`

run east -h to see detailed command help.

All options described above can be set via command line or at .eastrc file
located at current directory, e.g.:

`js

{
"dir": "./dbmigration",
"template": "./lib/node/utils/customMigrationTemplate.js"
}

`

.eastrc also can be a regular commonjs module (instead of json file):

`js

var path = require('path');

module.exports = {
dir: path.join(__dirname, 'dbmigration'),
template: './lib/node/utils/customMigrationTemplate.js'
};

`

east also supports config as ECMAScript module, config could be:

`js
import path from 'path';

export const dir = path.resolve('dbmigration');
export const template = path.resolve('./lib/node/utils/customMigrationTemplate.js');
``

See ECMAScript Modules support for details.

$3

`sh
east create doSomething
`

produces something like this

`sh
New migration "1_doSomething" created at "migrations/1_doSomething.js"
`

the created file will contain

`js
exports.tags = [];

exports.migrate = async (client) => {

};

exports.rollback = async (client) => {

};
`

* client represents a connection to the current db and it's determined by the
adapter (see adapters section)
* done callback may be defined as second argument - should be called at the
end of the migration (if any error occures you can pass it as the first argument)
* rollback function is optional and may be omitted

Migration file is a regular node.js module and allows migrating any database e.g.

`js
// include your database wrapper which you already use in app
const db = require('./db');

exports.migrate = async (client) => {
await db.connect();
await db.things.insert({_id: 1, name: 'apple', color: 'red'});
};

exports.rollback = async (client) => {
await db.connect();
await db.things.remove({_id: 1});
};
`

or you can use a special adapter for database (see adapters section).


#### Migration file number format

The default format for migration file names is to prepend a number to the
filename which is incremented with every new file. This creates migration files
such as "migrations/1_doSomething.js", "migrations/2_doSomethingElse.js".

If you prefer your files to be created with a date-time instead of sequential
numbers, you can set the migrationNumberFormat configuration parameter in
your .eastrc to "dateTime":

`json
{
"migrationNumberFormat": "dateTime"
}
`

This will create migration files with date-time prefix in YYYYMMDDhhmmss
format (e.g. "migrations/20190720172730_doSomething.js").

For the default behavior, you can omit the migrationNumberFormat
configuration option or set it to:

`json
{
"migrationNumberFormat": "sequentialNumber"
}
`

$3

let's create one more migration

`sh
east create doSomethingElse
`

then executes both of them

`sh
east migrate
`

it sequentially executes all new migrations and produces

`sh
target migrations:
1_doSomething
2_doSomethingElse
migrate "1_doSomething"
migration done
migrate "2_doSomethingElse"
migration done
`

selected migrations can be executed by passing their names (or numbers or
basenames or paths) as an argument

`sh
east migrate 1_doSomething 2
`

in our case this command will skip all of them

`sh
skip "1_doSomething" because it's already executed
skip "2_doSomethingElse" because it's already executed
nothing to migrate
`

you can pass --force option to execute already executed migrations.
This is useful while you develop and test your migration.

You also can export tags array from migration and then run only
migrations that satisfy the expression specified by --tag option. The expression
consists of tag names and boolean operators &, | and !. For example,
the following command will run all migrations that have "tag1" tag and do not have "tag2" tag:

`sh
east migrate --tag 'tag1 & !tag2'
`

$3

rollback has similar to migrate command syntax but executes rollback
function from the migration file

`sh
east rollback
`

will produce

`sh
target migrations:
2_doSomethingElse
1_doSomething
rollback "2_doSomethingElse"
migration successfully rolled back
rollback "1_doSomething"
migration successfully rolled back
`

$3

`sh
east list
`

shows new migrations e.g.

`sh
new migrations:
1_doSomething
2_doSomethingElse
`

target status could be specified as an argument e.g.

`sh
east list executed
`

Library usage

east exposes MigrationManager class (descendant of EventEmitter) which for
example can be used to migrate your database from node.js app without using
east cli:

`js
const {MigrationManager} = require('east');

const main = async () => {
const migrationManager = new MigrationManager();

// log target migrations before execution
migrationManager.once('beforeMigrateMany', (migrationNames) => {
console.log('Target migrations: ', migrationNames);
});

await migrationManager.configure();

try {
await migrationManager.connect();
// select for migration all not executed migrations
await migrationManager.migrate({status: 'new'});
}
finally {
await migrationManager.disconnect();
}
}

main().catch((err) => {
console.error('Some error occurred: ', err.stack || err);
});
``

MigrationManager methods:

* configure(params) - configures migration process, accepts object with
parameters (dir, adapter, etc) and merges it with loaded config (when
loadConfig param is truthy - true by default). Returns Promise. **This
method should be called before any other methods.**

getParams() - returns Promise* with parameters used by migration
process after configuration(configure method).

* init() - initiates migration process for a project. Should be called once
per project. Returns Promise.

* isInitialized() - checks whether init was made or not.
Returns Promise.

create(basename) - creates migration, returns Promise* with migration
object.

* getMigrationPath(name, migrationFileType) - returns an absolute path of the migration
file on disk by the name of the migration, migrationFileType can be one of
"executable" or "source" ("executable" by default). Returns Promise.

* connect() - connects to database management system (if supposed by
adapter). Returns Promise.

* getMigrationNames({migrations, status, tag, reverseOrderResult}) -
returns migrations names, following options are provided:

* migrations - array of target migrations, each migration could be
defined by basename, full name, path or number.
* status - status to filter migrations, supported statuses are:
"new", "executed" and "all".
* tag - tag expression to filter migrations e.g. "tag1 & !tag2"
* reverseOrderResult - if true then result array will be reversed.

migrations and status are mutually exclusive.
If migrations, status not provided then all migrations will be processed
(e.g. filtered by tag and returned).

* migrate({migrations, status, tag, force}) - executes target migrations.
Target migration could be defined by migrations, status, tag options
(see it's description at getMigrationNames method). By default
migrations with status "new" are chosen. Returns Promise. force
flag allows to execute already executed migrations.

* rollback({migrations, status, tag, force}) - rollbacks target migrations.
Target migration could be defined by migrations, status, tag options
(see it's description at getMigrationNames method). By default
migrations with status "executed" are chosen. Returns Promise. force
flag allows to rollback not executed migrations.

* disconnect() - disconnects from database management system (if supposed
by adapter). Returns Promise.


MigrationManager events:

* beforeMigrateOne({migration})
* afterMigrateOne({migration})
* beforeMigrateMany({migrationNames})
* afterMigrateMany({migrationNames})
* beforeRollbackOne({migration})
* afterRollbackOne({migration})
* beforeRollbackMany({migrationNames})
* afterRollbackMany({migrationNames})
* onSkipMigration({migration, reason})

Adapters

adapter determines where executed migration names will be stored and what will be
passed to migrate and rollback function as client.
Default adapter stores executed migration names at file .migrations which is
located at migrations executables directory and passes null as client.

Other adapters:
* mongodb
* sqlite
* postgres
* mysql
* couchbase
* couchdb
* dynamodb

Plugins

East functionality could be extended by using plugins, for usage instructions
see plugin page:

* migration duration logger
* migration progress indicator helper

Creating own adapter

For writing your own adapter you should implement methods for connection,
mark transaction as executed, etc see details inside
built-in adapter and other adapters.
See TypeScript support for the details on the required
adapter interface.

You also can run migrator tests from current repository against your adapter:

* Clone current repository
* Change current directory to it
* Create file .eastrc with path and parameters for
your adapter e.g.

`js
{
"adapter": "../../east-mysql/lib/adapter",
"url": "mysql://user:password@localhost/east_test_db",
"createDbOnConnect": true
}
`

* Run NODE_EAST_TEST_LOAD_CONFIG=1 npm run testSpecified test/01-migrator -- --jobs=1 at
root of the cloned repository.

TypeScript and other transpiled languages support

east allows you to opt-in writing and executing your migrations with any transpiled languages,
while by default it uses a single dir called "migrations" and looks for ".js" files in it.

You can configure separate executable and source files directories as well as
separate executable and source files extensions with --dir, --source-dir,
--migration-extension, --source-migration-extension respectively.

By default if you specify only --dir and/or --migration-extension, then
--source-dir and/or --source-migration-extension will be equal to it, however
it doesn't work on the other way around, e.g. if you specify

`
--source-dir mySourceDir --source-migration-extension ts
`

then --dir and --migration-extension will have migrations and js values by default,
so it is recommended to specify at least --dir, --source-dir and --source-migration-extension
when you are building a transpiled language.

If you use TypeScript you can run east with ts-node
if you don't want to transpile you migration scripts before running them:

`sh
ts-node $(which east) migrate
`

Just be sure to specify --migration-extension ts so that east does look for
TypeScript files when require()-ing the migration scripts.

$3

east exposes TypeScript declarations of the Adapter, MigrationManager
and other related interfaces.

You can access it by importing the interfaces from east module itself:

`ts
import { DbClient } from 'some-mainstream-db';
import type { Adapter, AdapterConstructor } from 'east';

class MyAdapter implements Adapter {
// go to definition of Adapter interface for documentation on required methods
// you can also leverage your ide features to generate
// stub method impementations here
}

// type-check the class static type (i.e. its constructor)
const _: AdpaterConstructor = MyAdapter;

export = MyAdapter;
`

ECMAScript Modules support

east provides support for es modules by --es-modules cli flag.
With this flag config, migrations, adapter and plugins will be loaded using
import expression.
It allows to provide those entities like commonjs or es modules, e.g.
.eastrc.mjs:

`js
import path from 'path';
export const dir = path.resolve('dbmigration');
export const template = path.resolve('./lib/node/utils/customMigrationTemplate.js');
``

Please note, that you need to enable nodejs es modules support (use mjs
extension for module or package.json with type "module", etc - see
nodejs esm docs for
details).

Config presented above could be used like this:

`sh
east --config .eastrc.mjs --es-modules list
`

When migration files as es module are desired --migration-extension and
--source-migration-extension` set to "mjs" could be used.

License

MIT