mmk import

Adopt an existing migrate-mongo changelog into mongo-migrate-kit. One-time and forward-only — the source collection is never modified.

mmk import [options]

Usage

mmk import                       # adopt the migrate-mongo `changelog` collection
mmk import --from changelog      # explicit source collection
mmk import --to _mmk_migrations  # explicit target collection
mmk import --dry-run             # preview the mapping, write nothing
mmk import --trust-hash          # reuse migrate-mongo's fileHash instead of recomputing

How it works

mmk import reads your migrate-mongo changelog and records that history in the mmk changelog, so a subsequent mmk up runs only what's new. Files on disk that aren't in the source changelog stay pending. Each imported migration gets a unique, sequential batch number continuing after any existing records.

◎ Imported 12 migrations from `changelog` → `_mmk_migrations`

Options

Option	Default	Description
--from <collection>	changelog	Source migrate-mongo collection (read-only, never modified).
--to <collection>	config migrationsCollection	Target mmk collection.
--dry-run	—	Preview the mapping and write nothing.
--trust-hash	—	Reuse migrate-mongo's fileHash instead of recomputing the checksum from disk.
--force	—	Import into a non-empty mmk changelog (batches continue after the current max).
--no-lock	—	Skip the concurrency lock. Dev only.
--json	—	Emit the import result as JSON.

Plus the global flags.

Checksum mapping

For each imported record, the checksum is resolved as:

1. Reuse migrate-mongo's fileHash when it matches the on-disk SHA-256 (or always, under --trust-hash).
2. Otherwise recompute it from the file on disk.
3. Otherwise store '' and warn (file missing).

Forward-only safety

Imported records are tagged origin: 'migrate-mongo'. Because their files use migrate-mongo's positional up(db, client) signature, mmk down and mmk redorefuse them up front with a clear reason — so the collection is never left half-reverted. New migrations you author with mmk create remain fully reversible.

Non-empty target

If the target collection already has records, mmk import throws ImportTargetNotEmptyError unless you pass --force. A forced re-import is stable — records being overwritten are excluded from the batch offset.

See the migration guide for the full switch-over walkthrough.