func DBVersion()

in tools/migration/rdbms/migrationlib/version.go [28:83]

• 40 lines of code
• 11 McCabe index (conditional complexity)

func DBVersion(db queryExecutor) (uint64, error) {

	rows, err := db.Query(fmt.Sprintf("select version_id, is_applied from %s order by id desc", goose.TableName()))
	if err != nil {
		if mysqlErr, ok := err.(*mysql.MySQLError); ok {
			if mysqlErr.Number == 1146 {
				// db versioning table does not exist, assume version 0
				return 0, nil
			}
		}
		return 0, fmt.Errorf("could not retrieve db version, error %+v, %T: %w", err, err, err)
	}
	defer rows.Close()

	toSkip := make([]uint64, 0)

	for rows.Next() {
		var (
			versionID uint64
			isApplied bool
		)
		if err = rows.Scan(&versionID, &isApplied); err != nil {
			return 0, fmt.Errorf("could not scan row: %w", err)
		}

		// the is_applied field tracks whether the migration was an
		// up or down migration. If we see a down migration, while
		// going through the records in descending order, then we
		// should skip that version altogether.
		skip := false
		for _, v := range toSkip {
			if v == versionID {
				skip = true
				break
			}
		}

		if skip {
			continue
		}

		if isApplied {
			return versionID, nil
		}

		// latest version of migration has not been applied.
		toSkip = append(toSkip, versionID)
	}
	if err := rows.Err(); err != nil {
		return 0, fmt.Errorf("could not retrieve db version: %w", err)
	}

	// if we couldn't figure out the db version, assume we are working on version 0
	// i.e. the db is not versioned yet.
	return 0, nil
}