Are there any concepts for firestore db schema migrations comparable to rails ActiveRecord migrations?

Question

Our firestore DB based model evolves naturally. Now we would like to update all existing documents to the new (implicit) schema.

Are there any tools supporting that or what are the best practices. I would love to have a concept comparable to the rails ActiveRecord migrations.

Answer 1

I couldn't find a firestore schema migration tool, so I wrote fireway. It's currently very simple (it doesn't support reversing a migration), but it's been enough for my use case.

Here's an example migration script:

// migrations/v0.0.1__example.js

module.exports.migrate = async ({firestore}) => {
    await firestore.collection('name').add({key: 'value'});
};

Then run fireway migrate to migrate your default project.

Answer 2

Currently, for Firestore, you will have to write your own code to update all existing documents to the new (implicit) schema. I read a few weeks ago in a post, that Firestore team is working on making this easier in the future.

If your new schema require some changes in your entire database, you can also consider using Firestore import / export system, that allows you to dump your data into a GCS bucket. It is not in a JSON format as you probably expected but it is in a similar format as Cloud Datastore uses, so I think will help you solve this problem.