abstrucked/hytopia-persisted-data

HYTOPIA Persisted Data

This skill helps you save and load persistent data in HYTOPIA SDK games.

Documentation: https://dev.hytopia.com/sdk-guides/persisted-data

When to Use This Skill

Use this skill when the user:

• Wants to save player progress between sessions
• Needs to create leaderboards or high scores
• Asks about storing game configuration
• Wants persistent inventories or unlocks
• Needs to save world state
• Asks about data persistence across server restarts

Data Types

| Type | Scope | Use Cases | |------|-------|-----------| | Global Data | All game instances | Leaderboards, game config, shared state | | Player Data | Per player | Progress, inventory, stats, preferences |

Global Data

Shared across all running game instances.

Set Global Data

import { PersistenceManager } from 'hytopia';

// Save global data
await PersistenceManager.instance.setGlobalData('leaderboard', [
  { name: 'Player1', score: 1000 },
  { name: 'Player2', score: 950 },
  { name: 'Player3', score: 900 }
]);

// Save game config
await PersistenceManager.instance.setGlobalData('game-config', {
  maxPlayers: 20,
  roundDuration: 300,
  difficulty: 'hard'
});

Get Global Data

import { PersistenceManager } from 'hytopia';

// Get leaderboard
const leaderboard = await PersistenceManager.instance.getGlobalData('leaderboard');
console.log('Top scores:', leaderboard);

// Get with default
const config = await PersistenceManager.instance.getGlobalData('game-config');
if (!config) {
  // Use defaults
}

Player Data

Persisted per player across sessions.

Set Player Data

import { Player } from 'hytopia';

// Save player progress
await player.setPersistedData('level', 15);
await player.setPersistedData('xp', 2500);
await player.setPersistedData('gold', 1000);

// Save complex data
await player.setPersistedData('inventory', [
  { id: 'sword', quantity: 1 },
  { id: 'potion', quantity: 5 },
  { id: 'key', quantity: 3 }
]);

await player.setPersistedData('unlocks', {
  skins: ['default', 'warrior', 'mage'],
  maps: ['forest', 'desert'],
  achievements: ['first-kill', 'speedrun']
});

Get Player Data

import { Player } from 'hytopia';

// Get player progress
const level = await player.getPersistedData('level') || 1;
const xp = await player.getPersistedData('xp') || 0;
const gold = await player.getPersistedData('gold') || 100;

// Get inventory
const inventory = await player.getPersistedData('inventory') || [];

// Load player on join
world.onPlayerJoin = async (player) => {
  const savedData = await player.getPersistedData('progress');

  if (savedData) {
    player.setData('level', savedData.level);
    player.setData('xp', savedData.xp);
    player.setHealth(savedData.health);
    console.log(`Loaded ${player.username}'s progress`);
  } else {
    // New player - set defaults
    player.setData('level', 1);
    player.setData('xp', 0);
    console.log(`New player: ${player.username}`);
  }
};

Shallow Merging

When updating object data, HYTOPIA performs shallow merging at the root level.

// Initial data
await player.setPersistedData('stats', {
  kills: 10,
  deaths: 5,
  playtime: 3600
});

// Update only kills - other fields preserved
await player.setPersistedData('stats', {
  kills: 15
});
// Result: { kills: 15, deaths: 5, playtime: 3600 }

// WARNING: Nested objects are replaced entirely
await player.setPersistedData('settings', {
  audio: { music: 0.5, sfx: 1.0 },
  video: { quality: 'high' }
});

await player.setPersistedData('settings', {
  audio: { music: 0.3 }  // sfx is LOST!
});
// Result: { audio: { music: 0.3 }, video: { quality: 'high' } }

Safe Nested Updates

// Always fetch, modify, and save for nested data
async function updateNestedSetting(player: Player, path: string, value: any) {
  const settings = await player.getPersistedData('settings') || {};

  // Deep update
  const keys = path.split('.');
  let obj = settings;
  for (let i = 0; i < keys.length - 1; i++) {
    obj[keys[i]] = obj[keys[i]] || {};
    obj = obj[keys[i]];
  }
  obj[keys[keys.length - 1]] = value;

  await player.setPersistedData('settings', settings);
}

// Usage
await updateNestedSetting(player, 'audio.music', 0.3);

Common Patterns

Leaderboard System

import { PersistenceManager } from 'hytopia';

async function updateLeaderboard(playerName: string, score: number) {
  // Get current leaderboard
  const leaderboard = await PersistenceManager.instance.getGlobalData('leaderboard') || [];

  // Check if player already on board
  const existingIndex = leaderboard.findIndex(e => e.name === playerName);

  if (existingIndex !== -1) {
    // Update if new score is higher
    if (score > leaderboard[existingIndex].score) {
      leaderboard[existingIndex].score = score;
    }
  } else {
    // Add new entry
    leaderboard.push({ name: playerName, score });
  }

  // Sort and keep top 100
  leaderboard.sort((a, b) => b.score - a.score);
  const top100 = leaderboard.slice(0, 100);

  await PersistenceManager.instance.setGlobalData('leaderboard', top100);
  return top100;
}

async function getLeaderboard(limit: number = 10) {
  const leaderboard = await PersistenceManager.instance.getGlobalData('leaderboard') || [];
  return leaderboard.slice(0, limit);
}

Auto-Save System

class AutoSave {
  private saveInterval: number = 60000;  // 1 minute
  private dirty: Set<string> = new Set();

  constructor() {
    setInterval(() => this.saveAll(), this.saveInterval);
  }

  markDirty(playerId: string) {
    this.dirty.add(playerId);
  }

  async saveAll() {
    for (const playerId of this.dirty) {
      const player = world.getPlayer(playerId);
      if (player) {
        await this.savePlayer(player);
      }
    }
    this.dirty.clear();
    console.log(`Auto-saved ${this.dirty.size} players`);
  }

  async savePlayer(player: Player) {
    await player.setPersistedData('progress', {
      level: player.getData('level'),
      xp: player.getData('xp'),
      gold: player.getData('gold'),
      inventory: player.getData('inventory'),
      lastSaved: Date.now()
    });
  }
}

const autoSave = new AutoSave();

// Mark player dirty when they change
function addXP(player: Player, amount: number) {
  const currentXP = player.getData('xp') || 0;
  player.setData('xp', currentXP + amount);
  autoSave.markDirty(player.id);
}

Save on Disconnect

world.onPlayerLeave = async (player) => {
  // Save all player data before they leave
  await player.setPersistedData('progress', {
    level: player.getData('level'),
    xp: player.getData('xp'),
    position: player.position,
    inventory: player.getData('inventory'),
    lastPlayed: Date.now()
  });

  console.log(`Saved ${player.username}'s progress`);
};

Unlockables System

async function unlockItem(player: Player, category: string, itemId: string) {
  const unlocks = await player.getPersistedData('unlocks') || {};

  if (!unlocks[category]) {
    unlocks[category] = [];
  }

  if (!unlocks[category].includes(itemId)) {
    unlocks[category].push(itemId);
    await player.setPersistedData('unlocks', unlocks);
    player.sendMessage(`Unlocked: ${itemId}!`);
    return true;
  }

  return false;  // Already unlocked
}

async function hasUnlock(player: Player, category: string, itemId: string) {
  const unlocks = await player.getPersistedData('unlocks') || {};
  return unlocks[category]?.includes(itemId) || false;
}

// Usage
await unlockItem(player, 'skins', 'golden-armor');
const hasSkin = await hasUnlock(player, 'skins', 'golden-armor');

Environment Configuration

Local Development

Data persists in auto-generated dev/ directory between restarts.

Tip: Use single browser tabs during local testing - player IDs are assigned sequentially starting at 1 after server restarts.

Production

Set environment variables:

• NODE_ENV=production
• HYTOPIA_API_KEY - Your API key
• HYTOPIA_GAME_ID - Your game ID
• HYTOPIA_LOBBY_ID - Your lobby ID

Upon deployment, HYTOPIA automatically configures persistence services.

Best Practices

1. Save on important actions - Don't wait for disconnect
2. Use auto-save - Backup every few minutes
3. Handle missing data - Always provide defaults
4. Validate loaded data - Check for corruption/outdated formats
5. Batch updates - Don't save on every tiny change
6. Version your data - Include version number for migrations
7. Test with fresh data - Delete dev/ folder to test new player flow

Data Migration Example

const CURRENT_VERSION = 2;

async function loadPlayerData(player: Player) {
  const data = await player.getPersistedData('progress');

  if (!data) {
    return getDefaultData();
  }

  // Migrate old data formats
  if (!data.version || data.version < CURRENT_VERSION) {
    const migrated = migrateData(data);
    await player.setPersistedData('progress', migrated);
    return migrated;
  }

  return data;
}

function migrateData(data: any) {
  let migrated = { ...data };

  // v1 -> v2: inventory format changed
  if (!data.version || data.version < 2) {
    if (Array.isArray(data.inventory)) {
      migrated.inventory = data.inventory.map(item =>
        typeof item === 'string'
          ? { id: item, quantity: 1 }
          : item
      );
    }
  }

  migrated.version = CURRENT_VERSION;
  return migrated;
}

Common Mistakes

• Not handling null/undefined when data doesn't exist
• Saving too frequently (causes performance issues)
• Not saving before player disconnects
• Forgetting shallow merge behavior for nested objects
• Not testing with fresh player data