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Type Alias: SaveMigrationFn()<T>

SaveMigrationFn<T> = (data) => T

Defined in: packages/core/src/saves/migrations/types.ts:47

A function that migrates game save data from one version to another.

Migration functions should be pure (no side effects) and should always return a new object rather than mutating the input.

Type Parameters​

T​

T extends MigrationGameSaveState = GameSaveState

The shape of the game save state for this migration. Can be a partial type if the migration only touches specific fields. Defaults to GameSaveState.

Parameters​

data​

T

The game save state at the source version

Returns​

T

The migrated game save state at the target version

Examples​

Basic migration without specific types:

const migrateFn: SaveMigrationFn = (data) => {
  return {
    ...data,
    player: {
      ...data.player,
      health: data.player.hp ?? 100, // Rename hp to health
    }
  };
};

Type-safe migration with specific field types:

const migrateFn: SaveMigrationFn<{ player?: { inventory: string[] } }> = (data) => {
  const player = data.player || {};
  return {
    ...data,
    player: {
      ...player,
      inventory: [], // TypeScript knows this should be string[]
    }
  };
};