Jaco Greeff
ad9d21cae2
* Remove outdated blockNumber refs * ExtendedHeader * Update subscribeNewHeads.ts
77 lines
1.6 KiB
Markdown
77 lines
1.6 KiB
Markdown
# @polkadot/rpc-core
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This library provides a clean wrapper around all the methods exposed by a Polkadot network client.
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## Usage
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Installation -
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```
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yarn add @polkadot/rpc-core
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```
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Initialisation -
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```js
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import Rpc from '@polkadot/rpc-core';
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import WsProvider from '@polkadot/rpc-provider/ws';
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const provider = new WsProvider('http://127.0.0.1:9944');
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const rpc = new Rpc(provider);
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```
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Retrieving the block header object for a given block header hash (a 0x-prefixed hex string with length of 64) -
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```js
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rpc.chain
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.getHeader('0x1234567890')
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.subscribe(
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(header) => console.log(header),
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(error) => console.error('error:', error)
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);
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```
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Retrieving the best block number, parent hash, state root hash, extrinsics root hash, and digest (once-off) -
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```js
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rpc.chain
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.getHead()
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.pipe(
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switchMap((headerHash) => {
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return rpc.chain.getHeader(headerHash);
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})
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)
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.subscribe(
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(header) => {
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console.log(`best #${header.number.toString()}`);
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console.log(`parentHash: ${header.parentHash.toString()}`);
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console.log(`stateRoot: ${header.stateRoot.toString()}`);
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console.log(`extrinsicsRoot: ${header.extrinsicsRoot.toString()}`);
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console.log(`digest: ${header.digest.toString()}`);
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},
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(error) => {
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console.error('error:', error);
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}
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);
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```
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Retrieving best header via subscription -
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```js
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api.chain
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rpc
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.subscribeNewHeads()
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.subscribe(
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(header) => {
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console.log(`best #${header.number}`);
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},
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(error) => {
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console.error('error subscribing:', error);
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}
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);
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```
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## Classes
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[Classes](SUMMARY.md)
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