save/load feature for colyseus schema objects

README.md

I'm adding a save/load feature to my WIP game and thought someone might find this small module useful

example usage:

const saveGameData = new SaveGame(); // make a custom schema for saved games data
... /* add all state objects from your game manager to saveGameData */
const serialized = await schemaToString(saveGameData);
... /* save to file, read from file etc. */
const loadedGameData: SaveGame = await stringToSchema(SaveGame, serialized );
... /* take game state object from loadedGameData into your game manager */

https://raw.githubusercontent.com/starwards/starwards/1a35eea8aacb80ef704df9bbd246a115f653b042/modules/server/src/serialization/game-state-serialization.ts

schema-serialization.ts

import { gzip, unzip } from 'node:zlib';

import { Schema } from '@colyseus/schema';
import { promisify } from 'node:util';

const do_gzip = promisify(gzip);
const do_unzip = promisify(unzip);

export async function schemaToString(fragment: Schema) {
    const zipped = await do_gzip(Buffer.from(fragment.encodeAll()));
    return zipped.toString('base64');
}
type Constructor<T extends Schema> = new (...args: unknown[]) => T;

export async function stringToSchema<T extends Schema>(ctor: Constructor<T>, serialized: string) {
    const unzipped = await do_unzip(Buffer.from(serialized, 'base64'));
    const result = new ctor();
    result.decode([...unzipped]);
    return result;
}