Provide a way to undo a migration if the migration file can't be found

[sheerun]

Provide a way to undo a migration if the migration file can't be found

[sheerun]

Sounds fine and convenient. I'd be up to review and merge if someone submitted such PR.

Implementation probably requires implementing customResolver for umzug that resolves database entries with fallback to local files. As well as changing implementation of storage so it returns list of migrations from both database and local filesystem.

Other things to note:

1. It needs to be backward-compatible, so engine should ensure before migration that column storing migration code is present or create and populate it in transaction otherwise (ensureTable method in engine).
2. Obviously it should also properly handle case when no migration table is present
3. It should support dry run
4. It should support --to argument
5. ???

[sheerun]

Also the behavior of the command you're imagining is different than both up (that is able to run only up migrations) and down (that executes only down migrations). It would need to figure out what is the common denominator for code migrations and database migrations, migrate down there, and then migrate upward with all remaining code migrations.

This command would be as dangerous as knex-migrate down, so we probably need a --force flag if running in production environment (NODE_ENV=production). knex-migrate up should be enough for production and is usually harmless, so no --force is necessary there.

I guess we could name it knex-migrate sync or something.

[carlbennettnz]

Sorry I forgot to get back to you on this. After some more thought, I don't think this would be a very good idea.

One major issue I didn't consider when I opened this issue is dependencies. Consider making a new branch, npm i moment, then making and applying a new migration that uses moment. Switching back to master, npm i to remove moment, then knex-migrate down wouldn't work, even with the solution is proposed above.

I'm also using external .sql files in my migrations in a few places. These wouldn't be present either.

For those reasons, I'm going to close this for now. Feel free to reopen if you can think of a better solution to the problem.