o1js/src/examples/zkapps/local-events-zkapp.ts

TypeScript framework for zk-SNARKs and zkApps

import {
  Field,
  state,
  State,
  method,
  PrivateKey,
  SmartContract,
  Mina,
  AccountUpdate,
  UInt32,
  PublicKey,
  Struct,
} from 'o1js';

const doProofs = false;

class Event extends Struct({ pub: PublicKey, value: Field }) {}

class LocalEvents extends SmartContract {
  @state(Field) x = State<Field>();

  events = {
    complexEvent: Event,
    simpleEvent: Field,
  };

  init() {
    super.init();
    this.x.set(initialState);
  }

  @method async update(y: Field) {
    this.emitEvent('complexEvent', {
      pub: PrivateKey.random().toPublicKey(),
      value: y,
    });
    this.emitEvent('simpleEvent', y);
    let x = this.x.get();
    this.x.requireEquals(x);
    this.x.set(x.add(y));
  }
}

let Local = await Mina.LocalBlockchain({ proofsEnabled: false });
Mina.setActiveInstance(Local);

// a test account that pays all the fees, and puts additional funds into the zkapp
const [feePayer] = Local.testAccounts;

let contractAccount = Mina.TestPublicKey.random();
let contract = new LocalEvents(contractAccount);

let initialState = Field(1);

if (doProofs) {
  console.log('compile');
  await LocalEvents.compile();
}

console.log('deploy');
let tx = await Mina.transaction(feePayer, async () => {
  AccountUpdate.fundNewAccount(feePayer);
  await contract.deploy();
});
await tx.sign([feePayer.key, contractAccount.key]).send();

console.log('call update');
tx = await Mina.transaction(feePayer, async () => {
  await contract.update(Field(1));
});
await tx.prove();
await tx.sign([feePayer.key]).send();

console.log('call update');
tx = await Mina.transaction(feePayer, async () => {
  await contract.update(Field(2));
});
await tx.prove();
await tx.sign([feePayer.key]).send();

console.log('---- emitted events: ----');
// fetches all events from zkapp starting block height 0
let events = await contract.fetchEvents(UInt32.from(0));
console.log(events);
console.log('---- emitted events: ----');
// fetches all events from zkapp starting block height 0 and ending at block height 10
events = await contract.fetchEvents(UInt32.from(0), UInt32.from(10));
console.log(events);
console.log('---- emitted events: ----');
// fetches all events
events = await contract.fetchEvents();
console.log(events);