migratus

Why Another migration tool?

There are some flaws in the existing migration libraries:

• Some of them depend on specific ORM's.
• Some of them store the state on the filesystem
• Some of them clash in specific scenarios

What are migratus features?

• It's Very small
• It's abstract. Does not make assumptions about your enviroment and database. (And therefore allows you to store your state in your database)
• It has a very simple programatic API

How does it work?

You can take a look at the example file provided. But basically:

Installation

npm install migratus

API

var migratus = require('migratus')(options);

Where options is:

{
  loader:loaderFunction,
  saver:saverFunction,
  directory:'/path/to/directory'
}

saver (function) will be called in form of (state, callback). It will store the state object and call the callback in form of (err) when saving is done.

loader (function) gets a callback and calls the callback in form of (err, state). state being the latest state of the database, previously saved by a saver function.

directory (string) is the directory that migrations are stored in

Events

Returned object is always an EventEmitter. It will fire two events:

migrate failed when a migration failes. It will provide arguments (name, direction, err)

migrate succeeded when a migration completes. It will provide arguments (name, direction)

Migrate to the latest migration

migratus.up(callback)

callback is a callback function which will be called when migration is done in form of (err)

Migrate to a specific migration

migratus.to(name, callback)

name is the name of the specific migration callback will be called when migration is done in form of (err)

Migrations

Each migration is a simple node module with two exported functions, up and down.

Example

var pg = require('pg');
var con = 'postgres://username:password@localhost/database';

module.exports.up = function(cb) {
  pg.connect(con, function(err, client, done) {
    client.query('ALTER TABLE foo ADD COLUMN bar', function(err) {
      done();
      cb(err);
    });
  });
}

module.exports.down = function(cb) {
  pg.connect(con, function(err, client, done) {
    client.query('ALTER TABLE foo DROP COLUMN bar', function(err) {
      done();
      cb(err);
    });
  });
}

Creating migrations

A very small cli tool is provided to help you create new migration files

node_modules/migratus/bin/create [--template /path/to/template] migration name

It will create a new migration file using provided template (optional) with migration name.

If you have defined $EDITOR, it will be opened automatically to the created migration file