Very Simple Migration Tool

This package don't supports rollback, squahs and complex features available in other migration packages. It handles only PostgreSQL and uses SEQUENCE feature to store migration number.

Install

We recommend use dep to install package:

$ dep ensure -add github.com/gigovich/vsmt

or simple go get

$ go get github.com/gigovich/vsmt

Usage

Migration function uses two arguments scheme and migrations. First argument should contain actual state of schema. Queries from this list always used for database initialization. Second argument contains migration queries.

Don't forget update scheme when add queries to migrations argument. You can call migration function any time on empty/non empty databases and it will guaratiee you actual state of scheme.

Besides use plain queries inside migrations argument, you can use MigrationFunc which help you do complex queries where you need Golang code fox processing data or queries.

package main

import (
	"database/sql"
	"fmt"

	"github.com/gigovich/vsmt"
	_ "github.com/lib/pq"
)

// schema should contain actual state of database, when you create migration comman you also should update
// this records
var schema = []string{
	`CREATE TABLE state (
		id serial PRIMARY KEY,
		name text,
		is_active bool
	)`,
	`CREATE TABLE job (
		id serial PRIMARY KEY,
		state_id int REFERENCES state(id),
		title text
	)`,
}

// migrations queries list, when you add query here don't forget modify schema according this query
var migrations = []interface{}{
	`ALTER TABLE state ADD COLUMN is_active bool`,
	`ALTER TABLE job DROP COLUMN created_at`,
	// migration can be not just SQL strings, but also callback functions. This is very usefull for datamigations
	// or other complex migrations where you can use golang code for some generation or processing.
	vsmt.MigrationFunc(func(tx *sql.Tx) error {
		for _, state := range []string{"Started", "In Proccess", "Finished"} {
			if _, err := tx.Exec("INSERT INTO state(name) VALUES($1)", state); err != nil {
				return err
			}
		}
		return nil
	}),
}

func main() {
	// create database connection
	db, err := sql.Open("postgres", "postgres://vsmt:vsmt@localhost/vsmt")
	if err != nil {
		fmt.Println("open database:", err)
		return
	}

	// migrations function expect open transaction and will exequte all queries inside this transaction
	tx, err := db.Begin()
	if err != nil {
		fmt.Println("create migration tx:", err)
		return
	}

	// defer commit migration transaction
	defer func() {
		if err := tx.Commit(); err != nil {
			fmt.Println("commit transaction:", err)
			return
		}
		fmt.Println("database migrated")
	}()

	// run migration process, if this first time call schema queries will be exequted else required queries from
	// migrations argument
	if err := vsmt.Migrate(tx, schema, migrations); err != nil {
		fmt.Println("do migrations:", err)
	}

}

Tests

For testing you should use real database connection.

1. Create database
2. Copy .env_example to .evn
3. Edit .env and replace VSMT_* variables with your values
4. Run testing go test .