Migrations for MongoDB

[gitcommitshow]

I see that the latest release server has migrations only for Postgres at the moment. I propose to create similar migrations for MongoDB users who want to upgrade from v1.3 to latest version. I would love to create a PR for the same. @ArekSredzki

How I plan to do that:

1. Review migrations for Postgres.
2. For MongoDB, I think only Update and Constraint related command will be relevant. So write mongodb equivalent for those lines only.
3. Figure out how to integrate these new changes in db-migrate in the context of mongodb.

Questions I have

1. As I see there some new collections/fields have been added, is there any requirement of writing bootstrap data as well?
2. Any other suggestions before I jump into this?

[zaourzag]

Hi, I was looking around if I could find mongodb. Seeing that i prefer it all day any day over postgress. 2. Prob just write it in docs that mongo is supported.

[gitcommitshow]

Yes. I think what's pending to call it mongodb supported is this issue only i.e. "writing mongodb migrations". This project uses waterline ORM so you should be able to work with all the databases that waterline supports. But as I see that the author uses postgres as their choice of db and tests the project for that only. The migrations are written for that only. So when we upgrade the project while using mongodb, we can't say for sure that the application won't break.

[gitcommitshow]

While fixing this, ran into blocker issue #297