The umzug lib is a framework agnostic migration tool for Node.JS. The tool itself is not specifically related to databases but basically provides a clean API for running and rolling back tasks.
In order to keep track of already executed tasks, umzug logs successfully executed migrations. This is done in order to allow rollbacks of tasks. There are multiple storage presets available, from which you can choose. Adding a custom is super simple as well.
Using the json storage will create a JSON file which will contain an array with all the executed migrations. You can specify the path to the file. The default for that is umzug.json in the working directory of the process.
{
// The path to the json storage.
// Defaults to process.cwd() + '/umzug.json';
path: process.cwd() + '/db/sequelize-meta.json'
}Using the sequelize storage will create a table in your database called SequelizeMeta containing an entry for each executed migration. You will have to pass a configured instance of Sequelize or an existing Sequelize model. Optionally you can specify the model name, table name, or column name.
{
// The configured instance of Sequelize.
// Optional if `model` is passed.
sequelize: instance,
// The to be used Sequelize model.
// Must have column name matching `columnName` option
// Optional of `sequelize` is passed.
model: model,
// The name of the to be used model.
// Defaults to 'SequelizeMeta'
modelName: 'Schema',
// The name of table to create if `model` option is not supplied
// Defaults to `modelName`
tableName: 'Schema',
// The name of table column holding migration name.
// Defaults to 'name'.
columnName: 'migration',
// The type of the column holding migration name.
// Defaults to `Sequelize.STRING`
columnType: new Sequelize.STRING(100)
}In order to use a custom storage, you can create and publish a module which has to fulfill the following API. You can just pass the name of the module to the configuration and umzug will require it accordingly. The API that needs to be exposed looks like this:
var Bluebird = require('bluebird');
var redefine = require('redefine');
module.exports = redefine.Class({
constructor: function (options) {
this.options = options;
this.options.storageOptions = _.extend({
option1: 'defaultValue1'
}, this.options.storageOptions)
},
logMigration: function (migrationName) {
return new Bluebird(function (resolve, reject) {
// This function logs a migration as executed.
// It will get called once a migration was
// executed successfully.
});
},
unlogMigration: function (migrationName) {
return new Bluebird(function (resolve, reject) {
// This function removes a previously logged migration.
// It will get called once a migration has been reverted.
});
},
executed: function () {
return new Bluebird(function (resolve, reject) {
// This function lists the names of the logged
// migrations. It will be used to calculate
// pending migrations. The result has to be an
// array with the names of the migration files.
});
}
});Migrations are basically files that describe ways of executing and reverting tasks. In order to allow asynchronicity, tasks have return a Promise object which provides a then method.
A migration file ideally contains an up and a down method, which represent a function which achieves the task and a function that reverts a task. The file could look like this:
'use strict';
var Bluebird = require('bluebird');
module.exports = {
up: function () {
return new Bluebird(function (resolve, reject) {
// Describe how to achieve the task.
// Call resolve/reject at some point.
});
},
down: function () {
return new Bluebird(function (resolve, reject) {
// Describe how to revert the task.
// Call resolve/reject at some point.
});
}
};The umzug lib is available on npm:
npm install umzugThe basic usage of umzug is as simple as that:
var Umzug = require('umzug');
var umzug = new Umzug({});
umzug.someMethod().then(function (result) {
// do something with the result
});The execute method is a general purpose function that runs for every specified migrations the respective function.
umzug.execute({
migrations: ['some-id', 'some-other-id'],
method: 'up'
}).then(function (migrations) {
// "migrations" will be an Array of all executed/reverted migrations.
});You can get a list of pending/not yet executed migrations like this:
umzug.pending().then(function (migrations) {
// "migrations" will be an Array with the names of
// pending migrations.
});You can get a list of already executed migrations like this:
umzug.executed().then(function (migrations) {
// "migrations" will be an Array of already executed migrations.
});The up method can be used to execute all pending migrations.
umzug.up().then(function (migrations) {
// "migrations" will be an Array with the names of the
// executed migrations.
});It is also possible to pass the name of a migration in order to just run the migrations from the current state to the passed migration name.
umzug.up({ to: '20141101203500-task' }).then(function (migrations) {});Running specific migrations while ignoring the right order, can be done like this:
umzug.up({ migrations: ['20141101203500-task', '20141101203501-task-2'] });There are also shorthand version of that:
umzug.up('20141101203500-task'); // Runs just the passed migration
umzug.up(['20141101203500-task', '20141101203501-task-2']);Running
The down method can be used to revert the last executed migration.
umzug.down().then(function (migration) {
// "migration" will the name of the reverted migration.
});It is possible to pass the name of a migration until which the migrations should be reverted. This allows the reverse of multiple migrations at once.
umzug.down({ to: '20141031080000-task' }).then(function (migrations) {
// "migrations" will be an Array with the names of all reverted migrations.
});Reverting specific migrations while ignoring the right order, can be done like this:
umzug.down({ migrations: ['20141101203500-task', '20141101203501-task-2'] });There are also shorthand version of that:
umzug.down('20141101203500-task'); // Runs just the passed migration
umzug.down(['20141101203500-task', '20141101203501-task-2']);It is possible to configure umzug instance via passing an object to the constructor. The possible options are:
{
// The storage.
// Possible values: 'json', 'sequelize', an object
storage: 'json',
// The options for the storage.
// Check the available storages for further details.
storageOptions: {},
// The logging function.
// A function that gets executed everytime migrations start and have ended.
logging: false,
// The name of the positive method in migrations.
upName: 'up',
// The name of the negative method in migrations.
downName: 'down',
migrations: {
// The params that gets passed to the migrations.
// Might be an array or a synchronous function which returns an array.
params: [],
// The path to the migrations directory.
path: 'migrations',
// The pattern that determines whether or not a file is a migration.
pattern: /^\d+[\w-]+\.js$/,
// A function that receives and returns the to be executed function.
// This can be used to modify the function.
wrap: function (fun) { return fun; }
}
}MIT