Jaco
ff3882f5f7
* Bump common (w/ rxjs 7) * Adjust * pre bump * Cleanup imports * Add missing switchMap * CHANGELOG * Remove duplicate imports * Bump common * Direct rxjs import
42 lines
1.3 KiB
TypeScript
42 lines
1.3 KiB
TypeScript
// Copyright 2017-2021 @polkadot/api-derive authors & contributors
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// SPDX-License-Identifier: Apache-2.0
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import type { Observable } from 'rxjs';
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import type { ApiInterfaceRx } from '@polkadot/api/types';
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import type { HeaderExtended } from '../type/types';
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import { combineLatest, map, of } from 'rxjs';
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import { createHeaderExtended } from '../type';
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import { memo } from '../util';
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/**
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* @name subscribeNewHeads
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* @returns A header with the current header (including extracted author)
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* @description An observable of the current block header and it's author
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* @example
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* <BR>
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*
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* ```javascript
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* api.derive.chain.subscribeNewHeads((header) => {
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* console.log(`block #${header.number} was authored by ${header.author}`);
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* });
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* ```
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*/
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export function subscribeNewHeads (instanceId: string, api: ApiInterfaceRx): () => Observable<HeaderExtended> {
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return memo(instanceId, (): Observable<HeaderExtended> =>
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combineLatest([
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api.rpc.chain.subscribeNewHeads(),
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api.query.session
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? api.query.session.validators()
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: of(undefined)
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]).pipe(
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map(([header, validators]): HeaderExtended => {
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header.createdAtHash = header.hash;
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return createHeaderExtended(header.registry, header, validators);
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})
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)
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);
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}
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