNS` | No | `2` | Minimum idle connections |
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| `EINHERJAR_MYSQL_MAX_CONN_LIFETIME` | No | `1h` | Maximum connection lifetime |
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| `EINHERJAR_MYSQL_MAX_CONN_IDLE_TIME` | No | `30m` | Maximum idle time before connection is closed |
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| `EINHERJAR_MYSQL_CHARSET` | No | `utf8mb4` | Connection charset |
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| `EINHERJAR_MYSQL_LOC` | No | `UTC` | Timezone location |
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| `EINHERJAR_MYSQL_PARSE_TIME` | No | `true` | Parse `DATE`/`DATETIME` as `time.Time` |
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> **Note:** Set collation at the schema level (DDL), not in the DSN. MariaDB 11.4+ collation names exceed the 1-byte handshake limit in `go-sql-driver`.
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---
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## Dependency graph
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```
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contracts (zero dependencies)
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↑
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core
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↑
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db-mysql (contracts, core, go-sql-driver/mysql)
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↑
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your app
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```
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---
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## Verification
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```bash
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cd db-mysql/
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go build ./...
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go vet ./...
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go test ./...
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gofmt -l .
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```
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---
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> *The hall is built before the warriors arrive.*
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> *That is the only guarantee worth making.*
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