validateApplied method

Future<List<StmtMigration>> validateApplied(List<StmtMigration> migrations, List<MigrationRecord> existing)

Implementation

Future<List<StmtMigration>> validateApplied(
  List<StmtMigration> migrations,
  List<MigrationRecord> existing,
) async {
  // `existing` migrations may contain migrations
  // received at runtime that are not bundled in the app
  // i.e. those are not present in `migrations`
  // Thus, `existing` may be longer than `migrations`.
  // So we should only compare a prefix of `existing`
  // that has the same length as `migrations`

  // take a slice of `existing` migrations
  // that will be checked against `migrations`
  final existingPrefix = existing.slice(0, migrations.length);

  // First we validate that the existing records are the first migrations.
  for (var i = 0; i < existingPrefix.length; i++) {
    final migrationRecord = existingPrefix[i];
    final version = migrationRecord.version;

    final migration = migrations[i];

    if (migration.version != version) {
      throw SatelliteException(
        SatelliteErrorCode.unknownSchemaVersion,
        kSchemaVersionErrorMsg,
      );
    }
  }

  // Then we can confidently slice and return the non-existing.
  return migrations.slice(existingPrefix.length);
}