System API

The System API provides a way to query the system information of the blockchain. It allows you to query the chain name, version, health, and more. This API is available through the SystemApi class from the polkadart package.

Sample usage

import 'package:polkadart/apis/apis.dart';
import 'package:polkadart/polkadart.dart' show Provider;

void main() async {
  final provider = Provider.fromUri(Uri.parse('wss://rpc.polkadot.io'));
  final systemApi = SystemApi(provider);
  final chain = await systemApi.chain();

  print(chain);
}

You will get the following output:

Polkadot

Methods

There are several methods available in the SystemApi class that allow you to query the system information of the blockchain. Here are some of the most commonly used methods:

name

Future<String> name()

Get the node’s implementation name. Plain old string.

version

Future<String> version()

Get the node implementation’s version. Should be a semver string.

chain

Future<String> chain()

Get the chain’s name. Given as a string identifier.

chainType

Future<ChainType> chainType()

Get the chain’s type.

health

Future<Health> health()

Return health status of the node.

Node is considered healthy if it is:

• connected to some peers (unless running in dev mode)
• not performing a major sync

localPeerId

Future<String> localPeerId()

Returns the base58-encoded PeerId of the node.

localListenAddresses

Future<List<String>> localListenAddresses()

Returns the multi-addresses that the local node is listening on

The addresses include a trailing /p2p/ with the local PeerId, and are thus suitable to be passed to addReservedPeer or as a bootnode address for example.

peers

Future<List<PeerInfo<H, N>>> peers() async {

Returns currently connected peers

unsafe: This method is only active with appropriate flags

accountNextIndex

Future<int> accountNextIndex(String account)

Returns the next valid index (aka nonce) for given account.

This method takes into consideration all pending transactions currently in the pool and if no transactions are found in the pool it fallbacks to query the index from the runtime (aka. state nonce).

dryRun

Future<Uint8List> dryRun(Uint8List extrinsic, {BlockHash? at})

Dry run an extrinsic at a given block. Return SCALE encoded ApplyExtrinsicResult.

nodeRoles

Future<List<String>> nodeRoles()

Returns the roles the node is running as.

properties

Future<Map<String, dynamic>> properties() async

Get a custom set of properties as a JSON object, defined in the chain spec.

addReservedPeer

Future<String?> addReservedPeer(String peer)

Adds a reserved peer. Returns the empty string or an error. The string parameter should encode a p2p multiaddr.

/ip4/198.51.100.19/tcp/30333/p2p/QmSk5HQbn6LhUwDiNMseVUjuRYhEtYj4aUZ6WfWoGURpdV is an example of a valid, passing multiaddr with PeerId attached.

unsafe: This method is only active with appropriate flags

removeReservedPeer

Future<String?> removeReservedPeer(String peerId)

Remove a reserved peer. Returns the empty string or an error. The string should encode only the PeerId e.g. QmSk5HQbn6LhUwDiNMseVUjuRYhEtYj4aUZ6WfWoGURpdV.

unsafe: This method is only active with appropriate flags

reservedPeers

Future<List<String>> reservedPeers()

Returns the list of reserved peers

addLogFilter

Future<dynamic> addLogFilter(String directives)

Adds the supplied directives to the current log filter unsafe: This method is only active with appropriate flags

resetLogFilter

Future<dynamic> resetLogFilter()

Resets the log filter to Substrate defaults unsafe: This method is only active with appropriate flags

syncState

Future<SyncState> syncState()

Returns the state of the syncing of the node: starting block, current best block, highest known block.