Migrations

MikroORM has integrated support for migrations via umzug. It allows you to generate migrations with current schema difference.

By default, each migration will be all executed inside a transaction, and all of them will be wrapped in one master transaction, so if one of them fails, everything will be rolled back.

Migration class

Migrations are classes that extend Migration abstract class:

export class Migration20191019195930 extends Migration {
async up(): Promise<void> {
this.addSql('select 1 + 1');
}
}

To support undoing those changed, you can implement down method, which by default throws an error.

Transactions are by default wrapped in a transactions. You can override this behaviour on per transaction basis by implementing isTransactional(): boolean method.

Configuration object and driver instance are available in the Migration class context.

Configuration

await MikroORM.init({
// default values:
migrations: {
tableName: 'mikro_orm_migrations', // name of database table with log of executed transactions
path: './migrations', // path to the folder with migrations
transactional: true, // wrap each migration in a transaction
disableForeignKeys: true, // wrap statements with `set foreign_key_checks = 0` or equivalent
allOrNothing: true, // wrap all migrations in master transaction
},
})

Using via CLI

You can use it via CLI:

npx mikro-orm migration:create # Create new migration with current schema diff
npx mikro-orm migration:up # Migrate up to the latest version
npx mikro-orm migration:down # Migrate one step down
npx mikro-orm migration:list # List all executed migrations
npx mikro-orm migration:pending # List all pending migrations

For migration:up and migration:down commands you can specify --from (-f), --to (-t) and --only (-o) options to run only a subset of migrations:

npx mikro-orm migration:up --from 2019101911 --to 2019102117 # the same as above
npx mikro-orm migration:up --only 2019101923 # apply a single migration
npx mikro-orm migration:down --to 0 # migratee down all migrations

To run TS migration files, you will need to enable useTsNode flag in your package.json.

Using the Migrator programmatically

Or you can create simple script where you initialize MikroORM like this:

./migrate.ts

import { MikroORM } from 'mikro-orm';
(async () => {
const orm = await MikroORM.init({
dbName: 'your-db-name',
// ...
});
const migrator = orm.getMigrator();
await migrator.createMigration(); // creates file Migration20191019195930.ts
await migrator.up(); // runs migrations up to the latest
await migrator.up('up-to-name'); // runs migrations up to given version
await migrator.down('down-to-name'); // runs migrations down to given version
await migrator.down(); // migrates one step down
await migrator.down({ to: 0 }); // migrates down to the first version
await orm.close(true);
})();

Then run this script via ts-node (or compile it to plain JS and use node):

$ ts-node migrate

Limitations

MySQL

There is no way to rollback DDL changes in MySQL, implicit commit is forced for those queries automatically, so transactions are not working as expected.

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