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Struct - Custom Data Structures

The Struct type allows you to create custom data structures by grouping related data fields together. It's useful for organizing complex data and creating reusable data models.

Import​

import { StructTemplate, StructFactory, Struct } from "@wakeuplabs/as-stylus";

Syntax​

@StructTemplate
class StructName {
  field1: Type1;
  field2: Type2;
  field3: Type3;
}

Overview​

Struct provides:

  • Custom data grouping
  • Related field organization
  • Reusable data models
  • Type-safe field access
  • Memory-efficient storage

Basic Usage​

Simple Struct​

import {
  Contract,
  StructTemplate,
  External,
  View,
  U256,
  Str,
  StructFactory,
} from "@wakeuplabs/as-stylus";

@StructTemplate
class UserInfo {
  id: U256;
  name: Str;
  isActive: boolean;
}

@Contract
export class UserManager {
  currentUser: Struct<UserInfo>;

  @External
  createUser(id: U256, name: Str): void {
    this.currentUser.id = id;
    this.currentUser.name = name;
    this.currentUser.isActive = true;
  }

  @View
  getUser(): UserInfo {
    return this.currentUser;
  }
}

Struct with Multiple Fields​

import {
  Contract,
  Struct,
  External,
  View,
  U256,
  Address,
  StructFactory,
} from "@wakeuplabs/as-stylus";

class TokenInfo {
  amount: U256;
  recipient: Address;
  timestamp: U256;
}

@Contract
export class TokenTracker {
  lastTransfer: Struct<TokenInfo>;

  @External
  recordTransfer(amount: U256, recipient: Address, timestamp: U256): void {
    this.lastTransfer.amount = amount;
    this.lastTransfer.recipient = recipient;
    this.lastTransfer.timestamp = timestamp;
  }

  @View
  getLastTransfer(): TokenInfo {
    return this.lastTransfer;
  }
}

Common Patterns​

Configuration Data​

import { Contract, Struct, External, U256, Address } from "@wakeuplabs/as-stylus";

class Config {
  maxSupply: U256;
  ownerAddress: Address;
  isPaused: boolean;
}

@Contract
export class ConfigContract {
  settings: TokenInfo<Config>;

  @External
  updateConfig(maxSupply: U256, owner: Address, paused: boolean): void {
    this.settings.maxSupply = maxSupply;
    this.settings.ownerAddress = owner;
    this.settings.isPaused = paused;
  }
}

Game Data​

import { Contract, External, Struct, View, U256, StructFactory } from "@wakeuplabs/as-stylus";

class PlayerStats {
  level: U256;
  score: U256;
  lives: U256;
}

@Contract
export class GameContract {
  player: Struct<PlayerStats>;

  @External
  updateStats(level: U256, score: U256, lives: U256): void {
    this.player.level = level;
    this.player.score = score;
    this.player.lives = lives;
  }

  @View
  getStats(): PlayerStats {
    return this.player;
  }
}

Supported Field Types​

import { U256, I256, Address, Str } from "@wakeuplabs/as-stylus";

class AllTypes {
  numberField: U256; // ✅ Numbers
  signedField: I256; // ✅ Signed numbers
  addressField: Address; // ✅ Addresses
  textField: Str; // ✅ Text
  flagField: boolean; // ✅ True/false
}

🏗️ More Data Structures

MappingKey-value storageMappingNestedNested key-value storageStructCustom data structures