Migrating to step-by-step migrations with existing project

[sqcsabbey]

I'm trying to migrate an existing project to use step-by-step migrations, and my first of these would be migrating from schema versions 22 to 23. When I run drift_dev schema steps ..., I get the following generated in schema_versions.dart:

import 'package:drift/internal/versioned_schema.dart' as i0;
import 'package:drift/drift.dart' as i1;
import 'package:drift/drift.dart'; // ignore_for_file: type=lint,unused_import

// GENERATED BY drift_dev, DO NOT MODIFY.
i0.MigrationStepWithVersion migrationSteps() {
  return (currentVersion, database) async {
    switch (currentVersion) {
      default:
        throw ArgumentError.value('Unknown migration from $currentVersion');
    }
  };
}

i1.OnUpgrade stepByStep() =>
    i0.VersionedSchema.stepByStepHelper(step: migrationSteps());

With this, when I try to call migrationSteps, the from22To23 parameter isn't defined; this is how I tried to use it:

        await m.runMigrationSteps(
          from: max(22, from),
          to: to,
          steps: migrationSteps(
            from22To23: (m, schema) async {
              await m.addColumn(schema.features, schema.features.internal);
            },
          ),
        );

I've looked through the documentation, but I'm not sure what I'm missing. Could you please enlighten me?

[sqcsabbey]

My issue was that I tried to run dart run drift_dev schema steps ... against the dart versions of the frozen schemas, not the json ones. Do I have to still write the migration code (the await m.addColumn(schema.features, schema.features.internal); above), or is that handled now that the schema_versions.dart file generated successfully? The documentation makes it look like this addColumn would be generated, but I don't see it in my schema_versions.dart.

[sqcsabbey]

Found where I need to implement from22To23, I think I'm all set with this (still need to try it)?

I'm going to leave this here as someone else might run into a similar issue.

[simolus3]

The documentation makes it look like this addColumn would be generated, but I don't see it in my schema_versions.dart.

The docs mentions that the migrationSteps method will be generated and then shows how it would be used. So to clarify, you're still required to write your migrations manually. I tried figuring out migrations automatically by looking at diffs, but I think those approaches would always be unreliable since there is often more than one way to write migrations.