medic / js-migrations

Migrate a JavaScript object between versions

JavaScript Migrations

Installation

npm install js-migrations or kanso

Defining Migrations

A migration is an object with a version and one or both of up and down functions, which migrate up to, or down from this version respectively. For example:

var myMigration = {
  version: '1.2.5',
  up: function(obj, callback) {
    var num = parseInt(obj.a);
    if (isNaN(num)) {
      return { error: 'a is not a number' };
    } else {
      obj.a = num
      return { error: false, result: obj };
    }
  },
  down: function(obj, callback) {
    obj.a = obj.a + '';
    return { error: false, result: obj };
  }
};

Version should be unique between migrations or there will be no way to tell which set of migrations have been run.

Running Migrations

var migration = require('js-migrations');
var migrated = migration.migrate(
  { a: '42' },
  [ myMigration ],
  { from: '1.1.5', to: '2.1.3' }
);
if (migrated.err) throw migrated.err;
var obj = migrated.result;

If from or to is omitted above there will be no lower or upper limit respectively. If both are omitted all migrations will be run. If from is greater than to then the down migrations are run.

All versions must follow the semver format.

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