README.md

Versioned migrations for MongoDB

This package allows to perform versioned migrations on your MongoDB using mgo driver. It depends only on standard library and mgo driver. Inspired by go-pg migrations.

Table of Contents

• Prerequisites
• Installation
• Usage
  • Use case #1. Migrations in files.
  • Use case #2. Migrations in application code.
• How it works?
• License

Prerequisites

• Golang >= 1.10 or Vgo

Installation

go get -v -u github.com/xakep666/mongo-migrate

Usage

Use case #1. Migrations in files.

• Create a package with migration files. File name should be like <version>_<description>.go.

1_add-my-index.go

package migrations

import (
	"github.com/globalsign/mgo"
	"github.com/globalsign/mgo/bson"
	migrate "github.com/xakep666/mongo-migrate"
)

func init() {
	migrate.Register(func(db *mgo.Database) error {
		return db.C("my-coll").Insert(EnsureIndex(mgo.Index{Name: "my-index", Key: []string{"my-key"}}))
	}, func(db *mgo.Database) error {
		return db.C("my-coll").DropIndexName("my-index")
	})
}

• Import it in your application.

import (
    ...
    migrate "github.com/xakep666/mongo-migrate"
    _ "path/to/migrations_package" // database migrations
    ...
)

• Run migrations.

func MongoConnect(host, user, password, database string) (*mgo.Database, error) {
    session, err := mgo.DialWithInfo(&mgo.DialInfo{
        Addrs: []string{host},
        Database: database,
        Username: user,
        Password: password,
    })
    if err != nil {
        return nil, err
    }
    db := session.DB("")
    migrate.SetDatabase(db)
    if err := migrate.Up(migrate.AllAvailable); err != nil {
        return nil, err
    }
    return db, nil
}

Use case #2. Migrations in application code.

• Just define it anywhere you want and run it.

func MongoConnect(host, user, password, database string) (*mgo.Database, error) {
    session, err := mgo.DialWithInfo(&mgo.DialInfo{
        Addrs: []string{host},
        Database: database,
        Username: user,
        Password: password,
    })
    if err != nil {
        return nil, err
    }
    db := session.DB("")
    m := migrate.NewMigrate(db, migrate.Migration{
        Version: 1,
        Description: "add my-index",
        Up: func(db *mgo.Database) error {
            return db.C("my-coll").EnsureIndex(mgo.Index{Name: "my-index", Key: []string{"my-key"}})
        },
        Down: func(db *mgo.Database) error {
            return db.C("my-coll").DropIndexName("my-index")
        },
    })
    if err := m.Up(migrate.AllAvailable); err != nil {
        return nil, err
    }
    return db, nil
}

How it works?

This package creates a special collection (by default it`s name is "migrations") for versioning. In this collection stored documents like

{
    "_id": "<mongodb-generated id>",
    "version": 1,
    "description": "add my-index",
    "timestamp": "<when applied>"
}

Current database version determined as version from latest inserted document.

You can change collection name using SetMigrationsCollection methods. Remember that if you want to use custom collection name you need to set it before running migrations.

License

mongo-migrate project is licensed under the terms of the MIT license. Please see LICENSE in this repository for more details.