Gas vouchers

Vouchers, issued by any actor empower users with gas-free interactions, enabling them to send messages to specific programs seamlessly.

Use api.voucher.issue method to issue a new voucher for a user to be used to pay for sending messages to program_id program.

  import { VoucherIssued } from '@gear-js/api';

  const programId = '0x..';
  const account = '0x...';
  const tx = api.voucher.issue(account, programId, 10000);
  tx.signAndSend(account, (events) => {
    const voucherIssuedEvent = events.events.filter(({event: {method}}) => method === 'VoucherIssued') as VoucherIssued;
    console.log(voucherIssuedEvent.toJSON());
  })

Use api.voucher.exists method to check that the voucher exists for a particular user and program:

const voucherExists = await api.voucher.exists(programId, accountId);

To send message with voucher set prepaid flag to true in the first argument of api.message.send and api.message.sendReply methods. Also it's good to specify account ID that is used to send the extrinsic to check whether the voucher exists or not.

let massage = await api.message.send({
  destination: destination,
  payload: somePayload,
  gasLimit: 10000000,
  value: 1000,
  prepaid: true,
  account: accountId,
}, meta);