queen

Queen

Database migrations for Go.

Queen is a database migration library that lets you define migrations in code, not separate files. It supports both SQL and Go function migrations, with built-in testing helpers and a simple, idiomatic API.

Features

• Migrations in code - Define migrations as Go code, not separate .sql files
• Flexible syntax - Use SQL strings in code, Go functions, or mix both
• Testing helpers - Built-in support for testing your migrations
• Natural sorting - Smart version ordering: "1" < "2" < "10" < "100", "user_1" < "user_10"
• Flexible versioning - Use sequential numbers, prefixes, or any naming scheme
• Type-safe - Full Go type safety for programmatic migrations
• Multiple databases - PostgreSQL, MySQL, SQLite support with extensible driver interface
• Lock protection - Prevents concurrent migration runs
• Checksum validation - Detects when applied migrations have changed

Quick Start

Installation

PostgreSQL

go get github.com/honeynil/queen
go get github.com/honeynil/queen/drivers/postgres
go get github.com/jackc/pgx/v5/stdlib

MySQL

go get github.com/honeynil/queen
go get github.com/honeynil/queen/drivers/mysql
go get github.com/go-sql-driver/mysql

SQLite

go get github.com/honeynil/queen
go get github.com/honeynil/queen/drivers/sqlite
go get github.com/mattn/go-sqlite3

Basic Usage

PostgreSQL

package main

import (
    "context"
    "database/sql"
    "log"

    _ "github.com/jackc/pgx/v5/stdlib"

    "github.com/honeynil/queen"
    "github.com/honeynil/queen/drivers/postgres"
)

func main() {
    // Connect to database
    db, _ := sql.Open("pgx", "postgres://localhost/myapp?sslmode=disable")
    defer db.Close()

    // Create Queen instance
    driver := postgres.New(db)
    q := queen.New(driver)
    defer q.Close()

    // Register migrations
    q.MustAdd(queen.M{
        Version: "001",
        Name:    "create_users_table",
        UpSQL: `
            CREATE TABLE users (
                id SERIAL PRIMARY KEY,
                email VARCHAR(255) NOT NULL UNIQUE,
                created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
            )
        `,
        DownSQL: `DROP TABLE users`,
    })

    q.MustAdd(queen.M{
        Version: "002",
        Name:    "add_users_name",
        UpSQL:   `ALTER TABLE users ADD COLUMN name VARCHAR(255)`,
        DownSQL: `ALTER TABLE users DROP COLUMN name`,
    })

    // Apply all pending migrations
    ctx := context.Background()
    if err := q.Up(ctx); err != nil {
        log.Fatal(err)
    }

    log.Println("Migrations applied successfully!")
}

MySQL

package main

import (
    "context"
    "database/sql"
    "log"

    _ "github.com/go-sql-driver/mysql"

    "github.com/honeynil/queen"
    "github.com/honeynil/queen/drivers/mysql"
)

func main() {
    // Connect to MySQL (parseTime=true is required!)
    db, _ := sql.Open("mysql", "user:password@tcp(localhost:3306)/myapp?parseTime=true")
    defer db.Close()

    // Create Queen instance
    driver := mysql.New(db)
    q := queen.New(driver)
    defer q.Close()

    // Register migrations
    q.MustAdd(queen.M{
        Version: "001",
        Name:    "create_users_table",
        UpSQL: `
            CREATE TABLE users (
                id INT AUTO_INCREMENT PRIMARY KEY,
                email VARCHAR(255) NOT NULL UNIQUE,
                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
            ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
        `,
        DownSQL: `DROP TABLE users`,
    })

    q.MustAdd(queen.M{
        Version: "002",
        Name:    "add_users_name",
        UpSQL:   `ALTER TABLE users ADD COLUMN name VARCHAR(255)`,
        DownSQL: `ALTER TABLE users DROP COLUMN name`,
    })

    // Apply all pending migrations
    ctx := context.Background()
    if err := q.Up(ctx); err != nil {
        log.Fatal(err)
    }

    log.Println("Migrations applied successfully!")
}

SQLite

package main

import (
    "context"
    "database/sql"
    "log"

    _ "github.com/mattn/go-sqlite3"

    "github.com/honeynil/queen"
    "github.com/honeynil/queen/drivers/sqlite"
)

func main() {
    // Connect to SQLite (WAL mode recommended for better concurrency)
    db, _ := sql.Open("sqlite3", "myapp.db?_journal_mode=WAL&_foreign_keys=on")
    defer db.Close()

    // Create Queen instance
    driver := sqlite.New(db)
    q := queen.New(driver)
    defer q.Close()

    // Register migrations
    q.MustAdd(queen.M{
        Version: "001",
        Name:    "create_users_table",
        UpSQL: `
            CREATE TABLE users (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                email TEXT NOT NULL UNIQUE,
                created_at TEXT DEFAULT (datetime('now'))
            )
        `,
        DownSQL: `DROP TABLE users`,
    })

    q.MustAdd(queen.M{
        Version: "002",
        Name:    "add_users_name",
        UpSQL:   `ALTER TABLE users ADD COLUMN name TEXT`,
        DownSQL: `ALTER TABLE users DROP COLUMN name`,
    })

    // Apply all pending migrations
    ctx := context.Background()
    if err := q.Up(ctx); err != nil {
        log.Fatal(err)
    }

    log.Println("Migrations applied successfully!")
}

Usage Examples

Modular Migrations (Registry Pattern)

For large projects, organize migrations by domain:

// users/migrations.go
package users

func Register(q *queen.Queen) {
    q.MustAdd(queen.M{
        Version: "users_001",
        Name:    "create_users",
        UpSQL:   `CREATE TABLE users (...)`,
        DownSQL: `DROP TABLE users`,
    })
}

// posts/migrations.go
package posts

func Register(q *queen.Queen) {
    q.MustAdd(queen.M{
        Version: "posts_001",
        Name:    "create_posts",
        UpSQL:   `CREATE TABLE posts (...)`,
        DownSQL: `DROP TABLE posts`,
    })
}

// main.go
func main() {
    q := queen.New(driver)

    users.Register(q)
    posts.Register(q)

    q.Up(ctx)
}

Go Function Migrations

For complex migrations that need programmatic logic:

q.MustAdd(queen.M{
    Version:        "003",
    Name:           "normalize_emails",
    ManualChecksum: "v1", // Important: track function changes!
    UpFunc: func(ctx context.Context, tx *sql.Tx) error {
        // Fetch users
        rows, err := tx.QueryContext(ctx, "SELECT id, email FROM users")
        if err != nil {
            return err
        }
        defer rows.Close()

        // Process each user
        for rows.Next() {
            var id int
            var email string
            if err := rows.Scan(&id, &email); err != nil {
                return err
            }

            // Normalize email
            normalized := strings.ToLower(strings.TrimSpace(email))

            _, err = tx.ExecContext(ctx,
                "UPDATE users SET email = $1 WHERE id = $2",
                normalized, id)
            if err != nil {
                return err
            }
        }

        return rows.Err()
    },
    DownFunc: func(ctx context.Context, tx *sql.Tx) error {
        // Rollback logic (if possible)
        return nil
    },
})

Testing Migrations

Queen makes it easy to test your migrations:

func TestMigrations(t *testing.T) {
    // Setup test database
    db := setupTestDB(t)
    driver := postgres.New(db)

    // Create test instance (auto-cleanup on test end)
    q := queen.NewTest(t, driver)

    // Register migrations
    q.MustAdd(queen.M{
        Version: "001",
        Name:    "create_users",
        UpSQL:   `CREATE TABLE users (id INT)`,
        DownSQL: `DROP TABLE users`,
    })

    // Test both up and down migrations
    q.TestUpDown()
}

Migration Operations

// Apply all pending migrations
q.Up(ctx)

// Apply next N migrations
q.UpSteps(ctx, 3)

// Rollback last migration
q.Down(ctx, 1)

// Rollback last N migrations
q.Down(ctx, 3)

// Rollback all migrations
q.Reset(ctx)

// Get migration status
statuses, _ := q.Status(ctx)
for _, s := range statuses {
    fmt.Printf("%s: %s (%s)\n", s.Version, s.Name, s.Status)
}

// Validate migrations
if err := q.Validate(ctx); err != nil {
    log.Fatal(err)
}

Philosophy

Queen follows the principle: migrations are code, not files. This approach enables:

• Type safety and IDE support
• Easier testing and refactoring
• No file organization overhead
• Full programmatic control when needed

Queen is designed for developers who want clean, testable migrations without the ceremony.

Configuration

config := &queen.Config{
    TableName:   "custom_migrations", // Default: "queen_migrations"
    LockTimeout: 30 * time.Minute,    // Default: 30 minutes
    SkipLock:    false,               // Default: false (recommended)
}

q := queen.NewWithConfig(driver, config)

API Documentation

See pkg.go.dev for complete API documentation.

Key Types

Migration / M

type Migration struct {
    Version        string        // Unique version identifier
    Name           string        // Human-readable name
    UpSQL          string        // SQL to apply migration
    DownSQL        string        // SQL to rollback migration
    UpFunc         MigrationFunc // Go function to apply
    DownFunc       MigrationFunc // Go function to rollback
    ManualChecksum string        // Manual checksum for Go functions
}

type M = Migration // Convenient alias

Queen

type Queen struct { /* ... */ }

func New(driver Driver) *Queen
func NewWithConfig(driver Driver, config *Config) *Queen
func NewTest(t *testing.T, driver Driver) *TestHelper

func (q *Queen) Add(m M) error
func (q *Queen) MustAdd(m M)
func (q *Queen) Up(ctx context.Context) error
func (q *Queen) UpSteps(ctx context.Context, n int) error
func (q *Queen) Down(ctx context.Context, n int) error
func (q *Queen) Reset(ctx context.Context) error
func (q *Queen) Status(ctx context.Context) ([]MigrationStatus, error)
func (q *Queen) Validate(ctx context.Context) error
func (q *Queen) Close() error

Supported Databases

See the drivers directory for database-specific documentation and examples.

License

MIT License - see LICENSE for details.

Author

Created by honeynil