How to run SQLite custom migration inside brick migration flow?

[stefanorumi7]

Problem

I need to run a SQLite migration to migrate some data from one entity to another, and it needs to be executed in a certain order corresponding the rest of the brick migrations.

Example

• I have the following relationships: EntityA -> EntityB -> EntityC already working in PRD.
• I need to change it to the following: EntityA -> EntityC
• So I need to run a migration with an UPDATE statement for all EntityA to copy the reference to EntityC from EntityB.

Question

Is there a way to run custom SQL following the migration order that brick is following so far?

[tshedor]

@stefanorumi7 depending on how custom you're trying to go, you can either implement a MigrationCommand instance or you can manually create a migration using one the existing commands. In both cases, you'd want to use a version number that places it in the right sequence

[stefanorumi7]

That didn't work for me, but after some iterations the AI got a solution for me.

It crafted a migration with this format:

// GENERATED CODE EDIT WITH CAUTION
// THIS FILE **WILL NOT** BE REGENERATED
// This file should be version controlled and can be manually edited.
part of 'schema.g.dart';

// The migration version must **always** mirror the file name

// Custom command to execute raw SQL for data migration
// Using private class to avoid build_runner trying to serialize it
class _UpdateColumnBCommand extends MigrationCommand {
  const _UpdateColumnBCommand();

  @override
  String get statement =>
      '''UPDATE EntityA SET columnB = CASE WHEN columnA = 1 THEN 'value1' ELSE 'otherValue' END WHERE columnB IS NULL''';

  @override
  String get forGenerator => '_UpdateColumnBCommand()';
}

const List<MigrationCommand> _migration_20251020140928_up = [
  _UpdateColumnBCommand(),
];

const List<MigrationCommand> _migration_20251020140928_down = [
  // No down migration needed - we keep the data as is
];

//
// DO NOT EDIT BELOW THIS LINE
//

@Migratable(
  version: '20251020140928',
  up: _migration_20251020140928_up,
  down: _migration_20251020140928_down,
)
class Migration20251020140928 extends Migration {
  const Migration20251020140928()
    : super(
        version: 20251020140928,
        up: _migration_20251020140928_up,
        down: _migration_20251020140928_down,
      );
}

And I plugged it in the schema.dart as any other migration.

[stefanorumi7]

The next migration generation after having the custom one that I added was failing due to a check on the brick side. I created this PR to fix it: #651