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Introduction

@parity/product-sdk-tx is the submission layer. It signs and broadcasts an extrinsic, follows it through its lifecycle to block inclusion or finality, and reports every status transition. It also covers the machinery around a submission: atomic batching, dry-run extraction, weight buffering, Asset Hub account mapping, retries, and readable error formatting.

It closes the loop that Signer and Chain Client open: the signer gives you a PolkadotSigner, the chain client gives you the typed API to build a transaction, and this package submits it and tells you what happened.

When to Use It

  • To sign, broadcast, and track a single extrinsic with per-status callbacks (submitAndWatch).
  • To submit several calls as one atomic batch through the Utility pallet (batchSubmitAndWatch).
  • For the surrounding steps: dry-run extraction and weight buffering, Asset Hub account mapping for pallet-revive, retries with backoff, and dev signers for tests.
  • Do not use it to build the transaction object or open connections; that is the typed API from the chain client. To submit a contract call, prefer the higher-level Contracts package, which wraps this one.

Core Concepts

  • submitAndWatch(tx, signer, options): Signs, broadcasts, and watches through signing, broadcasting, in-block, and finalized. It returns a Result, resolving expected failures on the error channel rather than throwing.
  • TxResult and TxStatus: TxResult carries the txHash, the block, and the emitted events. TxStatus drives the onStatus callback for progress UI.
  • One Result to check: result.ok means the transaction was included and its dispatch succeeded. A dispatch that fails on chain is reported on result.error as a TxDispatchError, not as a successful result — so you branch on result.ok, not on a flag inside the value.
  • Typed error hierarchy: TxError is the base, with TxTimeoutError, TxDispatchError (dispatch failed on chain), TxValidityError (rejected before inclusion), TxSigningRejectedError (the user declined), TxBatchError, and TxDryRunError.
  • batchSubmitAndWatch(calls, api, signer, options): Wraps calls in Utility.batch_all by default (or batch / force_batch) and submits them as one transaction. All calls must target the same chain as the passed API.

Submit and Track a Transaction

Build a transaction from the typed API, then submit it with a status callback:

import { submitAndWatch } from '@parity/product-sdk-tx';
import { Binary } from 'polkadot-api';

const tx = chain.assetHub.tx.System.remark({ remark: Binary.fromText('hello') });

const result = await submitAndWatch(tx, signer, {
  onStatus: (status) => console.log(status.type),
});

if (result.ok) {
  console.log(`Landed in block #${result.value.block.number}`);
} else {
  console.error(result.error.message); // TxError
}

Batch Calls Atomically

Group several calls into one atomic transaction with batchSubmitAndWatch. With batch_all, either every call succeeds or the whole batch rolls back:

import { batchSubmitAndWatch } from '@parity/product-sdk-tx';
import { Binary } from 'polkadot-api';

const calls = [1, 2, 3].map((i) =>
  chain.assetHub.tx.System.remark({ remark: Binary.fromText(`batch-${i}`) }),
);

const result = await batchSubmitAndWatch(calls, chain.assetHub, signer, {
  mode: 'batch_all',
});

Limitations

  • Expected failures (dispatch error, timeout, signing rejection, validity error) arrive on the Result error channel, not as thrown exceptions.
  • A dispatch that fails on chain comes back on result.error as TxDispatchError; a result.ok transaction has both landed in a block and dispatched successfully.
  • The default waitFor is 'best-block'; the default timeout is 300 seconds.
  • Every call in a batch must target the same chain as the passed API; an empty call list returns a TxBatchError.

Where to Go Next

  • Guide Sign and Submit Transactions

    The task-focused recipe: derive an account, sign, and submit end to end.

    Sign and Submit Transactions

  • Learn Signer

    Where the PolkadotSigner this package consumes comes from.

    Signer

  • External API Reference

    The complete tx surface: submitAndWatch, batchSubmitAndWatch, and the error hierarchy.

    Visit Site

Last update: September 2, 2026
| Created: September 2, 2026