/** * A {@link Migration} contains a target version and a migrate function. * * The version is used to determine whether the migration has yet to be applied * or if it needs to be skipped, see {@link SkipMigrationFn} for details. * * The migrate function should take the data you pass through {@link migrate} * and modify it to your needs. */ export type Migration = { version: V; migrate: (data: any) => Promise; }; /** * A function that determines if a {@link Migration} should be skipped. * * The first argument will be the version of the current {@link Migration} being * tested, while the second argument will be the version passed into * {@link migrate}. * * If left undefined, `a < b` will be used. This works for {@link Date dates}, * {@link Number numbers} and {@link String strings}. So if you want to use a * different type for versioning you should create your own function. */ export type SkipMigrationFn = (a: V, b: V) => boolean; /** * Migrate some data to the specified version. * * See {@link Migration} and {@link SkipMigrationFn} for details on creating * migrations and a custom skip function. */ export async function migrate( data: unknown, version: V, migrations: Array>, skip: SkipMigrationFn = (a, b) => a < b, ): Promise { let migratedData = data; for (const migration of migrations) { if (skip(migration.version, version)) { continue; } migratedData = migration.migrate(migratedData); } return migratedData; }