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Asset Transfer Subscription

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Description

Section titled “Description”

This example demonstrates ASA lifecycle subscription.

  • Subscribe to asset creation with assetCreate filter
  • Subscribe to asset transfers with type and assetId filters
  • Track opt-in and transfer transactions

Prerequisites

Section titled “Prerequisites”
  • LocalNet running (via algokit localnet start)

Run This Example

Section titled “Run This Example”

From the repository’s examples/subscriber directory:

Terminal window
cd examples/subscriber
npx tsx 04-asset-transfer.ts

Code

Section titled “Code”

View source on GitHub

04-asset-transfer.ts
/**
 * Example: Asset Transfer Subscription
 *
 * This example demonstrates ASA lifecycle subscription.
 * - Subscribe to asset creation with assetCreate filter
 * - Subscribe to asset transfers with type and assetId filters
 * - Track opt-in and transfer transactions
 *
 * Prerequisites:
 * - LocalNet running (via `algokit localnet start`)
 */
import { algo, AlgorandClient } from '@algorandfoundation/algokit-utils';
import {
  printHeader,
  printStep,
  printInfo,
  printSuccess,
  printError,
  shortenAddress,
  createFilterTester,
} from './shared/utils.js';


async function main() {
  printHeader('04 — Asset Transfer Subscription');


  // Step 1: Connect to LocalNet
  printStep(1, 'Connect to LocalNet');
  const algorand = AlgorandClient.defaultLocalNet();
  const status = await algorand.client.algod.status();
  printInfo(`Current round: ${status.lastRound.toString()}`);
  printSuccess('Connected to LocalNet');


  // Step 2: Create 2 accounts (creator, receiver)
  printStep(2, 'Create and fund 2 accounts (creator, receiver)');
  const creator = await algorand.account.fromEnvironment('ASSET_CREATOR', algo(100));
  const receiver = await algorand.account.fromEnvironment('ASSET_RECEIVER', algo(100));
  const creatorAddr = creator.addr.toString();
  const receiverAddr = receiver.addr.toString();
  printInfo(`Creator: ${shortenAddress(creatorAddr)}`);
  printInfo(`Receiver: ${shortenAddress(receiverAddr)}`);
  printSuccess('2 accounts created and funded');


  // Step 3: Create an ASA (fungible token) from creator account
  printStep(3, 'Create ASA from creator account');
  const createResult = await algorand.send.assetCreate({
    sender: creator.addr,
    total: 1_000_000n,
    decimals: 0,
    assetName: 'TestToken',
    unitName: 'TT',
  });
  const assetId = createResult.assetId;
  const createRound = createResult.confirmation.confirmedRound!;
  printInfo(`Created asset ID: ${assetId.toString()}`);
  printInfo(`Confirmed round: ${createRound.toString()}`);
  printSuccess('ASA created');


  // Step 4: Receiver opts in to the asset
  printStep(4, 'Receiver opts in to asset');
  const optInResult = await algorand.send.assetOptIn({
    sender: receiver.addr,
    assetId,
  });
  printInfo(`Opt-in txn ID: ${optInResult.txIds.at(-1)}`);
  printSuccess('Receiver opted in');


  // Step 5: Creator transfers tokens to receiver
  printStep(5, 'Transfer 500 tokens from creator to receiver');
  const transferResult = await algorand.send.assetTransfer({
    sender: creator.addr,
    receiver: receiver.addr,
    assetId,
    amount: 500n,
  });
  printInfo(`Transfer txn ID: ${transferResult.txIds.at(-1)}`);
  printSuccess('Transferred 500 tokens');


  // Watermark: just before the asset creation round
  const watermarkBefore = createRound - 1n;


  const testFilter = createFilterTester(algorand.client.algod, watermarkBefore);


  // Step 6: Subscribe with assetCreate filter — matches the creation transaction
  printStep(6, 'Filter: assetCreate = true');
  const createTxns = await testFilter(
    'asset-create',
    { assetCreate: true },
    1,
    'assetCreate filter matched 1 creation transaction',
    txn => printInfo(`  Created asset: ${txn.createdAssetId} | txn: ${txn.id}`),
  );


  // Step 7: Subscribe with type=axfer + assetId filter — matches opt-in and transfer
  printStep(7, 'Filter: type = axfer, assetId = created asset');
  const axferTxns = await testFilter(
    'asset-transfers',
    { type: 'axfer', assetId: assetId },
    2,
    'axfer filter matched 2 transactions (opt-in + transfer)',
    txn => {
      const axfer = txn.assetTransferTransaction!;
      printInfo(
        `  Transfer: ${shortenAddress(txn.sender)} -> ${shortenAddress(axfer.receiver)} | amount: ${axfer.amount} | txn: ${txn.id}`,
      );
    },
  );


  // Step 8: Summary
  printStep(8, 'Summary');
  printInfo(`Asset ID: ${assetId.toString()}`);
  printInfo(`assetCreate filter: ${createTxns.length} matched (creation)`);
  printInfo(`axfer + assetId filter: ${axferTxns.length} matched (opt-in + transfer)`);


  printHeader('Example complete');
}


main().catch(err => {
  printError(err.message);
  process.exit(1);
});

Other examples

Section titled “Other examples”